ASFB 2007 Abstracts

A two-person snorkelling team was used to monitor recruitment of the endangered Macquarie perch (Macqauria australasica) from October 2006 to January 2007 in the Cotter River, Australian Capital Territory. Four pools were surveyed weekly (in a 600 m reach) to detect the onset of hatching. Once hatching had commenced, a set of 25 pools spanning 8 km were monitored fortnightly. Recruitment was detected in 23 of 25 of the pools snorkelled, including 13 of 14 pools upstream of a rock-ramp fishway that was constructed in 2001. Recruitment of M. australasica had not previously been recorded above the fishway. The relative efficacy of this technique was compared with that of a conventional passive juvenile sampling technique in the four indicator pools. In the process, strategy for rapidly surveying Macquaria australasica nursery grounds is presented and the expansion in range of an endangered species population is confirmed.

The validity of using radio-telemetry, specifically variation in radio-signal strength, to quantify changes in activity of radio-tagged aquatic fauna was investigated under controlled conditions. We monitored short-term activity of two aquatic species, rainbow trout (Oncorhynchus mykiss) and Murray River crayfish (Euastacus armatus), that differ markedly in their primary mode of movement. Records of variation in signal strength were compared with the frequency, duration and type of movements as confirmed by time synchronised video. Active and inactive periods for both species were accurately detected by radio-telemetry. However, determining specific types of movement (i.e. burst swimming, cruising etc) proved problematic. Our findings are used to discuss applications of this technique for monitoring activity of site attached species.

We used a range of methods including tag and recapture, fyke nets, electrofishing and radio-tracking to investigate mesoscale movement of small to medium sized native fish in the highly regulated Macintyre and less-regulated Condamine Rivers of the Murray-Darling Basin. We define Mesoscale movement as being beyond a reach (riffle- pool complex) and may extend from hundreds of metres to tens of kilometres. We recorded meso-scale longitudinal movement by Hypseleotris spp., Neosilurus hyrtlii, Nematalosa erebi, Melanotaenia fluviatilis and Leiopotherapon unicolor associated with season, natural flow and flow stage. Flow stage also influenced direction of movement with aggregations of various species occurring below barriers during local flow events. We observed significantly lower catches during irrigation releases suggesting that movement cues are missing from artificial flow events. The worst drought on record has hampered efforts to study lateral movement. However, we did observe selective movement by Ambassis agassizii and Leiopotherapon unicolor to a small lagoon off the Macintyre River in summer. Subsequent sampling in this location suggested that spawning and recruitment had occurred post-connection. We discuss our findings in relation to loss of connectivity between habitats on the floodplain and within the river for small to medium sized fishes.

The marine migratory routes of most diadromous fishes are poorly known, with the oceanic phase of their life histories often considered a black box in analyses of population dynamics. We report on the effective use of natural chemical tags in otoliths to identify origins of a North American anadromous clupeid (Alosa sapidissima). Chemical signatures were based on combined elemental and isotope ratios in otoliths and water samples taken from all 20 major spawning populations across approximately 2700 km of coastline and 19 degrees of latitude. Signatures were highly distinct, with an average classification accuracy of 93%. These signatures allowed us to estimate mixed-stock compositions of one-year-old marine migrants and provided stage-specific information about the distributions of immature fish. Mixed-stock compositions were dominated by only two to three rivers for all collections and there was a distinct lack of southern populations in the mixtures. Estimates of mixed-stock compositions for these immature fish differ significantly from those reported for older age classes. These patterns suggest this species may exhibit ontogenetic niche shifts in their migratory strategies after their transition to marine habitats.

In light of the pressures on water resources in Western Australia, there is an increasing demand for independent ecological impact assessments of future supply options. This study examined the fish migration patterns of fishes in the Blackwood River and its tributaries within and outside the surface expression zone of the Yarragadee Aquifer; an identified yet controversial water supply option for Perth. Fish migration patterns, population demographics and community structure were related to a number of key environmental variables. Main channel sites receiving most groundwater discharge had much greater abundances of salt intolerant freshwater native species than those upstream of the discharge. This suggests that groundwater input in summer provides refuge habitat and this enables those populations to continue to be sustainable in the main channel. Many of the spatial migration variations were also attributed to differences in hydrological regimes of these systems. For example, Freshwater Cobbler migration strength was positively correlated with main channel base flows. The perennial Milyeannup Brook provided crucial breeding habitat for the threatened Balston’s Pygmy Perch and the species is particularly vulnerable to predicted habitat decline due to aquifer extraction. Other impacts on these fauna by changes in environmental variables are discussed.

S. australasicus is a serial spawner with asynchronous oocyte development and indeterminate fecundity, and is a suitable application of the Daily Egg Production Method (DEPM). Mean spawning frequencies ranged from 2 to 11 days. Mean batch fecundity was 69,894 ±4,361 oocytes per batch. Morphological criteria were established for identifying eggs. Middle and late stage eggs can be identified with a high degree of confidence. However, significant uncertainty exists regarding the identification of early stage eggs. Only early stage eggs with a high probability of being S. australasicus were included in the analyses. A total of 4,025 eggs were collected from 2,386 plankton samples obtained during 12 research surveys. The main spawning season occurs during summer and early autumn off southern Australia and during late winter and early spring off eastern Australia. The location of spawning off southern Australia varies between years. The main spawning ground off eastern Australia is shelf waters of southern Qld and northern NSW. Most conservative estimates of spawning biomass in the areas surveyed off southern and eastern Australia were within the ranges of 45,000-70,000 t and 20,000-60,000 t. respectively. The DEPM is the stock assessment method that will underpin the Harvest strategy for the Commonwealth Small Pelagic Fishery.

The biomass of snapper in SA shows considerable inter-annual variation resulting from changes in 0+ recruitment. To understand inter-annual recruitment variation, temporal patterns of reproduction, aspects of early life history and the relationship of these to water temperature were studied in Spencer Gulf, the region that contributes 70% of South Australia’s snapper catch.

0+ snapper distribution and abundance were assessed by a trawl survey undertaken in April of each year since 2000. Reproductive samples of snapper were collected from northern Spencer Gulf during the spawning seasons of 2005/06 and 2006/07, and analysed macro- and microscopically. Aspects of the early life history of snapper were interpreted from otolith microstructure.

Inter-annual abundance of 0+ snapper was highly variable but distribution was consistent between years, with one small nursery contributing the majority of the catch. Spawning was continuous from November to early February but peaked in December. From otolith microstructure, birth dates showed that most successful recruits were spawned from mid-December to mid-January. Thus, whilst spawning occurred over a prolonged period, windows of opportunity for recruitment were limited. Periods of spawning when water temperature was between 22 and 24șC were particularly important and thus may be a key determinant of 0+ recruitment dynamics.

The mean total protein content showed a declination in late embryos resulting from spawning caused by induction using HCG hormone and LHRH hormone each separately, while it showed an increase in the late fertilized embryos resulting from mothers treated with a mixture of HCG + LHRH . On the contrary, the total mean of lipid content showed an opposite results. The total individual amino acid concentrations showed a declination in late embryos resulting from mothers treated with HCG hormone and LHRH hormone each separately showing a normal consumption pattern towards embryos development except Arginine, unlike embryos resulting from mothers treated with a mixture of HCG + LHRH as they showed an increase in the mean total amino acids indicating abnormal consumption pattern except Aspartic acid.

The individual essential and non-essential amino acid profile concentrations of early fertilized embryos showed highly significant differences as P≤0.01 except cystin and isoleucine which showed moderately significant differences as P ≤ 0.05. The essential amino acid Lysine showed the highest concentration level among all acids concerning early fertilized embryos resulting from mothers treated with LHRH hormone, while the non-essential amino acids Proline and Glutamic acid showed the highest concentration level amongst the three treatments in early fertilized embryos resulting from mothers treated using HCG hormone and LHRH hormone each separately.

The qualitative and quantitative determination of fatty acids in the investigated two stages of embryonic development revealed fluctuations among the stages and the hormonal treatment of mothers. Almost all treatments displayed high significant differences in the total concentrations of saturated and unsaturated fatty acids as P ≤0.01. Arachidonic acid is the major precursor, which is involved in the regulation of numerous physiological processes such as growth, development and eicosanoid production. This acid was found in a low concentration in early fertilized embryos resulting from mothers treated with HCG hormone then increased in late embryos of the same treatment indicating better growth of embryos, while in the embryos resulting from other two treatments of mothers it showed a declination in late embryos indicating high consumption and bad formation of membranes and eicosanoid production. The same pattern occurred concerning the concentration of Docosahexanoic acid in early fertilized embryos resulting from mothers treated with HCG hormone, while in late embryos resulting from other two treatments of mothers it showed a declination indicating unsuccessful development of embryos.

Fishery processes of selectivity and recruitment to legal size vary with fish length, and are mediated by fish growth. However most fishery models are age-based. To model length-dependent change within each cohort, fish numbers must vary dynamically with length as well as age in the model population array. The fishery model formalism described here achieves this by a partition of the continuous length-at-age distribution. This method is computationally efficient and cleanly differentiates legal from sub-legal fish. Fish numbers within each cohort are partitioned into length bins, called ‘slices’. A ‘slice’ is defined and calculated as the fish in each cohort length-at-age distribution that have grown into legal size since the start of the previous time step. When growth is estimated from catch length and age samples separate from the stock assessment, biases result from the implicit assumption that catch samples are representative of the population, and from ignoring length-dependent change within cohorts. These biases are avoided by integrating recruitment, growth and selectivity estimation into a stock assessment likelihood that represents changing population numbers by both age and length. Size-dependence also permits a natural extension of fishery models to trophic interactions with the surrounding ecosystem.

The Western King Prawn is a short-lived, highly valued crustacean that exists at its latitudinal limit in South Australia’s unique gulf systems. Unlike most other prawn trawl fisheries, the Spencer Gulf Prawn Fishery (SGPF) has had a remarkably stable history of catches, most likely the result of appropriately conservative management strategies, suitable environmental conditions for spawning and recruitment and highly productive juvenile habitats. Regardless of this stable history, threats to sustainability include anthropogenic effects such as the impacts of industry, introduction of disease and the potential for over-fishing and environment effects such as climate change. Historically, fishery-independent surveys were conducted in juvenile habitats in the intertidal zone. Also, fishery independent surveys conducted on the fishing grounds provide data on the number of new recruits entering the fishery and data on the catches of prawns just below harvest size. Reliable indices of future harvest are not only essential for determining fishery sustainability, they also increase income certainty to the industries that harvest them. In this study we aim to compare the effectiveness of three indices of future harvest: abundance of juvenile prawns in intertidal habitats, abundance of newly recruited prawns to the fishery and abundance of prawns just below harvest size.

Goldfish (Carassius auratus) currently have no legal status in New Zealand, but new evidence suggests that in the wild they should be recognised a pest fish species. Feral goldfish are widespread in New Zealand, and boat electrofishing has revealed that they are abundant throughout the lower Waikato basin. Juveniles can be found at most times of the year, suggesting that they do not have the same temperature limitations on breeding as koi carp (Cyprinus carpio). Because of their size, koi carp dominate the fish biomass at most Waikato locations, but goldfish generally outnumber koi carp. Goldfish breed freely, and they hybridise with koi carp. About 1% of our koi carp catch in the Waikato is hybrids, though we have no evidence that such hybrids are fertile. Environment Waikato, a regional pest management authority responsible for the Waikato region, has recognised feral goldfish as a pest in its Draft Regional Pest Management Strategy, and is the first regional council in New Zealand to do so.

The Carp Management Program (CMP) of the Inland Fisheries Service (IFS) has been using intense, physical removal techniques in lakes Crescent and Sorell since European carp (Cyprinus carpio) were identified as inhabiting Tasmania in 1995. In 1997, the implementation of transmitters and radio tracking equipment was incorporated into the program. Subsequently, with the help of grid reference charts, the CMP have recorded all tracking events and location data for each individual fish hosting a transmitter. Tracking information is stored within a Microsoft Access database. To visualise historical tracking data in a spatial sense, a datalink has been constructed to upload specific tracking information with the output displayed in Microsoft Mapinfo. The datalink enables the user to view individual tracker fish behaviour for any given time period within either water body. Thematic distribution maps can also be displayed for specific intervals of time, illustrating favourable areas of inhabitancy. By incorporating water temperature and lake level data into the database, the areas where tracker fish are likely to be at particular environmental conditions can be determined. Ultimately, the carp database is a useful management tool in contributing to the fishdown and eventual eradication of the European carp from Tasmania.

Abundance estimation is the cornerstone of fisheries management. Mark-recapture techniques based on the Petersen model remains the most often used approach. Few studies compare population estimates against known numbers. The fishing down to eradication of carp in two closed lakes in Tasmania provides absolute population numbers with which to compare the results of several population estimate studies carried out over the past 8 years. A major mark-recapture exercise in Lake Crescent during the summer of 1998-99 resulted in a Petersen estimate of 2053 carp and a Schnabel estimate of 1910 carp remaining. From 2000 to 2002 male carp were tagged and released back into Lake Crescent. A modified Petersen estimator was developed to utilise the mark-recapture information provided by continuing fishing effort during this time. A final conclusive population estimate was instigated in March 2003 with the mass release of 160 tagged adult males. The results of these estimates have proven remarkably accurate considering the large size (23 sq km) of the lake. CPUE based population estimates extrapolated from the Lake Crescent study onto the neighbouring Lake Sorell have precluded the need for releasing any marked fish into this much larger lake.

Since its inception within the Inland Fisheries Service in 1995, the Carp Management Program has been successful in its objective to contain European carp in Lakes Sorell and Crescent. The data, knowledge, skills and infrastructure that have been built over this period have enabled the program to demonstrate near complete carp eradication in Lake Crescent. Estimates indicate the carp population in Lake Crescent has been reduced to less than 10 fish. Physical removal of the last remaining carp in Lake Crescent has been challenging owing to reduced catch per unit effort, which is not surprising given the dwindled population size. Contrary to the situation in Lake Crescent, the size of the lake, wetland spread and response to rainfall the eradication of carp from Lake Sorell has been even more difficult. To address both these situations the program has integrated additional approaches to assist effective removal of carp from both the lakes while preventing any recruitment.

Over 11 years the Inland Fisheries Service Tasmania has made concerted effort towards controlling and eradicating common carp, Cyprinus carpio, from Lakes Crescent and Sorell. Remarkably, carp have been contained with estimated carp numbers reduced to <10 and <100 in lakes Crescent and Sorell respectively. However removal of last few carp has been a challenge necessitating additional integrated management strategies. During the summers of 2005-2006 and 2006-2007, field trials were conducted using reproductively primed odour donor female fish to attract and trap wild free- ranging carp of both sexes. This was based on premise that fish including cyprinids produce reproductive pheromones that can attract and recognise conspecifics. The ability of the odour donor female carp to attract conspecifics was measured by recording the movement of radio-tagged male carp as well as the number of fish recovered from traps located at vantage points. Trials conducted in 2005-2006 were particularly successful in attracting and trapping from as far as 4 km away. This work demonstrates the feasibility of deploying odour donor carp to assist in trapping and removing wild free-ranging carp under field conditions. However the molecules (pheromones), mechanisms of chemoreception and the influence/interaction of environmental factors remain poorly understood.

Northern Australia hosts two-thirds of the Australian freshwater fish fauna and most of the unexplored diversity. Despite relatively low levels of development, there are significant pressures and a desire to avoid repeating management mistakes of more developed catchments. Exotic and translocated native fishes pose a significant threat to this biodiversity, even in relatively unimpacted catchments. Two new projects are exploring this native diversity and the increasing threat of pest fish invasions. The first is “A Comprehensive Analysis of Freshwater Fish Faunas of Northern Australia and Their Key Management Needs”. This project aims to database the recorded distribution of all freshwater fishes across northern Australia; to identify and fill gaps in field survey effort; undertake a genetic and taxonomic revision of terapontid grunters; and to produce a website portal for this information. The second is “Integrated Management of Tilapia and Other Exotic and Native Pest Fishes in NE Queensland”. This region hosts 19 exotic and 36 translocated native fish species, with the rate of new range incursions, especially for exotic species, increasing rapidly. This project covers public education; field survey to delineate pest fish distribution; research into impacts of tilapia; and developing control actions to limit tilapia establishment and dominance.

Introduced to Australia in the late nineteenth century, common carp have become a major freshwater pest. Thriving in disturbed habitats, they degrade waterways and compete with native fish for resources. Their mobile nature and fecundity, along with illegal human-assisted dispersal, has allowed them to colonise nearly all of the Murray-Darling river system, as well as many coastal rivers. Their broad tolerance to salinity and temperature gives them the potential to occupy possibly all permanent freshwater habitats in Australia.

This project explores the population genetics of common carp with the aim of making recommendations for control programs. Preliminary results have so far found evidence that at least two genetic strains have made a significant contribution to the carp population of the Murray-Darling Basin (MDB); there are clear patterns of colonisation, with some populations being established in discrete colonisation events; although there are high levels of geneflow between most regions, the movement of carp is limited by dams and restricted water flows; carp may be spawning predominantly in three ‘hot-spots’; and there are approximately 9-10 potential management units within the MDB. This information, when combined with demographic and modelling data, will be useful in devising control programs for this pest species.

The introduction and spread of exotic species in various parts of the world is regarded by many as a major threat to global biodiversity, and freshwater fish are both significant vectors of, and vulnerable to, this threat. Many ornamental fish are brought into Australia for the aquarium trade, and between 12 and 14% of Australians are thought to keep aquaria. Thirty species of liberated aquarium fish are known to have established self-sustaining populations in Australia. The genetic threats of these exotic species are likely to be: 1) hybridisation and introgression; 2) problems associated with small populations owing to deleterious ecological interactions and disease; and 3) hybridisation among exotic taxa. Hybridisation, introgression and the breakdown of species boundaries pose a significant risk to biodiversity throughout the world. The old paradigms of biological species being reproductively isolated do not hold under empirical analysis. Particular groups, such as fish and plants, readily hybridise, and hybridisation and introgression indeed appear to be an intrinsic part of the evolutionary process. This presentation will discuss these threats and review existing data on the current situation in Australia.

Many of New Zealand’s endemic non migratory freshwater fish species are currently threatened as a result of competitive exclusion and/or direct predation by salmonids. Tools to eradicate and manage exotic fish species in running waters in New Zealand are presently limited. Interestingly, salmonids exhibit high sensitivity to low pH water relative to many native New Zealand species. This vulnerable aspect of their physiology was used to explore the possibility of using low pH to 'repel' trout in static and flowing waters. Laboratory experiments were conducted to test the response of trout to three pH levels; pH 7.0 (neutral control), pH 5.5 and pH 3.5. Four replicate trials of each were conducted with 'naive' brown trout (80-150mm) being used for each trial. Responses of trout to the same pH levels were investigated in static and flowing choice chamber units. Responses of trout pre and post treatment were analysed by viewing taped video recordings of fish movement between chambers during the pre and post observation periods. Trials indicate significant potential for further development of this tool with a very strong avoidance response by trout to both the mildly acidic (5.5) and strongly acidic (3.5) levels relative to control trials. No mortality of trout was seen and the use of acidification may be preferred by other stakeholders if trout can be removed without killing. The small quantity of acid required per volume of water to attain a desired avoidance response means that the logistics of using this tool in small streams without major adverse effects is a real possibility.

The growth rate of larval fish is a predictor of the annual supply of young fish, but fisheries science has not exploited this remarkable finding, particularly for Australia’s sparse and diverse fisheries. Using a rare 28 year archive of herring otoliths from the Bay of Fundy off eastern Canada, with robust year class strengths based on virtual population analysis, we tested the hypothesis that strong year classes were produced from larger otoliths, and weak year classes were produced from smaller otoliths. Two weak year-classes were selected with ~5*10^8 individuals at 1 year old, and two strong year-classes were selected with abundances ten-fold greater. We examined otolith size (diameter and area) of 2, 3, 4, and 5 year-old fish at approximately 18 months of age, and measured the otolith radius of 3 year-old fish at 6 months, 2 months and 1 month post-hatch. In 2 year-old fish, the area of the otolith at ~18 months old was correlated with year class strength, but effects were quickly removed as the cohort moved onto 3, 4, and 5 years old. Measures of daily increment growth in 3 year-old fish did not yield significant differences among year-classes due to high variability of larval growth rates in certain year-classes.

The East Australian Current (EAC) and the Tasman Front dominates the oceanography off the east coast of New South Wales (NSW), Australia. This study aimed to identify the larval fish assemblages transported within the EAC and which taxa were entrained into the Tasman Front region and therefore advected away from the coast. These two locations are likely areas of enhanced biological productivity that may influence the larval fish communities. The study surveyed larval fish communities in these regions and compared EAC versus coastal sites (northern NSW) and EAC versus Tasman Sea sites (Tasman Front region). The northern NSW zone contained 93 taxa with the most common being Sardinops sagax (21.1%), carangids (18.7%), Scomber australasicus (14.8%) and myctophids (5.8%). The communities of the EAC, dominated by myctophids, carangids and S. australasicus differed from the coastal sites dominated by S. sagax. Unlike the northern NSW zone, the two communities in the Tasman Front zone were differentiated more by abundance rather than composition. Sixty two families occurred in the Tasman Front zone, with S. australasicus (27.2%), S. sagax (19.9%), bothids (14.4%) and myctophids (9.0%) dominating. More taxa and greater abundance occurred closer to the coast and more taxa and greater abundance was found in the EAC than the Tasman Sea. Coastal and shelf species (S. sagax, S. australasicus, Engraulis australis, bothids, serranids and carangids) drove the trend of greater abundance closer to the coast. Myctophids were the only family to show a relatively uniform distribution with distance from the coast and between the two water bodies (EAC and Tasman Sea). Higher numbers of taxa and abundance in the EAC compared with the Tasman Sea was not expected as the EAC is relatively oligotrophic. This trend, however, diminished with distance from the coast and may only be associated with the initial stages of the Tasman Front. The presence of coastal species from the northern NSW zone at EAC sites in the Tasman Front zone suggests coastal assemblages are being entrained into the EAC as it begins its meander towards New Zealand.

Migratory galaxiids and bully species are characterised by dramatic ontogenetic niche separation between a pelagic larval and benthic adult phase. Adult growth and reproduction occurs in freshwater, whereas larvae are expected to develop at sea. Traditionally, a marine pelagic larval period was thought beneficial because it resulted in offspring dispersal. An alternative view argues a pelagic larval period evolved because small larvae need a pelagic environment for rearing, not because dispersing larvae were adaptive. If so, streams upstream of lakes will be dominated by recruits derived from that lake, irrespective of any connections to the sea. We determined the proportion of fish exhibiting diadromous or non-diadromous recruitment in 6 paired catchments with and without coastal lakes. High retention rates were common within lakes. Most strikingly, 20 out of 20 Galaxias brevipinnis collected upstream of Lake Moeraki, the outlet of which is only 3km from the coast, were self-recruiting. Given the predominance of self-recruitment upstream of coastal lake systems, we suggest retention in estuaries and harbours may also be common. Management of whitebait metapopulations, and other species with pelagic larvae, needs to incorporate an understanding of larval ecology and appreciate the potential for localised recruitment dynamics in systems that promote retention.

Quatrafoil light traps are routinely used in the study of larval fish. They are inexpensive, easy to deploy, and are generally an effective means of capturing fish larvae in a wide range of aquatic environments. This study demonstrates that juvenile and adult small-bodied fish frequently encountered as by-catch in light traps can significantly reduce the abundance and diversity of fish larvae sampled via confined predation within the trap prior to clearing. To counter this problem we experimentally examined the effect of fitting a fine mesh to the outside of light traps to exclude adult small-bodied fish thus effectively reduce the predation effect within the trap. The experiment was carried out in the field during January 2007 in the Lindsay River, an anabranch of the lower River Murray in north-west Victoria. Results showed that traps fitted with mesh effectively excluded adult small bodied fish to result in a significant increase in the number of larvae sampled as compared to standard light traps. These results support the use of mesh on light traps to reduce confined predation and enhance sampling efficiency.

Young (11-15 days, 8-10 mm), larvae of Amblyglyphidodon curacao were identified by mitochondrial DNA. Their behaviour dispersal-relevant was studied in lab and sea at Lizard Island, Great Barrier Reef. Behaviour varied little with size. Critical speed was 27.5 ± 1.0 cm s^-1, and in situ speed was 13.6 ± 0.6 cm s^-1, and equalled mean current speed. Unfed larvae swam 52.0 ± 8.6 km at 8-10 cm s^-1, losing 25% wet weight. Modal depth was 7.5 m and 11.25 m at leeward and windward sites, respectively. Over 80% of 71 larvae observed swam directionally. Larvae avoided NW bearings, with an overall mean SE swimming direction. Larvae made smaller turns when swimming SE than in other directions, making it likely they would continue to swim SE. When swimming NW, 62% of turns were left, resulting in rapid change away from NW. Clearly, the larvae knew the direction in which they were swimming, and chose SE. The cues used for orientation are unclear. Near Lizard Island, A. curacao larvae swam into the mean current at speeds equivalent to it, could do this for many hours, and chose different depths in different locations. These behaviours will strongly influence dispersal and are similar to behaviour of other settlement-stage pomacentrids that are older and larger.

Larval habitats of six small pelagic fishes, namely Etrumeus teres, Sardinops sagax, Engraulis australis, Emmelichthys nitidus, Trachurus spp. and Scomber australasicus, are described and compared along the south-eastern Australian shelf based on links with discrete water masses and other oceanographic features in the region. Data comes from five intensive ichthyoplankton surveys conducted between southern Queensland and north-eastern Tasmania (~1050 nm) in 2002-2004. Three major water masses were identified in the region during surveys, i.e. East Australian Current (EAC), Tasman Sea (TAS), and a composite mixed water mass (MIX). Taxa distributions were strongly linked to these water masses, shifting southwards following the strengthening of the EAC. Larvae of E. teres, S. sagax, E. australis, and S. australasicus were strongly associated with EAC and MIX water, with greatest abundances typically occurring near the EAC-MIX interface or in upwelling areas where the EAC separates from the coast. Larval Trachurus spp., comprising two closely-related species (T. novaezalandiae and T. declivis), were highly abundant across all water masses, although preliminary analyses of postflexion stages suggest differing preferences. Larvae of E. nitidus were restricted to cooler TAS water. Results highlight the close affinity between larval distributions and discrete water masses, implying that these may be used as a proxy to identify potential spawning areas.

Flow disturbance around headlands and islands has the potential to create patchiness in pre-settlement fish, and thereby influence patchiness in settlement. Surface larval fish assemblages within and outside the wake of North Solitary Island off northern New South Wales (29° 55′ S, 153° 23′ E) were investigated during September 2004 to determine the effect of flow disturbance on the short term abundance and composition of continental shelf larval fish communities. A distinctive wake was apparent in the flow-field of the poleward East Australian Current (~0.5 ms^-1), evident from the vessel’s Acoustic Doppler Current Profiler. Three replicate 10 km long transects, each comprising 24 surface plankton tows (average volume filtered; 150 m^-3), were made across the island wake using a 500 ”m mesh net. Change in temperature between the surface and 40 m depth at each sample location indicated a lateral mixing of coastal and oceanic water masses within the wake. Possible vertical mixing was indicated by an increase in abundance ratios calculated between abundant coastal and oceanic taxa within the wake. Abundances of clupeid, carangid, pomacentrid, scomberesocid, scombrid, gobiid, triglid, and platycephalid larvae were greater, either within the wake, or near wake fronts, however trends varied among transects. Our results suggest island wakes may be associated with local peaks in larval abundance of numerous taxa and could potentially increase the spatial complexity of larval fish assemblages through induced mixing of different water masses.

The South Australian calamary resource is shared by three sectors. Juveniles and sub-adults are incidentally caught by commercial prawn trawlers, while adults are targeted by commercial Marine Scalefish licence holders and recreational fishers on inshore spawning grounds. The trawlers are permitted to retain and sell calamary as ‘by-product’, however, historically, there has been no legislative requirement for this catch to be reported. As such the assessment of South Australia’s calamary fishery is currently limited to the analysis of commercial catch and effort data collected from the Marine Scalefish Fishery.

In December 2005 the South Australian prawn fisheries implemented mandatory reporting of all retained by-product. This was in response to recommendations made by the Commonwealth Department of Environment and Heritage to assess and monitor all by-catch species in compliance with the Environment Protection and Biodiversity Conservation (EPBC) Act. This reporting method, however, is under-representative of total calamary catch as fishers generally discard small animals and those in poor condition. Through structured fishery-independent surveys this study obtained spatial and temporal estimates of calamary by-catch within the prawn fishery, compares estimates with reported catches and discusses the feasibility of using on-going by-catch monitoring as a potential performance indicator in the Marine Scalefish Fishery.

A scientific observer-based survey was used to quantify the retained and discarded catches in the largest trap fishery for the Portunid crab, Portunus pelagicus, in south-eastern Australia (i.e. Wallis Lake) during the 2002/03 fishing season. Overall 81% of male and 79% of female P. pelagicus captured were larger than the current minimum legal carapace length (i.e. 60 mm) and therefore retained. It was estimated that approximately 385,988 (± 37,551) P. pelagicus were retained and 183,653 (± 29,716) discarded from the trap fishery during the 2002/03 season. The quantities of non-target species captured were generally very low, and significantly less than that generally reported for other crab-trap fisheries. Acanthopagrus australis was the most abundant bycatch species, with an estimated total of 2,445 (± 1,564) caught, representing 43% of the total bycatch, during the 2002/03 season. Discarded organisms were in good condition when returned to the wild. This study demonstrates that the Wallis Lake trap fishery for P. pelagicus is relatively selective and has minimal direct impact on non-target species.

In South Australia, fishery independent surveys in the blue crab fishery have been conducted on an annual basis in Gulf St Vincent (GSV) and Spencer Gulf (SG) since 2002. The primary aims of the survey are to collect data on the abundance and size composition of blue swimmer crabs (Portunus pelagicus) to assist ongoing assessment of the blue crab stocks. Information has also been collected on incidental captures to support mitigation strategies for reducing by-catch. This survey investigates the relative catch composition from both commercial pots (90mm mesh) and research pots (55mm mesh). A total of 52 by-catch species (29 fish, 9 crustaceans, 10 molluscs, 3 echinoderms and 1 tunicate) were collected during the surveys, none of which are listed under the Environment Protection and Biodiversity Conservation Act 1999 as rare, threatened or endangered. Multivariate analysis confirms that research pots capture higher numbers of by-catch species and individuals than commercial pots. These analyses also reveal large differences in by-catch composition between the two gulfs. An industry sampling program is being implemented to address seasonal variability on by-catch composition and abundance.

Interactions between seals and trawl fishing gear often result in by-catch and incidental mortality. While by-catch rates are relatively well known, factors that contribute to these interactions, including seal behaviour whilst in the net, are poorly understood. In this study, mid-water trawl operations in the Commonwealth Small Pelagic Fishery were monitored using an underwater camera system. Video footage was available for almost 100 trawl shots.

Seals were observed inside the trawl net in 55% of tows, the interaction rate varying seasonally and peaking at over 70% between March and August. Seals entered the net through all phases of the trawl operation, with a significantly higher incident rate experienced whilst shooting the gear. There was a strong diurnal pattern in the occurrence of seals in the net that largely mirrored the distribution of fishing effort over the 24-h period. Seals entered and exited the net via the net mouth as well as the seal exclusion device escape hole. Not all seals escaped and mortalities were observed. By enlarging the escape hole it was possible to significantly reduce the mortality rate. In some cases interaction times substantially exceeded the maximum documented dive duration for fur seals, implying that not all seals that escaped would have survived.

The management of fishing must be undertaken within the context of the ecosystem(s) that support the exploited stocks, a management approach termed Ecosystem-Based Fisheries Management (EBFM). The WA Department of Fisheries (DoF) recognizes the inherent complexity in attempting to implement an EBFM system, including the need to consider a much wider range of processes, issues and data than is required for singe-stock management. Research on the implementation of EBFM is being undertaken in a project funded by the WA Marine Science Institution (WAMSI). This project aims to (1) develop mechanisms and processes for integrating EBFM into “mainstream” fisheries management, including the WA Government’s Integrated Fisheries Management (IFM) initiative, and (2) to source, identify and integrate appropriate supporting research. It is expected that EBFM will eventually subsume both traditional fisheries management and IFM. Ultimately, this project will provide stakeholders, including the broader WA community, with a much improved understanding of what EBFM means and how it could be achieved, which will engender within the WA community a greater understanding of sustainable management of marine ecosystems. This presentation provides an overview of how DoF and partners are progressing the implementation of EBFM.

Current markets for southern rock lobster (Jasus edwardsii) demand small (~1kg), “red” coloured individuals that are primarily located within inshore (<60m depth) grounds. As a result, fishing effort in recent seasons has shifted inshore, while offshore waters containing “speckled” low-value lobsters remain largely unfished. In South Australia, the feasibility of translocating offshore lobsters to inshore sites to promote colour change, and therefore market value, is currently being examined. In January 2007, a total of 2000 lobsters were translocated to an inshore reef at Ringwood, South Australia. To investigate potential ecological impacts of translocation on the inshore reef invertebrate community, dive surveys were conducted before and after translocation at both experimental and control sites. Surveys targeted the abundance of large (>50mm) motile invertebrates as estimated on three permanent 50m transects. Preliminary analysis found no initial difference in invertebrate community structure between control and experimental sites, which were dominated by sea urchins Heliocidaris erythrogramma, rock lobsters J. edwardsii, and feather stars (genus Cenolia). Resurveys, undertaken seven weeks after translocation, indicated that while lobster numbers increased significantly at experimental sites as expected, no interaction between treatment and time was detected between control and experimental sites. Future surveys are planned for 2007/08 to monitor potential long-term changes.

Dryland rivers drain one-third of the worlds land mass, yet they are not studied with the same intensity as rivers located in wetter climates, such as tropical rivers. For much of the time, dryland rivers exist as a series of disconnected, waterholes that represent the only refugia available to obligate aquatic biota such as fish. Highly variable rainfall can intermittently connect these waterholes both longitudinally along river channels and laterally across floodplains. This episodic flow is an important factor in the maintenance of aquatic food webs and ultimately populations of fish.

In 2006, we investigated how the availability of food resources is linked to the natural variation in primary productivity in the Moonie River SW Queensland, a dryland river in the upper reaches of the Murray-Darling Basin. The diets of the native bony bream (Nematalosa erebi) and yellow belly (Macquaria ambigua) were examined in the months following a moderate summer flood peak as the quality of food resources diminished.

Both fish species displayed variable diets within sampling periods reflecting generalised feeding strategies typical of fish in dryland river systems. Diets also varied between sampling periods indicating the ability of both species to persist during both high and low levels of resource quality.

This interaction between the native biota and food resource conditions highlights the need to consider how future water resource development plans will affect the natural hydrology of dryland rivers, and ultimately their fish assemblages.

The feeding ecology of three co-occurring labrids (Ophthalmolepis lineolatus, Notolabrus gymnogenis and Pictilabrus laticlavius), which are conspicuous on rocky reefs in temperate south-eastern Australia, were investigated. SCUBA observations showed that the feeding intensity, and hence the associated effects of these fishes on rocky reef invertebrate prey, was temporally consistent. Differences in the relative contributions of ingested prey and relative use of different feeding microhabitats revealed that the feeding ecology differed significantly among all three species. O. lineolatus fed on higher volumes of polychaetes, polyplacophorans, marginellid gastropods, bivalves and echinoids, which were sighted opportunistically in a wide selection of microhabitats, but particularly in sand/rubble. Ambush hunting was used regularly by smaller N. gymnogenis and all sizes of P. laticlavius to forage on amphipods, small decapods and small gastropods at algal bases or fronds and Diopatra dentata tubes. Amphipods were similarly important in the diet of smaller O. lineolatus. Larger N. gymnogenis foraged opportunistically in various microhabitats from which relatively higher volumes of decapods were obtained. The significant intra- and inter-specific differences in dietary compositions, allied with differences in the use of feeding microhabitats, would facilitate co-occurrence of these species and contribute to maintaining high richness of labrid species in reef systems.

Dietary studies are critical to an understanding of elasmobranch ecology and the role they play in marine ecosystems. The stomach contents of 136 male and 100 female Heterodontus portusjacksoni were obtained from July 2004 to March 2005 near Newcastle, New South Wales. The diet was broad (41 prey taxa) and displayed clear ontogenetic differences, but no differences between the sexes. Juveniles consumed mostly benthic infauna and epifauna (eg. Echiuroidea), whilst subadults occupied a transitional position to the adult diet, which was dominated by demersal pelagic prey (eg. squid). An ontogenetic shift in trophic level from secondary consumers (juveniles- subadults) to tertiary consumers (adults) in combination with the change in dietary composition, indicates a maturity-related shift in the ecological role of this species. Although some dietary overlap occurred, the ontogenetic variation in diet clearly demonstrated intraspecific resource partitioning was operating during the time that the three maturity stages cohabited.

Stable isotope data are used to track diets and movements of fish. Reliable interpretation depends on understanding fractionation between diets and tissues of consumer fish. We experimentally investigated the influence of diet on fractionation of carbon and nitrogen isotopes in mummichog, Fundulus heteroclitus, a common estuarine species in the eastern US. Fish muscle was analyzed both with and without lipids depleted in order to examine variability in isotopes that may be associated with muscle lipid content. Fish that had their diets swapped from artemia to either squid, clam or one of two artificial diets had uniquely different muscle isotopic composition than fish reared with a constant artemia diet. For all treatments, fish muscle was enriched in carbon and nitrogen isotopes compared to their diets. Lipid-depleted muscle was on average 1 per mil enriched compared to non-depleted muscle, and within and between treatment variability was not greatly altered. Our results show that assumptions of constant isotopic enrichment with respect to dietary sources will not always apply to ecological studies.

Time required for adult Australian smelt Retropinna semoni, to digest a meal of Daphnia carinata (10 prey items) was found to depend on temperature and feeding frequency based on sacrificial experiments in aquaria. At 10^oC, 20^oC and 30^oC, complete digestion occurred by 5 hr, 1 hr and 2 hr, respectively. This highlights an important functional difference among dietary samples collected in the field at different times of year and is likely applicable to many temperate fishes as poikilotherms. Also, an initial meal of ten D. carinata was digested more slowly (2 hr v 1 hr) if after its ingestion, Australian smelt continued to feed on copepods, as opposed to if additional feeding was prevented, at 20^oC. Collectively, these results provide an empirical basis for estimating zooplankton consumption by Australian smelt.

Murray hardyhead are a threatened native fish species currently limited to four Victorian and four South Australian populations. The reproductive cycle and diet of two isolated populations of Murray hardyhead from Lake Hawthorn and Cardross Basin 1 near Mildura Victoria were examined in this study. Both wetlands are managed for irrigation disposal and are experiencing declining water levels and increasing salinities as a result of improved drainage practices. Analysis of temporal variation in mean gonado-somatic index (GSI) indicated the species has a prolonged spawning season from September to January in both wetlands, with a spawning peak in October/November. Examination of ovaries and mean GSI throughout the breeding season indicated multiple batch-spawning within the breeding season. The diet in both populations consisted mostly of zooplankton with larger fish also feeding on larger prey including dipteran larvae and pupae, ostracods and fish eggs. A greater variety and abundance of food sources was recorded in the gut contents of fish from Cardross Basin 1 than Lake Hawthorn. Seasonal shifts in length frequency distribution and examination of annual increments on otoliths indicate Murray hardyhead appear to be a largely annual species, with the populations examined dominated by 0+ individuals.

A mark-recapture survey has been undertaken continuously between Yarrawonga and Tocumwal on the Murray River for the past 8 years. Anglers have been encouraged to return information on their captures and report on the fate of the individually tagged fish. Tagged fish removed by anglers from the tagged population can be incorporated into the analysis of the mark-recapture dataset using a recently developed analysis for jointly analysing live and dead encounters in a multi-state design. Due to analytic constraints, the data were divided into 150mm size classes, and the analysis of this construct yields fishing rates for the size classes (mm) 450-600 (13.5%); 600-750 (32.2%); 750-900 (35.3%); and 900+ (3%). We examine the implications of these fishing rates on the conservation management of Murray cod by including them in a stochastic population model for Murray cod.

The fish family Syngnathidae (seahorses, pipefish, pipehorses and seadragons) became fully protected in NSW in 2004. Syngnathids are threatened by unsustainable collecting, capture as incidental bycatch and habitat degradation. Although marine protected areas (MPAs) are an effective conservation strategy for many fishes, their value for syngnathids is untested. This project is assessing the benefits of an MPA (Fly Point-Halifax sanctuary zone, Port Stephens-Great Lakes Marine Park) for syngnathid conservation by comparing populations of White’s seahorse Hippocampus whitei, tiger pipefish Filicampus tigris and other syngnathids within and outside the sanctuary zone. Four study sites (two inside the sanctuary zone, two outside) have been monitored for 18 months. Syngnathids have been individually marked using visible implant elastomer tags. Population data on syngnathids have been collected using underwater visual census techniques and a comparison of different census techniques will be presented. Results will also be presented on the abundance of syngnathids in protected and non-protected sites, the relationship to predator abundance, and the habitat and depth usage of male and female seahorses.

Marine conservation planning to achieve representativeness requires information on scales and sources of significant spatial variation in assemblages. Variation in reef fish assemblage structure was investigated using a nested sampling design consisting of 2 areas (separated by 10s km), 2 locations (separated by km) and 3 sites (separated by 100s m). Baited remote underwater video stations (BRUVS) were used to sample reef fish on 2 occasions (6 months apart) prior to the enforcement of the Port Stephens-Great Lakes Marine Park. Significant variation in fish assemblages was apparent at all spatial scales and these differences were consistent between times. The effect of depth was tested by comparing reef fish assemblages between 16-30 m and 40-51 m, revealing significantly different assemblage structure between depths and replicate locations within each depth (separated by kms), but not between sites. Therefore to achieve representativeness the results suggest a need to protect multiple samples of reefs covering a range of depths. BRUVS proved to be useful for sampling depths greater than typically sampled by underwater visual census and provided relative abundance estimates of a wide range of species including commercially and recreationally targeted reef fish that are expected to show the greatest response to marine park zoning.

Pelagic fish are not generally thought to benefit from marine protected areas (MPAs) because they are highly migratory; their large home range is well beyond the usual scale of MPA boundaries. However, fishing effort for pelagic fish is often highly concentrated within the coastal zone, indicating that pelagic fish habitat in coastal regions may be predictable, and that pelagic stocks may benefit from MPAs sited in these areas. We use a novel mid-water baited video technique and otolith microchemistry to investigate the use of a coastal Australian MPA by yellowtail scad (Trachurus novaezelandiae) – the most common, and most commonly fished, small pelagic in Australian waters. Mid-water baited video sampling, combined with in-situ measurements of water properties, showed that yellowtail scad favor rocky reef areas where upwelling has occurred. Otolith microchemistry (Ba, Sr, Li, Mg, Na) showed evidence for two separate populations of yellowtail scad within the MPA: a slow-growing population that remained resident in the inner region of the MPA over our two year sample period, and a faster growing population in the outer bay. New data on pelagic fish meta-population structure, home range size and habitat preferences can be used to ensure that MPAs protect resident populations across their home range and protect migratory populations in areas where their habitat is predictable.

The giant kokopu (Galaxias argenteus) is an endemic diadromous fish species that is considered threatened, which has been partially attributed to habitat loss. During this study we aimed to evaluate whether giant kokopu in urban streams in Hamilton, New Zealand, was habitat or recruitment limited by habitat restoration and fish release. Habitat was enhanced in ten urban streams by introducing 20 clay pipes or 10 ponga fern (Dicksonia squarrosa) logs into two 20-m sections of each stream, and leaving a third upstream section unmodified to serve as a control. Thirty marked, farm-reared juveniles were released into each of five streams in April 2007. Survival of the released fish, as well as any wild fish, is being monitored to establish the success of the fish releases under the different habitat treatments. Preliminary results indicate a survival rate of released fish of at least 16% over 19 weeks, with an average growth rate of 27 mm or 44% in some of the stream sections.

The Oxleyan pygmy perch Nannoperca oxleyana is a small freshwater fish endemic to the coastal lowlands of central-eastern Australia. The species is currently listed as endangered at an international, national and state level. Detailed species’ specific information is required to assist in planning and implementing effective conservation management programs for N. oxleyana. An overview is provided on PhD research into several poorly understood aspects of the species’ conservation biology. Aspects discussed include the evaluation of appropriate methodologies for sampling the species, and the species’ distribution and habitat associations, genetic population structuring, reproductive biology and early development. The results of this research have important implications for the conservation of N. oxleyana in Australia. A number of management recommendations proposed.

Macquaria is an endemic freshwater fish genus that is of importance to Australian fisheries management. Macquaria ambigua is widely distributed across central and eastern Australia (Murray-Darling, Lake Eyre, Bulloo and Fitzroy basins) and is a prized recreational fishing species that has been stocked throughout most of its range. On the other hand, Macquaria australasica has a restricted distribution in eastern Australia (Murray-Darling, and some south eastern NSW coastal basins), is classified as vulnerable in New South Wales and stocking activity has been limited. This project aims to elucidate the historical patterns of population genetic structure and diversification in both species. It will identify distinct evolutionary units, and assess the effect of fish stocking on the genetic diversity and structure of populations. In order to achieve these aims a comprehensive collection of samples has been obtained from across each species range. Mitochondrial DNA (mtDNA) sequence data has been used to reconstruct the genealogical history of both species based on coalescence methods, the results of which will be presented here. This research has important implications for the management of M. ambigua and M. australasica, and fisheries management in general.

The nationally endangered Macquarie Perch (Macquaria australasica) was formerly present in a number of streams in the Canberra region including the Murrumbidgee, Cotter, Paddys, Molonglo, Queanbeyan, Goodradigbee and Paddys rivers. Monitoring of the Murrumbidgee population in the ACT demonstrated significant declines occurred in the mid-1980s. The Queanbeyan River population declined following the construction of Googong Reservoir in 1978. Information on the Paddys River population is more sketchy, but had declined to negligible levels by the late 1980s. The Goodradigbee population declined somewhere between the mid 1980s and the mid 1990s, and is now below detectable levels, and the Cotter River population is thriving over a very restricted geographic range. Translocations in the Queanbeyan and Cotter catchments in the 1980s met with mixed success, and the only viable ACT population of the species now exists only in the lower Cotter River, where a large new impoundment is planned. Viable populations also exist in the upper Murrumbidgee River above Cooma. A new program to establish additional populations around the ACT commenced in 2006, and will be outlined in this presentation.

Orange roughy Hoplostethus atlanticus, is a deepwater species inhabiting southern Australian waters. It is of high commercial value, long lived, slow to mature with low fecundity and forms dense spawning aggregations; attributes that render it vulnerable to fishing. Five stocks are currently recognised for assessment and management purposes within the Australian Fishing Zone. Targeted fishing by Commonwealth licensed trawl operators for orange roughy peaked in the late 1980’s and despite management efforts to limit catches throughout this period, these were not adequately constrained and began to decrease. In 2006, four of the five stocks were classed as overfished. In November 2006 the Minster for the Environment and Heritage listed orange roughy as conservation dependent under the Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act). This was the first commercially harvested species to be listed under the EPBC Act. The decision by the Minister not to list this species under a higher category was due to the Australian Fisheries Management Authority having already established a Conservation Program for the species. In this paper we outline the Conservation Program established for orange roughy and discuss the implications.

Marine reserves are being widely implemented as a tool for fisheries management and biodiversity conservation. Although the siting of marine reserves often includes a surrogate measure of diversity, the precision of these measures is rarely tested. To create the marine park at Lord Howe Island, habitat was used as a surrogate for community diversity. The aims of this study were to test the precision of habitat in predicting reef fish assemblage structure, and to investigate changes in precision when varying resolutions of baseline habitat data were available. Visual counts of reef fish species and habitat surveys were conducted at 31 sites. Overall, the variations in fish assemblage among sites were moderately correlated with habitat variations, while fish assemblages were weakly spatially auto-correlated, strongly affecting sites within a proximity of 1 km. The ability of habitat classes to predict reef fish assemblage structure was dependent on the quality and quantity of baseline data. Differences in assemblage structure were found among habitat classes derived from detailed high-resolution data, but not among habitat classes defined from low-resolution data. This study highlights the need for accurate in situ ecological information to establish precise habitat surrogates to more effectively site marine reserves.

The use of off-channel anabranch habitat by Murray Cod Maccullochella peelii peelii was studied in the Mullaroo Creek/Lindsay River system, north-western Victoria between 2004 and 2006. Seventy one Murray Cod of varying sizes were captured from the Mullaroo Creek anabranch, Lindsay and Murray rivers. All fish of suitable size were radio-tagged to enable movements to be monitored. Results indicate that the high density of Structural Woody Habitat (SWH) and high velocity habitat found within the Mullaroo Creek system support an exceptional population of Murray Cod compared to nearby Lindsay and Murray River habitats. Most importantly, prior to the breeding season, mature size Murray Cod from the Lindsay and Murray River were recorded to migrate upstream into the upper Mullaroo Creek system where they remained for a considerable period of time before returning to their “home range” habitat downstream. Conversely, individuals with a home range within the upper Mullaroo Creek remained at this site during the spawning period. Spawning site fidelity was clearly recorded over consecutive years for individuals migrating upstream into the upper Mullaroo Creek reach. These results indicate a selection for this habitat within the Lindsay/Chowilla floodplain habitat.

The giant Australian cuttlefish (Sepia apama) forms an annual breeding aggregation at Whyalla (South Australia) that comprises more than a quarter of a million individuals, a phenomenon not known in other cephalopods. An appropriate strategy for managing this species is required including knowledge on the population structure. It has been suggested that the best approach to determine population structure is to use a combination of complementary methods that address different aspects of the biology of a species. Molecular, chemical and morphometric techniques were used to determine the population structure of S. apama in South Australia. Results from the three techniques are in agreement and indicate that the breeding aggregation in Whyalla is one of two significantly different populations of S. apama in South Australia. A potential third population may exist in the region between the breeding aggregation and Gulf St Vincent, however, levels of differentiation between this population and Whyalla are different from year to year. Findings are of importance for the management of S. apama, in addition to increasing our understanding of the species dynamics and evolution. The presence of at least two populations means that S. apama in South Australia must be managed as separate populations.

The Atlantic cod Gadus morhua L. persists over a wide range of thermal environments and within this range the population exhibits spatial structuring. Populations may exhibit local adaptation in their life history traits in response to their environment. Experiments are reported in which life history responses in relation to temperature were investigated in three populations that differ in their thermal regime. Post-settled wild cod from the east and west coasts of Scotland and the southern North Sea were investigated under controlled environment conditions. The populations differed in their juvenile growth rate, in their reproductive development and in their competitive interactions. Juvenile west coast cod maintained higher growth rates than east coast cod across a range of temperatures. First-time spawning west coast cod were more fecund for a given size than east coast and southern North Sea cod. Higher temperatures led to higher growth rates and a greater final body size, which enhanced fecundity. Studies of juvenile aggression in relation to population and haemoglobin genotype give insight into the mechanisms behind these life history differences. This mounting evidence of local adaptation should enable better estimates of fish population dynamics at biologically appropriate spatial scales and in response to changing environmental conditions.

Abalone populations are known to vary greatly in growth rate, size at sexual maturity and asymptotic length across their range. It is hyptothesised that elements of shell shape may relate to the growth rate and fecundity of abalone and may be a valuable management tool in identifying areas at risk of depletion, and those that are under-utilised. We tested this by sampling abalone populations from across Southern Australia in Spring 2006 to investigate the relationship between shell shape and fecundity at sites with different growth rates. Several parameters of shell shape were found to correlate strongly with growth rate with sites of slow growth tending to yield higher, rounded shells than fast growing sites. Animals with more domed shells also tended to have larger gonads than those with flat shells. We discuss the importance of these data in relation to local scale management of abalone stocks.

This paper discusses how spatially appropriate management can be implemented in fisheries through user-participation in management. This is examined using a case-study of the Victorian abalone fishery. The central and western regions of this fishery have developed a reef-scale approach to management; an arrangement whereby resource users collaborate with fishery scientists and government managers to set harvest rules at finer spatial scales than feasible under a government system alone. Drawing on the extensive body of work on common-pool resource theory, rational-choice models of human behaviour and the emerging concept of social capital, the present paper examines the social factors that underlie the development of such an arrangement. The abalone fishery, when viewed from this social science perspective, seems to be highly suited to collective action, with a small group of resource users and a resource that is suited to relatively well-developed property rights. The role of government in such arrangements is also important, and it is suggested the formal power of management agencies can be synergistic with user-derived rules. The iterative, ongoing nature of the collaborative process is also important, but pertinently suggests that developing the capacity for management can be a lengthy process, heavily reliant on the building of social capital.

Snapper (Pagrus auratus) collected from the Eastern Gulf, Denham Sound and Freycinet Estuary areas of Shark Bay were used to investigate spatial variation in life history characteristics including maximum age, growth, maturity and spawning time. The peak spawning period occurred at different times in each area and varied in duration. Maximum observed ages were 17 years in the Eastern Gulf and Denham Sound compared with 31 years in the Freycinet Estuary. There were significant differences in both length and age at maturity between sexes within each area and for both sexes among areas. Sex-based differences in growth within areas were not significant, however, when lengths at age were pooled and compared among areas, growth in Denham Sound was significantly different to that in the Eastern Gulf and Freycinet Estuary. This fine-scale variation in life history characteristics, while unusual for a large, potentially mobile sparid, inhabiting a marine environment with no obvious physical barriers, is linked to the Bay’s marked environmental heterogeneity, low levels of mixing and historic differences in fishing pressure. Results are consistent with previous stock identification studies and add further support for the geographic scale at which local snapper stocks and the recreational fishery are managed.

It is widely recognised that abalone fisheries consist of numerous populations with variable life history parameters. Current broad-scale management regimes do not account for this variation and can lead to serial depletion of separate populations. However, the ability to manage abalone populations at fine scales is limited by our knowledge of the scale at which abalone ‘populations’ exist.

Morphometric data collected from 8- broad and 8 fine-scale sites in the Southern Zone Abalone Fishery of South Australia (SZ), suggest that a shell length/shell height ratio can discriminate among populations that show ‘stunted’ and ‘non-stunted’ patterns of growth. Moreover, biological information collected in conjunction with the morphometric data revealed that the spatial variability of this ‘morphometric marker’ was highly correlated to that of growth and reproductive biology. The ‘morphometric marker’ was applied to commercial shell samples collected across the SZ to identify the spatial distribution of ‘stunted’ and ‘non-stunted’ populations. Several decision rules were used to identify how this information could be used to potentially alter current management arrangements in the SZ.

Recent advances in mapping of deeper marine environments using high resolution hydroacoustic surveying and detailed predictive marine habitat mapping has facilitated more targeted marine management and research. In 2005, a joint venture between Parks Victoria and the Coastal CRC resulted in detailed habitat maps of five of Victoria’s Marine National Parks. At Cape Howe Marine National Park we used one of the resultant habitat maps to plan and conduct a survey of demersal fish using Baited Remote Underwater Stereo-Video Systems (Stereo BRUVS). We chose to use stereo BRUVS as a sampling tool because they are non-destructive and are able to collect comparable data on the diversity, relative abundance and length of demersal fishes from shallow (~ 10m) and deep (~100m) benthic habitats. In addition, the technique provides accurate and precise measures of sample boundaries imperative for spatial analyses.

The aim of this research is to identify key biotic and abiotic processes influencing the spatial distribution of demersal fish species. Outcomes of the project will include a greater understanding of demersal fish distributions, assemblage structure and landscape linkages, and will assist with more targeted fisheries management and marine protected area planning and development.

Fuzzy rule-based models are more transparent than their statistical counterparts. Their suitability to develop universal approximators facilitates the development of first pass predictive models. They can combine quantitative and qualitative information typically embedded in human knowledge. They are well suited to modeling complex systems when the nature of the data is incompatible with the time and effort required by a more sophisticated statistical approach. The availability of stable freeware, abundant literature and a growing interest among fishery researchers are strong incentives to consider fuzzy logic as a complement to more established statistical methodologies in fishery management.

In an FRDC funded project (2005/047) fuzzy logic was used to capture fisher’s knowledge for the purpose of developing a local model of fishing power in the Timor Reef Fishery (TRF). A fuzzy expert system of intrinsic vulnerability of commercial species to fishing pressure was implemented from the literature. Results obtained for the main target species of the TRF were validated by international experts.

The lower west coast demersal scalefish stocks in WA are exposed to a range of factors that vary spatially. The west coast bioregion stretches over 900 km of coastline along a latitudinal gradient (27° S to 34° S) including the capital city of WA, Perth. This multi-species fishery comprises species with variable distributions and abundances as well as exploitation levels. A three-year FRDC-funded research project examined regional variations in stock structure, age and growth and reproductive biology of the two key species; the endemic West Australian dhufish, Glaucosoma hebraicum and the nationally widespread snapper, Pagrus auratus.

Despite both species being large, long-lived demersal fish exposed to a similar environment, many aspects of their biology varied. The timing of the onset of reproduction in snapper varied regionally in relation to the water temperature gradient. In contrast to snapper, dhufish showed highly variable recruitment but few spatial patterns in biology as most of the regional variability in the biology of this species was due to the difference age classes. Lastly, results of isotope analyses of whole otoliths showed that adult dhufish are lifetime residents of their particular geographical location, whereas snapper sub-adults appear to be well mixed throughout the bioregion.

The West Coast Demersal Scalefish Fishery covers over 900 km of coastline along a latitudinal gradient (27°S to 115°30′E) including, Perth, the capital city of Western Australia. This multi-species fishery comprises species with naturally variable distributions and abundances as well as differing exploitation levels by commercial, charter and recreational fisheries.

Regional stock assessments of three key indicator species (dhufish, pink snapper and baldchin groper) have been undertaken. However in these fisheries the spatial and temporal data are limited (e.g. lack of relevant catch and catch rates) and it is not possible to develop models that can estimate stock abundance. In these circumstances, a ‘weight-of-evidence’ approach was considered best practice to assess the status of a stock. This approach individually examines any quantitative measures that may be available (e.g. estimates of fishing mortality) and considers these holistically with species biological characteristics (e.g. natural productivity, habitat requirements etc.) in conjunction with any operational characteristics of the fishery plus the potential influences of environmental changes.

Results from the regional stock assessments and the management implications are presented.

Resource allocation in the marine environment is becoming an increasingly contentious issue and often the areas of dispute are on relatively fine spatial scales. Therefore it is important to develop tools which allow analysis of information on a small spatial scale in a way which can be understood by a variety of stakeholders, often from very different backgrounds. The visual nature of GIS make it an ideal tool to effectively engage all stakeholders, while spatial statistics allows spatial data to be analysed in a spatial environment. Although GIS spatial statistical methods require a high level of expertise, the visual nature of these techniques allows stakeholders to understand the results in a more intuitive way and engage more fully in the decision making process.

We present a case study from the Timor Sea between fishers and two gas companies where these methods assisted in identification of the issues, what further research information was needed and what scope there was for modifying operations. These techniques could be equally applicable to other situations or fisheries.

Using a GIS driven analysis we combined bathymetry, geomorphic units and 10 years of fishers’ catch records from the Timor Reef Fishery (TRF) to produce a spatial model of productivity within the TRF. The productive zone is only a fraction of the fishery. And consequently intense localised impact can dramatically affect fishers’ income. A 3D seismic survey in the most productive zone of the fishery prompted an assessment of the impact on the fishery. Historical data demonstrated variability in seasonal production to be incompatible with meaningful comparisons between successive years. Refusal by the gas company to fund an independent survey lead to logbook data being the only available information to compare fishers’ catch simultaneously recorded inside and outside the survey area.

The assessment of fishers’ catch records, based on the non parametric Kolmogorov-Smirnov test suggested that the seismic survey negatively impacted fisher’s commercial activities, although this is disputed by the gas company. Two separate independent expert statisticians contributed their expertise to the interpretation of fishers records. This case highlights advantages of GIS based fishery management strategies and the inability of standard statistical methods to easily incorporate crucial ecological information.

Sometimes the data considered to determine stock status can be temporally or spatially limited, whereas considering a modern fishery in a broader temporal and/or spatial context can be very informative. The South Australian fishery for southern sea garfish (Hyporhamphus melanochir) experienced a significant downturn in the early 2000s. Two alternative hypotheses were proposed to account for this, i.e. natural population dynamics or recruitment over-fishing. This study helped to differentiate between these by: considering the history of the fishery; determining the level of exploitation in the modern fishery; and describing the contemporary population structure and assessing whether population truncation had occurred due to fishing.

Catch records indicated that the fishery had sustained substantial catches for at least 60 years. Exploitation rates for the modern fishery, estimated using a complex, computer fishery model, have generally exceeded 50% of the fishable biomass. Population structure in 2005/06, determined by market-sampling and fish ageing, was dominated by one- and two-year old fish. There is strong evidence of population truncation, compared with results from similar sampling in 1954/55 as well as lightly-fished, geographically-separated populations. In 2005, the fishery status reflected; its long history, high exploitation rates and population truncation.

Fisheries managers rely on readily available and reliable data, together with the efficient analysis and interpretation of those data, to provide an accurate picture of fishery use and fish stock status. Many issues for fisheries managers are related to the spatial distribution of species catches and fishing activity. To meet this need, the Australian Fisheries Management Authority (AFMA) developed a reporting environment that uses Hyperion Business Intelligence, ESRI ArcIMS and Integeo Map intelligence to provide a flexible reporting and mapping environment via an intranet portal. This system provides an extra dimension to the information capabilities of fisheries managers at AFMA.

The future of Pacific island subsistence and market economies is tied to the health of the freshwater, cooastal and oceanic systems of the region and the long term sustainability of their fisheries. In the smaller island and atoll states in particular, where there is very little land, there are few other opportunities for economic development. For some countries, commercial fisheries are possibly the only sector with that potential. An overview of the development and priorities identified in AusAID’s An Ocean for Growth and Stability – valuing Pacific Fish is given. There significant are significant strengths in Australia in marine science, in fisheries research and management agencies and in the industry. There are opportunities to contribute in addressing some of the impediments in the development of sustainable aquaculture and freshwater and marine fisheries in the region.

The Gulf St Vincent Prawn Fishery was first harvested commercially in 1968. Exploitation increased rapidly and reached >600 t during 1975/76. Both catch and effort declined steadily thereafter until the fishery was closed in 1991 due to the poor state of the biomass. Fishing resumed in 1993 and catches again increased until 1999/2000 when catches reached 400 t. However, catches and biomass declined again over the next four years caused by a combination of factors including increasing exploitation rates that exceeded the increases in biomass after the closure and the targeting of high catches of large fecund females, particularly early in the spawning season. In December 2004, a program which required fishery-independent surveys to be conducted prior to the commencement of each of the four main fishing periods was established at 110 sites throughout the fishing grounds. Survey sites were trawled for 30 minutes during each survey. Data on catch rate (index of biomass), size structure and recruitment were collected. This information was used to determine conservative, spatially explicit harvest strategies. In the three years since this program was conceived, survey catch rates have increased by approximately 70% and total annual catch has increased from 160 t to 240 t.

Estuarine fauna, flora and structure are subjected to extremely unstable environments caused by the physical and chemical changes that occur when freshwater flows enter estuaries. Within Australia, the development of water plans pertaining to river catchments have recently included the need to monitor the “health” of estuaries. In Queensland, one of the indicators suggested to monitor estuarine health within water plans was estuarine fisheries production. Fisheries production is often the only long term measure of the economic benefit of estuaries while also reflecting the environmental state of the estuary. Using a logical decision making framework to determine the appropriate temporal and spatial scales, we have shown that fisheries production and freshwater flows are highly correlated in time and space. Various measures of estuarine fisheries production were investigated, with decadal catch data, yearly recruitment indices, monthly growth rates and short term movement all being significantly and positively influenced by freshwater flow entering the estuary. We suggest that freshwater flows bring long and short term benefits to estuarine fisheries through enhanced biological productivity.

Fish communities across the Queensland Lake Eyre Basin were sampled in April 2007. Flooding preceded the sampling in both the far east (Bulloo River) and far west (Georgina and Mulligan Rivers) of the Basin. In contrast, the Diamantina and Cooper catchments did not experience major summer flooding. The sampling undertaken indicates that previously dry waterholes are likely to be re-colonised en masse by juvenile fish of several species following periods of hydrological connectivity, and that waterholes in central Australia, though ephemeral, are utilised as fish nurseries when water exists. In addition, range extensions were recorded for golden goby, Glossogobius aureus, in the Diamantina catchment, redclaw crayfish, Cherax quadricarinatus, in the Georgina catchment and seven fish species in the previously unsurveyed Mulligan River, which forms the north-eastern boundary of the Simpson Desert.

The southwest of Western Australia contains a depauparate, but highly endemic freshwater fish fauna. A major environmental problem impacting on freshwater fishes in this region is secondary salinisation, resulting from land clearing in the upper catchments. Although salinisation has severely restricted the distribution of a number of species of freshwater fish, some, such as the Western Minnow, Galaxias occidentalis, are more salt tolerant and retain a wide distribution throughout the south west. We know very little, however, about the effects of increased salinity on the biology of these salt tolerant species. We studied a number of biological parameters of populations of G. occidentalis in fresh, brackish and saline reaches of the Blackwood River in the south west of Western Australia. Salinity appeared to have significant effects on the size distribution and diet of G. occidentalis.

Dissolved oxygen levels low enough to impact upon aquatic fauna are common, especially in warm tropical wetlands. Dissolved oxygen is one of the most commonly measured water quality parameters in the field, but the lack of knowledge of faunal tolerances to low dissolved oxygen (termed hypoxia) restricts interpretation of the observed concentration values. We tested the laboratory hypoxia tolerance of 15 fish and one crustacean species from northern Australian freshwaters. Our rapid testing protocols allow a large number of tests to be completed in a relatively short time frame and allows for video recording of various behavioural and physiological responses to progressive hypoxia. The tests included gill ventilation rate tests and relative oxygen consumption rate, demonstrating lethal and sub-lethal effects on fishes across a range of size classes. Many fish species have surprisingly low lethal thresholds, often below 20% or even 10% saturation. The most sensitive species tested were banded grunter, fly-specked hardyheads, eastern rainbowfish and Pacific blue-eyes. Fish size and water temperature both had significant effects on tolerance levels. Data from these tests has been used to recommend revised water quality guidelines for dissolved oxygen with default chronic and acute effect trigger values of 75% and 30% saturation respectively.

Environmental variables can take a pivotal role in structuring fish communities, with the distributional limits of species often being shaped by interactions between their physiology and the physical attributes of their environment. Recent research on pectoral-swimming fishes revealed a strong link between the swimming abilities of species and their distribution across wave energy gradients. Species capable of high sustained swimming speeds dominated wave-swept, turbulent habitats, whereas slower swimmers were either rare or restricted to sheltered locations. While this among-species relationship has now been established for over 100 species occupying both tropical and temperate reef systems, the potential for a single species to adapt their swimming abilities to suit their local environment has remained largely unexplored. This study examined intraspecific variation in the swimming abilities of fishes distributed across a 50 km gradient of wave energy on the Great Barrier Reef. I will discuss the mechanisms that may have given rise to such patterns and explore the wider implications for our understanding of morphological diversification in fishes.

Understanding the association of fish recruitment and flow is necessary in the management of regulated rivers in coastal regions of Australia where there is increasing human demand for water. This study compares fish assemblages and recruitment in two regulated and two nearby unregulated tributaries of the Hunter River sampled monthly using sweep net electrofishing between August 2006 and June 2007. The regulated tributaries have fewer small pulses or ‘freshes’ throughout the year compared to the unregulated tributaries, although large floods still occur at similar frequencies. I predict that these changes in the flow regime will affect both the timing and success of fish spawning, thereby influencing fish assemblages. Flow regulation did not affect fish assemblages during spawning, but appeared to influence post-spawning recruitment. Peak spawning of two abundant species, Australian smelt (Retropinna semoni) and Cox’s gudgeon (Gobiomorphus coxii), was delayed in regulated tributaries compared to unregulated tributaries. Potential mechanisms underlying these patterns include reduced parental fitness and/or delayed maturity due to altered availability of prey or changes to water temperature downstream of dams. Outcomes of this study will have implications for the development of environmental flows in coastal rivers of temperate Australia where flow regimes continue to be regulated.

Fish living in the Moonie River, must cope with a range of environmental stresses associated with the unpredictable and highly variable hydrological regime of this dryland river. To investigate spatial and temporal variability in fish condition in the Moonie River we examined tissue lipid and water content of two ecological generalists: bony bream (Nematalosa erebi) and yellow belly (Macquaria ambigua) on three occasions (February, May, September 2006) in disconnected waterholes following summer flooding in January 2006. We predicted that fish condition would be highest in February due to the feeding benefits provided by flooding and condition would diminish thereafter as waterholes dried and food resources became limiting. We also predicted fish condition would vary among waterholes due to site-specific differences in waterhole physical character. Preliminary analysis revealed that fish body condition results were dependent on fish size. Larger bodied yellowbelly and bony bream individuals (>80 mm S.L.) had the best (fattest) body condition in February and their condition worsened thereafter. The condition of small (<80 mm S.L) yellowbelly showed little variation over time, while small bony bream were fattest in May 2006. In general, fish condition was not related to waterhole physical character, however bony bream were fatter in waterholes with a weir structure compared to waterholes with no weir structure, while the opposite trend was apparent for yellowbelly.

The flyingfish fishery is an important marine commodity in Indonesia, especially within south Sulawesi. The fishery in south Sulawesi has been very popular since the late 1970’s due to a high demand on the international market for flyingfish roe, most of which has been exported to Japan, Taiwan, Hongkong and Korea. Early this century, fish production decreased and over exploitation of flyingfish in south Sulawesi became a major issue. Between 1980 and 1990 an ongoing study of flyingfish fishery was focused on the south Sulawesi region only, but since 2004 apresent day study has been extended to Maluku, North Sulawesi, Bali, Lombok and west Sumatera as the fishery has also extended into these regions. The main objectives of this study were to understand diversity, distribution and abundance of flyingfish within Indonesian waters, and reproductive biology and length frequency data were also observed for more abundant species. Samples were taken regularly from landings, and 11 of 13 identified species were found in the south Sulawesi region, identifying this region as a hotspot for fyingfish diversity. Cheilopogon cyanopterus, C. suttoni, Hirundichthys oxycephalus and Parexocoetus mento were abundant and widely distributed. The results from this study will eventually be used to establish a management plan for sustaining the flyingfish fishery of Indonesia.

The Queensland DPI&F Long Term Monitoring Program (LTMP) commenced monitoring rocky reef fish in July 2006. The fishery-dependent program uses a range of sampling strategies to collect length, age and sex data representative of the retained catch of multiple sectors of the rocky reef fish fishery. The sampling strategies and sampling events are not limited to rocky reef fish, but are also used to collect data for a number of other finfish fisheries monitored by LTMP. Target species from the rocky reef fish fishery include snapper (Pagrus auratus), pearl perch (Glaucosoma scapulare) and teraglin (Atractoscion aequidens). Data on several other species, including black kingfish - ‘cobia’ (Rachycentron canadum), amberjacks (Seriola dumerili, S. rivoliana, Seriolina nigrofasciata), Samson fish (Seriola hippos), and yellowtail kingfish (Seriola lalandi), are collected opportunistically. The shared sampling strategies include: “commercial catch sampling” either directly from fishers or at seafood processors; “boat ramp surveys”; “charter boat catch sampling”; and a “keen angler program”.

Diel activity of two threatened freshwater fishes, a palaemonid prawn and an atyid shrimp, was established from remote underwater video in a pool of an upland stream (Australian Captial Territory). Both threatened fishes, Macquarie perch (Macquaria australasica) and two-spined blackfish (Gadopsis bispinosus), were diurnal while in the early-juvenile-phase (< 5 cm total length (TL)). In contrast, larger fishes (> 5 cm TL), shrimps and prawns were crepuscular and nocturnal. Additionally, subsampling of video was shown to be an efficient means of establishing the diel activity patterns of early-juvenile-phase fishes. The suitability of using underwater video to quantify short-term (seconds) behavioural interaction between individuals was also demonstrated, with early-juvenile-phase G. bispinosus exhibiting interference competition on 35% of occasions when two or more individuals were observed. An attempt to investigate trout predation on early-juvenile-phase M. australasica was unsuccessful, as these species were not recorded simultaneously. This study demonstrates that remote underwater video is a useful method for observing the in-stream behaviour of threatened freshwater fauna where other techniques are not viable.

Sampling programmes for monitoring threatened species require some repeatable and semi-quantitative sampling strategy to provide reliable estimates of population density and long-term demographic trends. However, quantitative sampling in low-density populations or highly heterogeneous habitats represents a considerable challenge. We have attempted to quantify the required sampling effort for monitoring populations of threatened mudfish using Gee minnow traps from 12 years of field data and controlled, replicated laboratory studies of Gee minnow trap efficiency. Conservation managers need to define the required measure of data precision necessary to obtain useful measures of long-term population trends. The application of a prescribed sampling design needs to consider not just population density and catch precision and variation, but also capture efficiency and fish behaviour.

The Greater Sydney Region covers a large area, stretching from Newcastle southwards to the Illawarra area. This area contains the three largest cities in NSW and a great number of the state’s recreational fishers. A series of concurrent on-site surveys are currently underway throughout the region. These surveys have been designed to provide site specific, baseline data on recreational fishing effort and catch within the region. On-site survey methods have been used because they provide validated information on: (a) patterns of fishing effort; (b) species composition of the harvest; and (c) size structure of fish populations targeted by recreational fishers within the region. The survey work started in March 2007 is scheduled to continue for a two year period. I will provide an overview of this project and discuss the utility of these survey data for assessing potential environmental and anthropogenic impacts.

We reviewed the efficiency of the current sampling protocol data for the QLD DPI&F Long Term Monitoring Program with regards to the number of fish species collected. The majority of sites are not exhaustively sampled in any given year but cumulatively almost all of the sites have had 90% or more of their species recorded. The Daintree, Johnstone, Mitchell and Noosa rivers however may have up to 20 species still to be collected. There was very low probability of returning complete species inventories for any of the rivers on any year using the current protocol of seven sites per river. Individual sites within the Condamine were efficiently sampled on any given date and the Warrego river the least likely to have new species in future sampling. If the number of sites were to remain fixed then 9 shots per site would return a more complete species list for most rivers. It would be possible however to adjust the effort at sites independently to avoid over-sampling some sites and under-sampling others. The results are probably influenced by the coastal rivers being under-sampled if they include estuarine sites. Overall, the data have been under-utilised and are a valuable resource that could be put through a suitable bio-monitoring framework for these rivers.

The Queensland Department of Primary Industries and Fisheries (DPI&F), Long Term Monitoring Program (LTMP) routinely estimates age for a large number of fin fish species. The most common and important application of these age data is to provide information for stock assessments to determine the status of fish stocks. A Microsoft Access Application “Queensland LTMP Fish Ageing Software” has been developed to facilitate staff training using otolith image reference collections, and the reading of current samples. The application handles an original and current reference collection for multiple fish species.

The Queensland LTMP Fish Ageing Software covers each of the steps described in the document
Department of Primary Industries And Fisheries (2007). Fisheries long term monitoring program sampling protocol - fish ageing section 1. department of primary industries and fisheries, Brisbane, Australia. The application also has some functionality to assist with the maintenance of the otolith image reference collections and the reviewing of historical training reads and readings of current samples. The application was developed for otolith reading and is easy to adapt e.g. can be used for different species, different reference collections and makes results from quality control tests easy to understand for age readers.

Zoning and ‘rights to access’ have been a feature of fisheries since the earliest recorded civilizations. More recently, fisheries managers have used spatial management to various degrees, and virtually all management plans implicitly use some form of spatial management for a variety of purposes. Until recently the focus has been on target species and maximizing yields. However, there has been increasing community concern about the wider ecological impacts of fishing resulting in moves to ecosystem based fisheries management. Explicit spatial management (including closures) has also become a key requirement for a number of Australian fisheries arising from strategic assessments under the EPBC Act. There has also been an increasing focus of fisheries management at finer spatial scales. In addition, in response to a perceived failure of traditional fisheries management, there have been frequent calls for widespread use of MPAs (primarily no-take zones) as fisheries management tools. Management of other marine uses, which can impinge on fisheries, similarly use spatially-based governance and management arrangements. So how effective are these policy directions likely to be in achieving the objectives of fishery management?

There has been a relatively rapid development in tools to support these policy drivers: VMS, electronic tags, UVS, ecological risk assessments and spatially explicit resource and ecosystem models are some examples. Not withstanding this, the policy development still runs ahead of the scientific tools and methods to support it. The potential for fishery closures to protect upper slope gulper sharks is discussed as an example of the use of spatial management to mitigate the effects of fishing, highlighting current gaps in understanding and future research needs. More generally, the results of a recently completed ‘whole of fishery’ MSE study demonstrate the importance of considering spatial management as one of an integrated set of management ‘levers’ for successful fisheries rather than as a ‘panacea’ to solve all fishery management issues.

The Australian Ocean Data Network (AODN) will enhance access to, and re-use of, Australian marine science data and data products, by ensuring standards-of-practice across the marine science data management community, and providing a one-stop-shop for marine science data access, using the foundation architecture and services of the Oceans Portal and MEST (Metadata Entry and Search Tool). The AODN offers a single, standards-based, distributed and federated marine science data network. It builds on existing collaborative relationships, agreements, and infrastructure including the existing “Virtual Hosting Repository”, which offers archiving, ready discovery and access, and delivery of marine science data from a wide range of funding schemes, and from organisations and individuals in both the government and higher education sector. Two projects of interest are BlueNet and the e-Marine Information Infrastructure Project (eMii). BlueNet is assisting Australian universities to link to the AODN through the development of software, outreach to partner universities and through collaboration with AODN agencies and other virtual repositories (e.g. OBIS). eMii is the data management component of the IMOS (Integrated Marine Observing System) program. Using an integrated standards-based approach across a range of marine science disciplines will, for the first time, drive a new generation of approaches to data management and sustainability.

Extensive and intensive debate on the uses of MPAs around the world has converged on acceptance that well designed and implemented area management can be an extremely useful tool for biodiversity conservation. But this same debate increasingly highlights the pitfalls of assuming that closing areas to fishing will automatically provide protection and benefit fish resources. Benefits to efficient fisheries management from area closures remain even more elusive. Sedentary organisms tend to respond well to protection of components of their total distribution, while the management of more mobile species is often not aided by restricting catches over parts of their habitats.

The pros and cons of MPAs as a fisheries management tool are still hotly contested. Opposing views can not all be correct. Unfortunately some views remain based on inadequate science or misrepresentation of the available evidence. People who have been misled, for whatever reason, by biased misinformation have been hoodwinked.

It is generally acknowledged that considerable improvement in fisheries management is essential if the world's capture fisheries are to produce optimum returns. Fisheries science has often not been compelling and management and industry have exploited the resulting uncertainty for short-term gains, often at the expense of sustainability. However, exploitation of imprecise or inadequate 'science' in the interests of unjustified restrictions on fishing is no more acceptable, and often no less destructive of the interests of ecologically sustainable development. Assertions based on inadequately peer reviewed science can harm not only efficient management but also the credibility of scientists and the organisations for which they work. Management actions based on incorrect assumptions harm the long-term sustainability of biodiversity itself.

Documentation used to support the recently declared Batemans Marine Park is used as an example of the quality of science on MPAs in NSW and the impact of this science on policy and management.

Questions are raised on the possible role of ASFB in protecting the standard of fisheries science in Australia and the reputations of our scientists.

The large yellow croaker was a commercially important marine fish in the East China Sea between the 1950s and early-1980s. Catches from the sea declined by 99% within just 2 decades and there is no sign of stock recovery; this would categorize the croaker as ‘threatened’. Management measures and mariculture have been developed in China, and most individuals subsequently sold originated from hatcheries during the last decade. We integrate exploitation history to trace the collapse of the croaker and assess the role of mariculture and restocking in wild stock recovery. A combination of poor management, heavy exploitation of spawning and over-wintering aggregations, and pollution and habitat degradation were the major factors in stock decline. Although the croaker proved a highly successful mariculture candidate with approximately 70,000 mt produced in 2005, a quarter of all Chinese marine finfish culture, mariculture and restocking failed to adequately address the problems faced by wild croakers and resulted in biodiversity losses especially genetics. The detailed history of the croaker is a sobering reminder that successful mariculture is not necessarily a solution to overfishing, but a distinct means of seafood production that can compromise fishery recovery by competing for funds, attention and space.

The movement patterns of the endangered eastern freshwater cod, Maccullochella ikei, were studied over 12 month period in 2005 and early 2006. Radio tags were implanted in 25 adult cod (20♂; 5♀; mean = 529mm; range = 441-790mm) captured from three consecutive pools within the Mann River, northern New South Wales. Tagged cod were released in March 2004 with 18 (15♂; 3♀) monitored for 40 weeks and 13 (10♂; 2♀) for 50 weeks. Cod were located once weekly by boat, with flow and water temperature recorded using data-loggers. Automated tracking stations located at the intersection of pools recorded movements between weekly observations. Cod moved both upstream and downstream, and within pools as well as between pools. Total stream length occupied varied considerably (range = ♂211-34500m; ♀500-5700m) with no significant relationship between size of fish and home range (P<0.05). Average weekly movements of the tagged population varied significantly for both males and females (range = ♂36-1334m; ♀3-2417m). Inter-pool movement was facilitated primarily by flow, but was independent of water temperature. Increased activity during the breeding season was observed for males, but not for females. The maintenance of flows is paramount for the ongoing conservation of eastern freshwater cod, particularly during the breeding season.

The reproductive biology of the blue swimmer crab, Portunus pelagicus, was investigated in Wallis Lake, the largest fishery for the species in NSW. Crabs were sampled from fishery-dependent and -independent sources between November 2002 and July 2003. Mature female and male crabs were present in each month throughout study. Mature female (stage 5 gonads) were most prevalent in November, but there was no distinct pattern for males. The estimated size at which 50% of female and male P. pelagicus reached maturity was 46 and 44 mm CL, respectively. Fecundity of individual crabs was estimated to be between approximately 463, 000 and 1,781,000 eggs per brood. No significant difference in the CL - fecundity relationship was found for the two months examined (November 2002 and February 2003). The estimated number of egg broods produced (NBj) by female crabs in the different size classes ranged from one in crabs (50 - 55 mm CL) to three in crabs (75 - 80 mm CL). The reproductive biology of P. pelagicus is compared to reports from elsewhere throughout its distribution and implications for managing populations in NSW are discussed.

The elements contained within calcified structures of fish, molluscs, bivalves and corals may provide a means to determine the environment that an organism has occupied. In order to establish the possible environment of occupancy, it is first important to establish a link between one or more environmental variables and the concentration of elements within its calcified structure. To date, little experimental work has focused on statoliths, especially from cephalopods. Eggs containing prehatchlings, as well as recently hatched giant Australian cuttlefish (Sepia apama) were reared in different concentrations of strontium and barium at three temperatures. The concentrations of Sr:Ca and Ba:Ca in the statoliths were related to water chemistry, but the relationship varied with temperature. Uptake of elements will be compared between prehatchlings and hatchlings, and partition coefficients provided. These results indicate that it is possible to reconstruct the past environmental characteristics from statolith chemistry of cephalopods, based on the concentration of elements in the water. Establishing this link allows for the reconstruction of past environments that cephalopods have occupied based on elemental chemistry.

Dietary studies are critical to an understanding of elasmobranch ecology and the impacts of their loss (via fishing and by-catch) from marine ecosystems. The eastern fiddler ray (Trygonorrhina sp. A) is a common by-catch component of demersal fish trawls in NSW, but impacts of their removal are not known. Stomach contents of 102 rays (46 females, 56 males) collected from a commercial fishery operating near Newcastle in summer and autumn 2007 were analysed. Their broad diet was dominated (%W) by brachyurans, teleosts, cephalopods and penaeids. Significant changes in diet occurred between summer and autumn, with brachyurans typical of summer and penaeids typical of autumn. Significant size-based dietary differences were due to the variable dominance of different items among size classes: penaeids and amphipods (<20 cm DW), brachyurans (25 cm DW), and teleosts and cephalopods (>30 cm DW). Brachyurans were typical of all size classes. Significant sex-based differences were caused by varying consumption of diogenid, crustaceans, and cephalopods. Brachyurans and penaeids were consumed by both sexes. This study is the first quantitative analysis of the diet of Trygonorrhina sp. A providing an indication of their contribution to food webs and ecosystems.

Cadmium toxicity is species dependent and there is currently no data on its effects on juvenile western king prawns (M. latisulcatus). M. latisulcatus is an economically import species, supporting fisheries in both the Spencer Gulf and Gulf St. Vincent. The habitat of juvenile M. latisulcatus is the coastal intertidal, making them particularly vulnerable to anthropogenic disturbances and pollution e.g. stormwater run-off. The acid sulphate soils in the region, which when disturbed can lead to the leaching of heavy metals, including cadmium into the environment are also of concern. In order to establish benchmarks for future health and monitoring basic toxicity data such as LC50 through a 96 hour trial and LT50’s for Cd. Histology of the gills and hepatopancreas was also used to assess the degree of damage caused at various concentrations of Cd. Lipid peroxide was used to assess the level of stress caused by short term non-lethal exposure.

Long periods of barrier closure of ICOLLs make larval fish recruitment difficultfrom adjacent surf zones. By comparing assemblages of both environments it could be determined that certain fish do enter ICOLLs via various processes while using adjacent surf zones as accumulation areas. This study determined if there were any spatial or temporal variation between four ICOLLs and surf zone areas on the NSW central coast. Bimonthly, low tide, night sampling of surf zone areas adjacent, ~100m north and ~100m south of the mouth of ICOLLs as well as in the mouths of ICOLLs occurred from April 2006 to March 2007 using a larval seine net with 1mm mesh. Larval along with small adult and juvenile fish were collected. Clupeidae and Leptoscopidae were the most abundant families collected in surf zones while Ambassidae, Atherinidae, Eleotridae and Sparidae were the most abundant families collected in ICOLLs. Significant differences in fish numbers were found over time between ICOLLs and also between surf zone regions and adjacent, north and south areas. A difference in the families of fish collected between the two environments has shown that central NSW coast ICOLLs are not replenished by surf zone areas.

Northern Territory Fisheries legislation prohibits the harvest of Commercially Unsuitable Crabs (CUC’s – those crabs that have recently moulted and have a soft shell) by commercial mud crab fishers. This measure was introduced to reduce the high mortality rate of soft crabs, increase consumer confidence in the product (as soft crabs typically contain little or no meat) and maintain higher prices. Whilst the definition of a CUC is clear, it is qualitative rather than quantitative, a feature of some concern to industry. This work evaluates two commercially available durometers (instruments used to measure the hardness of a range of materials) as a means of quantifying shell hardness in mud crabs. Tests were undertaken on a variety of body parts, with the most useful being the second abdominal plate on the ventral surface for males and the forward quadrants of the carapace for females. Repetitive tests on the second abdominal plate of a male crab led to a 12% decrease in the durometer readings (through softening of the shell), suggesting that only the first few measurements can be used with absolute confidence. Durometer values were independent of both carapace width and wet weight for the range of sizes used.

A recent risk assessment identified that bycatch of the threatened Australian sea lion in the Commonwealth managed demersal gillnet sector of the Southern and Eastern Scalefish and Shark Fishery in South Australia, was likely posing a significant threat to many of the small subpopulations of the species. Given that there are limited options for gear-modification in this sector of the fishery, spatial management of catch and effort provides the only practical and immediate means for reducing risks to sea lion subpopulations. In response to this, we have developed models that enable the outcomes of different spatial distributions of fishing effort and the consequential risk-reduction benefits to individual sea lion subpopulations to be estimated. The models enable estimation of extinction probabilities for different subpopulations by utilising data on the: 1) spatial distribution of sea lion foraging effort (based on satellite tracking studies), 2) relationship between rates of bycatch and the probability of interacting with sea lions, and 3) population viability analyses. The models can accommodate new data as it comes to hand and are designed to be flexible and easily modified by fishery and conservation managers, enabling the exploration and rapid assessment of different management scenarios.

The decline of the endangered Macquarie Perch, Macquaria australasica, has been attributed partially to habitat modification, which can cause the mortality of fish in numerous ways including increased predation. Cotter Reservoir, the most downstream of three reservoirs that provide water to the Australian Capital Territory, has provided sufficient habitat to sustain a population of Macquarie Perch. However as drought conditions continue throughout Australia the expansion of Cotter Reservoir is imminent and existing habitat, specifically beds of emergent macrophytes, will be lost. Emergent macrophytes in Cotter Reservoir have been found to be an important part of the habitat for adult Macquarie Perch, providing protection from predators, in particular cormorants. This study will examine the behaviour of Macquarie Perch and cormorants using methods including radio-telemetry and observation. Experiments will be conducted to examine changes in habitat use by Macquarie Perch and the rate of predation by cormorants upon Macquarie Perch when emergent macrophytes aren’t available. Changes in rates of cormorant predation with the addition of artificial habitat will also be explored. As well as identifying the predator-prey dynamics of cormorants and Macquarie Perch it is hoped that this study will provide information that will ensure that cormorant predation and habitat loss do not combine to cause the demise of this population.