ASFB Home > The effects of spatial and temporal factors on the abundance of seven key finfish species along south-western Australia.

Ichthyoplankton from the Southern North West Shelf of Australia

Alison Sampey, Mark Meekan and Dave McKinnon

James Cook University, TOWNSVILLE, AUSTRALIA

THEME: ASFB

Temporal variation in the environmental conditions experienced by fish larvae will influence survival and contribute to recruitment variation. To investigate within and between year levels of variability in the distribution, abundance and survival of fish larvae, ichthyoplankton were collected in bongo nets at 2 sites located on the continental shelf near North West Cape (21º49'S, 114º14'E), between October and February of 1997/98 and 1998/99. The first summer was characterised by ENSO driven upwelling and high primary productivity, by comparison, in the second year water temperatures were warmer, and primary production was lower. Preliminary examination of catches, showed that in 1997/98 just 4 families (gobiids, carangids, apogonids and myctophids) accounted for 48% of the 1406 individuals of post-flexion larvae identified. Temporal differences were detected when considering the complete larval fish assemblages, although spatial differences were evident when individual taxa were considered. In 1997/98, seasonal differences were significant, primarily due to the presence of oceanic taxa (eg myctophids and gonostomatids) in the spring (October) and reef-associated taxa (eg gobiids, carangids and apogonids) in the summer (December and February). This data is compared with catches from 1998/99. These distribution patterns are discussed in relation to the spawning patterns of adult fishes, and physical and oceanographic features.