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

Impoundment Stocking Strategies for Four Australian Native Species: Does Size Matter?

Michael Hutchison and Thomas Gallagher

Queensland Department of Primary Industries, DECEPTION BAY, AUSTRALIA

THEME: ASFB

Stocking of impoundments with native fish for recreational fishing enhancement is a beneficial but expensive socio-economic activity. Therefore it is important to optimise stocking strategies to avoid wasting money and effort. Through use of micro-tagging technology we were able to compare the relative stocking success of three size classes (20-30mm, 35-45 mm and 50-65 mm) of Australian bass, barramundi, golden perch and silver perch over three years. We also compared three release strategies: deep water release, shallow water release and release into artificial cover. Micro-tagged fish were released annually into 35ha -200 ha impoundments located in sub-tropical Queensland. Results indicated that for all species the 50-65 mm size class had the highest relative survival rate although recapture rates varied between years and dams. Variability can in part be attributed to the presence of predatory species. In general when the purchase price of fingerlings is taken into consideration the 50-65 mm size class was the most cost effective to stock. However, if there are few predators present then 35-45 mm and even 20-30mm fish can become the most cost effective to stock. There was variation in the relative success of the different release strategies between dams and years. This was mainly attributed to chance distribution of predators at time of release. Shallow water releases appear suitable for all species and it is recommended fish be released in at least three large batches into different locations around the dam to spread the risk of predation.