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

Stock assessment of ruby snapper (Etelis carbunculus)

Cass Hunter

CSIRO Marine Research, CLEVELAND, AUSTRALIA

THEME: ASFB

The effects of fishing the ruby snapper (Etelis carbunculus) resource in the Western Deepwater Trawl Fishery (WDWTF) was evaluated through a quantitative stock assessment. Intense fishing is known to cause overfishing of ruby snapper due to the aggregating behaviour of the species and preference for restricted continental shelf habitats. This vulnerability to heavy fishing was thought to have caused a fall in ruby snapper catch rates. The perceived state of the ruby snapper resource raised concerns over the status of the stock. A robust estimate of ruby snapper stock size could not be established using catch-per-unit-effort data in a biomass-dynamic model; because the lack of contrasts in the data prevented reliable population parameters being estimated. Results from a yield-per-recruit analysis revealed that the optimal size to harvest ruby snapper was 63 cm. Stochastic modelling assessed the uncertainty associated with this size limit. The reliability and accuracy of the management outputs from this stock assessment was constrained by poor data quality and quantity. Significant progress was however made in regards to improving data collection for management purposes. Implementing these recommendations is vital in ensuring the future sustainability of the WDWTF ruby snapper resource.