Species identification of Australia’s most significant octopus fishery – the Western Australian Common Octopus
Verification program for the use of 'Rapid Test Kits' to safeguard and grow the WA Shellfish Industry
Where did the Snapper go? Determining factors influencing the recovery of Snapper stocks on the west coast of Australia
Assessment of the Inflamark method as a sensitive and cost-effective measure of oxidative stress in cultured fish
Developing novel remote camera approaches to assess and monitor the population status of Australian sea lions
The Australian sea lion (Neophoca cinerea) is the only endemic species of Australian pinniped and is listed as Vulnerable under the EPBC Act due to historical reduction in numbers, declining population trends, limited biological productivity and continued bycatch in various fisheries. Measures to mitigate sea lion mortality in the Commonwealth's Southern and Eastern Scalefish and Shark Fishery include extensive gillnet fishing closures that have led to significant displacement of fishing effort. Despite the measures to protect South Australian sea lion colonies, pup production has been estimated to have declined at most South Australian colonies and overall by 2.9% per year or 4.4% per breeding cycle between 2004-2008 and 2014-2015 (Goldsworthy et al., 2015).
Gillnet exclusion areas have also been proposed in the Western Australian Demersal Gillnet and Demersal Longline Fisheries, however these have not yet been implemented, in part due to uncertainties in the current status of most Western Australian sea lion colonies and risk of unintended consequences from displaced fishing effort. Despite the high level of conservation concern for this species and the severity of fishery management measures aimed at reducing their bycatch mortality, abundance has not been estimated for most WA colonies since the early-1990s (Gales 1993). Contemporary assessments of colony status are therefore required to identify the WA colonies that are most at risk from depletion (either through fisheries bycatch or other natural or anthropogenic processes) and guide effective conservation decisions.
Historically, monitoring has involved a 'boots-on-the-ground' approach to count the numbers of pups being born. However, this approach is expensive, logistically difficult, hazardous and entirely dependent on accurate estimation of the timing of colony-specific pupping seasons. It is therefore proposed to evaluate the feasibility and cost-effectiveness of remote camera methods to collect alternative sea lion abundance estimates.
Final report
Determining variation in catchability of Western Rock Lobsters to standardise important abundance indices used for stock assessment
An outcome of a recent review of the WRL fishery (FRDC 2015-236) was to conduct a sensitivity analysis on a range of parameters utilised by the Western Rock Lobster (WRL) stock assessment model. This analysis highlighted that stock projections and MEY analysis are both sensitive to lobster assumptions associated with the catchability of lobsters during IBSS surveys. Recent stock estimates consider the population of the western rock lobster to be at record high levels. Therefore, even relatively minor differences in lobster catchability can have profound effects due to the multiplicative effect of increased stock size.
With the recent marine heatwave off the WA coast producing record-high, projected increases in water temperature, and the substantial increased population abundance and size composition, there are likely to have been substantial changes in the catchability of lobsters during the IBSS, which may be impacting on the stock projections being produced for the fishery.
The continued reliance of the stock assessment on independent indices while commercial fishing patterns (fishery dependent indices) become more consistent, requires that the variation in lobster catchability during these surveys is accounted for. If industry seek to increase WRL quotas in future seasons to take full advantage of the recent free trade agreement with China, it will be beneficial if the stock assessment is based on reliable indices of abundance to determine the appropriate TAC. Setting the quotas too low would affect industry’s profitability, while setting them too high would reduce fishers’ catch rates, affect the spawning stock and risk the sustainability of the fishery. Accounting for the biases impacting on abundance indices use to drive the stock assessment model (thus improving the accuracy of the model) will allow the fishery to maintain fishing at an appropriate level that achieves its harvest strategy target of maximising its economic yield and maintains a healthy spawning stock.