DEVELOPMENT OF RECOVERY PLANS FOR DEPLETED TOOTHFISH STOCKS IN THE INDIAN OCEAN SECTOR OF THE SOUTHERN OCEAN

Stocks of Dissostichus mawsoni on BANZARE Bank (Division 58.4.3b) and D. eleginoides on Ob and Lena Banks (Divisions 58.4.4a and 58.4.4b) have been subjected to unsustainable levels of IUU and commercial fishing and it is likely that they are depleted below the threshold for CCAMLR fisheries. An updated assessment of that status the stock at BANZARE Bank using data from the recent seasons along with the estimated time series of historical catches are used to provide estimates of B0 for this Division. For a range of scenarios, the Generalised Yield Model is then used to assess foregone yields and to estimate (i) the probability of being depleted below 0.2B0 and (ii) the time to recovery to 0.5 B0. These scenarios indicate that this stock is likely to be depleted and fishing should cease. Recovery trajectories indicate it is likely that it will be at least 5 years before it is sufficiently low risk to survey this stock to determine if recovery is occurring. We propose surveys to be undertaken after 5 years and then two years later. The surveys should have only low catches in order to not impede recovery. The surveys should involve a mark-recapture program, estimation of catch rates in the main grounds for comparison with historical catch rates and otolith collection to estimate age structure and recruitment variability. After the two surveys, data should be analysed to determine how fast the stock is recovering and what the future monitoring and recovery strategy should be to allow the stock to achieve the target status, when the fishery could be re-opened. We recommend this strategy be used as a monitoring and recovery strategy for Patagonian toothfish on Ob and Lena Banks.