CCAMLR

In fishing season, 2008/09, at implementation of the program on Dissostichus spp. tagging aboard Korean longliner “22 INSUNG”, in the D’Urville Sea for the short, period of time the new data on migration of one individual D.mawsoni were obtained. Supposedly, the speed of migration was about 6 km per day.

The United Nations General Assembly (UNGA) Resolution 61/105 calls upon Regional Fisheries Management Organizations or Arrangements (RFMO/As) to take measures to prevent significant adverse impacts on vulnerable marine ecosystems (VMEs). In response to this CCAMLR has implemented a series of measures that limit the spatial extent, and require an assessment of potential impacts on VMEs, for those fisheries that interact with the seabed. In addition CCAMLR has and also codified an encounter with a VME during fishing operations and the resulting course of action to be taken by a vessel. In the first year of implementation 7 areas have been closed to fishing as a result of encounters with VMEs

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.

Three species of skates are commonly taken as incidental by-catch in the Patagonian toothfish longline and trawl fisheries, and the mackerel icefish trawl fishery on the Kerguelen Plateau, Bathyraja eatonii, B. irrasa and B. murrayi. The three skates are widely distributed across the Kerguelen Plateau, showing different spatial distributions, linked mainly with depth. In the Australian EEZ, B. eatonii and B. irrasa are most abundant to the north and northwest of Heard Island out to the edge of the EEZ, and down to depths of 1100m and 1500m respectively. B. irrasa occurs much deeper, down to 2300m in the HIMI region. The smallest species, B. murrayi, occurs only in the shallower waters down to 700m, and are most abundant close to Heard Island to the north and northeast. The catch rates of skates from the trawl fisheries at HIMI are low and do not show any evidence of depletion in the main fishing grounds at this stage. The marine reserves and the conservation measures employed by CCAMLR in the HIMI fishery appear to provide effective protection for the skates at least in the trawl fisheries. This study provides the first review of skate by-catch across both the HIMI and Kerguelen fisheries. We recommend ongoing monitoring of species specific bycatch levels, and further research to determine the life history parameters of these species, particularly for B. irrasa which is taken both in the trawl and the longline fisheries.

Bottom fisheries are now to ‘avoid significant adverse impacts on vulnerable marine ecosystems’ in order to maintain the ecological structure and function of, particularly, deep sea benthic habitats. Noting the paucity of data on the ecology of these habitats, this paper further develops a practical approach to develop and evaluate fishing strategies aimed at achieving this objective i.e. what is the most cost-effective way that fishers might be able to collectively enact this resolution? The UNGA requirement can be translated into a simple operational objective: Maintain the quality of habitats above the level that can naturally restore the original structure and function within 20 years. It does not require habitats to be categorised as “vulnerable marine ecosystems” or “invulnerable marine ecosystems”, a categorisation fraught with difficulty. Instead, it means that habitats for which this would not easily be met would be more vulnerable than those for which the objective might be met most often. The paper describes how the simulation model, Patch, has been updated according to the recommendations of WG-SAM, WG-EMM and WS-VME. The manual is included as an attachment. Patch represents key properties of the benthic system, including patch heterogeneity, decay, recovery and connectivity between areas. The model has been developed for use by CCAMLR to evaluate, using computer simulations, proposed within-season and post-season assessment and management strategies. Most importantly, the model enables uncertainties to be captured in a straight-forward manner to assist CCAMLR in maintaining its precautionary approach in managing Antarctic fisheries. The model is ready for use by WG-FSA this year to begin evaluating management strategies to conserve VMEs.

We provide an update of the Bayesian sex and age structured population stock assessment model for Antarctic toothfish (Dissostichus mawsoni) in the SSRU 88.2E, using revised catch, catch-at-age and tag-recapture data from New Zealand vessels and for selected trips. The New Zealand vessels model resulted in a higher estimate of initial biomass than the same model for 2006, but the estimated initial biomass was very imprecise. The selected trips data set resulted in a more precise estimate of initial biomass, although there was some conflict in the likelihoods of the tag recapture observations from different years. The use of the selected trips with the revised maturity ogive resulted in a greater similarity between the yields resulting from an assumption that the future fishing selectivity was equal to the current fishing selectivity and the assumption that future fishing selectivity was equal to the maturity ogive. Model fits to the data were adequate, with the tag-release and recapture data providing the most information on stock size, although there were conflicts between information in the recapture data from different years. Monte-Carlo Markov Chain (MCMC) diagnostics suggested no evidence of non-convergence in any of the models. The selected trips with the revised maturity ogive MCMC estimates of initial (equilibrium) spawning stock abundance (B0) were uncertain, with the median B0 estimated as 7 540 t (95% credible intervals 5 870–10 020 t), and current (B2009) biomass estimated as 80.7% B0 (95% C.I.s 75.34–85.5%). Estimated yields from this model were 361 t, assuming future fishing selectivity equal to the current fishing selectivity.

We provide an update of the Bayesian sex and age structured population stock assessment model for Antarctic toothfish (Dissostichus mawsoni) in the Ross Sea (Subareas 88.1 and SSRUs 88.2A–B), using revised catch, catch-at-age, and tag-recapture data for the 2008–2009 season. The reference model using the selected trips tag data and the revised maturity ogive gave a similar, but slightly lower, estimate of initial biomass to that from the 2007 base case. Two sensitivity models were run; one updated the 2007 base case assessment using New Zealand tag data only with the 2007 maturity ogive whilst the second use the selected trips data set with the 2007 maturity ogive. Overall, model fits to the data were adequate, and, as in previous assessments, the tag-release and recapture data provided the most information on stock size. Monte-Carlo Markov Chain (MCMC) diagnostics suggested little evidence of non-convergence in the key biomass parameters, although there was some evidence of non-convergence in the annual shift parameters for the shelf fishery. MCMC estimates of initial (equilibrium) spawning stock abundance (B0) for the 2009 reference model were estimated as 62 080 t (95% C.I.s 56 020–70 090 t), and current (B2007) biomass was estimated as 79.9% B0 (77.7–82.2%). Estimated yields for the reference case, using the CCAMLR decision rules, were 2850 t.