CCAMLR

Data on the main population of black petrel (Procellaria parkinsoni), which breeds on Great Barrier Island, were analysed. Three types of data were available. The most useful was abundance data, from which it was possible to infer that the population was probably increasing at a rate between 1.2% and 3.1% per year. Mark-recapture data were useful in estimating demographic parameters, like survival and breeding success, but contained little information on population growth rates. Fishery bycatch data from observers were too sparse and imprecise to be useful. The fact that the population is probably increasing shows that there is no evidence that fisheries currently pose a risk to this population. However, this does not imply that there is clear evidence that fisheries do not pose a risk to this population. The mean age of first breeding for black petrel is estimated to be 6.7 y. Before this, new adults spend an average of 1.2 y in the colony as pre-breeders, with only 3% skipping the pre-breeder phase. Of birds that appear in the study area as pre-breeders and survive to breed, only 68% do so in the study area. Once birds start breeding, their annual survival rate is 0.89, 80% breed each year, and of those, 77% are successful (i.e., produce a fledgling). Survival rates before the pre-breeder stage are not well determined because we can’t distinguish mortality from emigration (birds that breed in an area away from where they were hatched). Two recommendations for further monitoring of this population are: periodic repeats of the transect based abundance estimation last done in 2005 (to determine whether the population is increasing or declining); and the use of data loggers to improve our knowledge of the birds’ foraging range and thus help to identify fisheries that might be affecting this population. (New Zealand Aquatic Environment and Biodiversity Report, 51 (2010), ISSN 1176-9440)

Software is presented for the automated production of standardised image plots of spatially referenced data. While developed to satisfy the specific requirements of WG-FSA, the routines have been developed to be as generic as possible and may be useful for displaying a wide range of data. This software is submitted to be appraised by WG-SAM in the hope it may prove a useful tool within CCAMLR Working Groups for the display of spatially referenced data.

We report on progress towards developing a Minimum Realistic Model for investigating trophic relationships between Antarctic toothfish (Dissostichus mawsoni) and four groups of demersal fish in the Ross Sea, Antarctica. These demersal fish are known to form a part (in some cases a substantial part) of the diet of Antarctic toothfish of a size commonly taken by the Ross Sea fishery and are also taken as bycatch by the fishery: (1) macrourids (especially Whitson’s grenadier, Macrourus whitsoni); (2) icefish (especially Chionobathyscus dewitti); (3) deep sea cods (especially violet cod, Antimora rostrata); and (4) eel (moray) cods (Muraenolepsis spp.). Changes to the abundance of Antarctic toothfish due to fishing could affect these prey groups and the trophic relationship between these groups and toothfish. A Minimum Realistic Model is the most appropriate modeling approach to investigate what changes in the abundances of these four demersal fish prey/bycatch groups in the Ross Sea are possible, and what changes in the trophic relationships between Antarctic toothfish and these prey groups may occur. Feedback on the model is sought. Work on this model will continue through 2010 and 2011 and will be presented to CCAMLR in due course.

In 2008-2009 New Zealand developed an impact assessment framework to estimate the likely impacts of bottom longline fishing on vulnerable benthic invertebrate taxa, termed Vulnerable Marine Ecosystems (VMEs), consistent with the requirements of Conservation Measure 22-06 (Bottom fishing in the Convention area). The impact assessment framework was subsequently endorsed within CCAMLR for routine application by Members submitting notifications of their intent to participate in new or exploratory fisheries using bottom fishing gear (SC-CAMLR XXVIII, paragraph 4.247 v–vii), and was applied to estimate the cumulative historical bottom fishing footprint of all fisheries in the CCAMLR area. The Scientific Committee called for additional work to address remaining uncertainties about the nature and extent of bottom fishing impacts on potential VMEs (SC-CAMLR-XXVIII paragraph 4.251). The purpose of this paper is: i) to estimate impacts on VMEs per unit effort using a simulation approach with explicit incorporation of uncertainties in the input assumptions; ii) to examine the application of the impact assessment framework at different spatial scales, and implications for the validity of the underlying structural assumptions of the assessment framework; and iii) to express impact estimates in a spatially explicit manner with reference to areas of distinct environmental characteristics arising from a benthic bioregionalisation of the Ross Sea region (Sharp et al. 2010). We conclude that bottom fishing impacts on VME taxa in the Ross Sea are low.

An important management objective for CCAMLR in the high seas region of the Antarctic is to develop appropriate methods of monitoring and managing impacts of bottom fisheries on vulnerable marine ecosystems (VMEs). We describe a spatially explicit production model that can be used to investigate a range of simple scenarios for simulating the effect and management of benthic impacts from longline fishing effort. Simulations were carried out under a range of productivity assumptions, impact, and spatial scale, with and without management by areal closures. Further, the management action simulated considered a range of areal closure radii and bycatch trigger thresholds. We conclude that spatially explicit production models can provide a useful tool for the investigation of impacts of fishing effort on benthic organisms. They have the advantage that they are relatively simple to construct, run, and interpret. In general, the results of the simulations suggested that management action of areal closures in the Ross Sea region are likely to result in an improved outcome over scenarios where there was no management action, but that the size of effects under the plausible models was often very small. We also note that further work on these simulations are required — including investigating how changes in the distribution of future fishing may result in alternative impacts or how different assumptions of the underlying distributions of benthic organisms may influence the results. However, as the size of these impacts in the scenarios tested were small, we recommend that research be focused, at least in the short term, to provide observational or experimental data necessary to constrain important model parameters, to reduce uncertainty and provide more plausible scenarios.

Bathymetric data are currently used inter alia to define management boundaries, implement conservation measures, allocate catch among areas, estimate spatial impacts due to fishing, and inform ecosystem-based management through bioregionalisation. Several data sources for bathymetric data exist, and these sources improve with time through additional data collection and improved analytical methods. We developed an algorithm to summarize bathymetric point data (x,y,z) for the Ross Sea region to provide a transparent and citable method to derive standard summary statistics for use by CCAMLR. This is especially important because of the multinational use of such data. The method is applicable to the entire Southern Ocean, but is currently applied only to the Ross Sea region. We have obtained publically available bathymetric data, created a spatial database, and have developed scripts for defining polygons of user-specified bathymetric areas, calculating the areas of those polygons, and displaying them as contour maps. As data sources improve, this process can update the summary statistics as needed in a comparable and transparent manner.

Sources of variability of krill mean length and fish bycatch number was investigated to explore proper allocation of scientific observers on Japanese krill fishing vessels using the data from 1995 to 2008. Based on the multistage sampling theory, we derived the equation of variance in four stage cluster sampling units (i.e., vessel, year, subarea, and haul), and examined changes in the coefficients of variation (CV) caused by the shifts in coverage at different sampling stages. Vessel coverage had the largest impacts, and year coverage had moderate impacts on CV for both mean krill length and fish bycatch. The impacts of subarea and haul coverage were different between krill length and fish bycatch. Fish bycatch required moderate coverage for haul but low improvement were made by increasing subarea coverage, whereas krill length allowed very low haul coverage but preferred higher subarea coverage. To determine the proper level of observer coverage, the purpose and cost of observer monitoring should be discussed.

Distribution, relationship between sizes and depths, sex ratio, size composition and maturity condition for Dissostichus eleginoides and D. mawsoni were investigated on Banzare Bank, using the biological data sampled by a Japanese commercial fishing vessel during austral summer from 2006/07 to 2008/09 fishing season. D. eleginoides was mainly caught in the shallower bank <1000 m, while D. mawsoni was mainly caught in the deeper slope >1500 m. The separation of the two species by depths may be related to the physical intolerance to the cooler temperature by the lack of antifreeze for the former species. The mean total length (TL) of females was significantly larger than that of males for both species. The proportion of males to the total adults decreased significantly with the depths with gradual slope for both species. Male D. mawsoni showed a significant correlation between depth and the TL with gradual slope. The size structure varied among the fishing seasons and showed the polymodal distribution in D. eleginoids, while the size structure was very similar among fishing seasons and showed the unimodal distribution in D. mawsoni. D. eleginoides showed resting stage in sexual maturity, while D. mawsoni was in running ripe condition. In both species, small fish contributed low proportion in abundance, which suggest that substantial recruitment does not take place on Banzare Bank and the population may consist primarily of adults migrating from other area

In order to clarify the stock status and biological characteristics of Dissostichus spp. In Division 58.4.4 a & b, we submit this research plan for toothfish in the Division by Shinsei Maru No. 3 to be conducted in April-June 2011. This is the second year of the survey of the 3-5 years consecutive research focusing on tagging program, recommended by WG-SAM-09 in this Division, following the first survey conducted in 2009/10 season, when total sample size for Dissostichus spp. Was allowed as 60,000 kg. The research hauls are allocated on 10-minute latitude x 20-minute longitude grid points, taking into account the need to deploy research hauls and tagging releases evenly throughout the survey area in the same manner as 2009/10 survey. A Trot line system will be employed for all hauls. To apply the mark-and-recapture studies, sufficient tagging rate of 5 fish / ton will be conducted in the same manner as the 2009/10 survey. We calculated the two values (78 and 114 tonnes) of total allowable sample size for the 2010/11 survey, taking into account the need for completion of the survey and impact on the fish stock, and will take advices for the method of estimations in the WG-SAM-10 meeting.