CCAMLR

A non-hierarchical seabird identification key has been produced to improve the identification of seabirds that come into contact with or are seen in the vicinity of fishing operations in the Heard and McDonald Islands region. This paper provides the background and reasoning behind the development of this key.

This paper presents a framework to assess and quantify the likely cumulative impact on potential VMEs from bottom fishing activity. The approach has been designed to facilitate standardized application across gear types and areas to allow comparisons between fisheries employing different bottom impacting fishing methods. Details of the New Zealand preliminary assessment using this framework are available in document CCAMLR XXVII-26. This paper illustrates the utility of the standardized approach and provides a methodological template for possible wider adoption within CCAMLR or elsewhere. Specific examples from the New Zealand assessment are provided for illustrative purposes.

The New Zealand fishing company Sanford Limited has initiated a research project to assess the effectiveness of artificial bait as a means of reducing the incidental catch of Macrouridae (rattails) and other bycatch species in the toothfish autoline longline fishery. A company vessel carried out some initial experimental work in the western Ross Sea (CCAMLR Statistical Subarea 88.1) in 2007 to assess basic requirements such as ease of use, bait longevity on the hook, and catchability (defined here as a measure of a baited hook to attract and catch a given species of fish) of target and incidental species. This is a preliminary report based on subsequent trials carried out aboard the vessel San Aspiring operating in the waters of South Georgia and the South Sandwich Islands (CCAMLR Statistical Subareas 48.3 and 48.4) during early 2008. During the period 12 April and 14 May 2008 seventeen trial lines were set in both Subareas; a total of 137,000 experimental hooks. The evaluation was based on alternating sections (magazines or mags - there are approximately 1024 hooks per magazine on San Aspiring) of line with control mags baited with squid, the vessel’s preferred bait for toothfish and alternating mags using an artificial or reconstituted bait (Norbait 800C™). Results from Subarea 48.4 indicated that catches of both the target Patagonian toothfish and bycatch of Macrourus whitsoni were reduced using Norbait when compared to the conventionally used squid bait. The reduction in rattail catches however was proportionally much greater than that of the toothfish and points to a potentially useful means of limiting Macrourid bycatch. This is similar to results obtained by another Sanford vessel San Aotea II in the Ross Sea in early 2007. This was not the case in Subarea 48.3, the other area where trials were carried out. In this area although Norbait reduced the incidental bycatch of Macrourus, an overall virtually identical reduction in the target catch of Patagonian toothfish negated any benefit. These reductions effectively meant an increase in fishing effort and time to achieve the same target catch result. Other than the obvious geographical differences between the two trial Subareas there were differences in both the Macrourus species caught and the size of toothfish caught in each. These factors may individually or in combination provide some explanation for the observed dissimilarities. There are a large numbers of variables involved in such comparative trials making definitive analysis difficult and precluding clearly defensible results. In such cases the collection of large amounts of base data in all circumstances and environments is the only way of reducing uncertainty and understanding the variability. For this reason it is necessary to stress that these results are preliminary and further work is indicated. Although increased and continuing data collection is an ideal, it must be highlighted that there are both clear and concealed costs involved in undertaking such trials. Obvious expenses are incurred in the purchase and transport of the trial bait. There are however hidden costs incurred in the additional time on the grounds and additional gear deployed to catch the same amount of fish when the bait used is less effective than the current standard.

We examined a methodology for assessing potential risk of interactions between fisheries and species of special interest (seabirds and marine mammals) by applying a Productivity-Susceptibility Analysis to a data set of species distribution, biological information and fishing effort. This type of Level Two Ecological Risk Assessment (ERA) has been used across fishery management regimes to identify areas or species requiring additional management or monitoring. Our study indicated that the risk of species interactions is clustered with greatest likelihood in a few species, where there is particularly strong overlap between fishing effort and species ranges. We tested the sensitivity of the analysis to changes in weighting of distributional density, fishing data type (area or point data), and to adding a factor of population. We found the outcomes of the PSA analyses were robust to these effects. However, adult survival rates did influence the rankings, and were identified as a key parameter requiring careful estimation. Relative risk rankings within the longline, trawl, troll and set net fisheries examined indicated that Procellaria petrels, the coastal Hector’s dolphins (Cephalorhynchus spp.), giant petrels (Macronectes spp.), Pterodroma petrels, and some albatrosses carried the highest relative risk. For setnet fishing, dolphins and shags were also ranked relatively highly. We examined the small statistical areas where most risk across all species applied cumulatively. We identified areas where there is greatest potential for non-target take to be occurring and which are therefore candidate areas for intensified observer monitoring and mitigation of risks.

The aim of this paper is to review the recent management of the Ross Sea toothfish fishery (including the 3-year experiment), to identify key operational and research objectives for the fishery over the next 5–7 years in relation to Article II of the Convention, and to develop an operational framework to achieve those objectives. The paper focuses primarily on Antarctic toothfish, as catches of Patagonian toothfish are negligible, and covers Subareas 88.1 and 88.2. We begin by summarising the operational management and conduct of the fishery up to the 2004–05 fishing year (prior to the start of the 3-year experiment). This includes the reasons why the 3-year experiment was initiated and the key objectives of the experiment. We then go on to summarise the operational changes which formed the framework of the 3-year experiment, and to review the success and/or any problems associated with each of those changes. Next we identify key operational and research objectives for the fishery over the next 5–7 years in relation to Article II of the Convention. As part of this process we identify uncertainties in our current knowledge which need to be addressed to fulfil the requirements of Article II. These include, for example, uncertainty in the biological parameters and stock assessment of Antarctic toothfish, uncertainty in its ecological relationships with predators and prey, and uncertainty over other ecosystem effects of fishing. Finally, we provide recommendations on the development of an operational framework for the fishery.

Skates are an important bycatch of the toothfish fishery in the CCAMLR area and have been identified as priority taxa for which assessments of status are required (e.g., SC-CCAMLR XXIII 2004, paragraphs 4.172, 4.177 and 4.199). While Dunn et al. (2007) and Agnew et al. (2007) have developed preliminary assessment models for skates, they also highlighted that further information was required before a full assessment can be carried out. In 2007, WG-SAM recommended (CCAMLR XXVI WG-SAM paragraph 8.10) a review of data requirements and a “Year of the Skate” for 2008–09 whereby data collection effort on bycatch will be concentrated on skate species in that year in order to inform a full skate assessment. This paper discusses improvements to the fishery derived data that may be required to better inform an assessment of Ross Sea skates. We propose options for the appropriate collection of such data from the fishery and a revised skate tagging protocol. These changes were piloted in the 2007–08 season by a subset of vessels fishing in the Ross Sea. The results from the pilot study are useful to inform modifications to data collection systems that are required in 2008–09, for the “Year of the Skate”. Note that we do not consider other information requirements such as determining biological parameters.

Through generalised linear models, the gonadosomatic index of Antarctic toothfish in the Ross Sea region was shown to vary with latitude, length and month. Limitations of the scientific observers’ staging data were highlighted and GSI is recommended as a better indicator of maturity status in Antarctic toothfish. Reports of histological analyses of a small number of Antarctic toothfish showed vitellogenic fish with low GSI values, in some cases below 1%. In most studies there was little if any difference in the GSI values of fish at different maturity stages. However these studies were carried out on a limited number of fish, most of which were from the southern area, therefore not on obviously spawning fish. Histological analysis using a hindcasting assessment of 683 samples collected in December to February showed most fish on the shelf had not spawned that year, most fish in the north had spawned and the shelf contained a mixture of fish that had spawned or not, with length at 50% maturity of about 137cm. The equivalent GSI at 50% maturity was in the range of 1.1 to 1.4%. These results were used to estimate GSI thresholds for fish that had spawned in the previous season; which were set at 1% and 1.5% GSI, but are limited to only female fish in the sampled areas for December through February. Based on both histology and GSI data, most fish found in the northern areas, about a third of those found in the slope areas and very few of those found in the southern areas had spawned. As the GSI values of fish caught in the northern area were never very low, it is expected that all the fish in the northern areas spawn every year when in that area. If they were resting in the north it is expected residual GSI would be lower. Conversely, as the GSI values of fish caught in the south were very low, fish caught there are not expected to spawn in the current year, nor are they expected to have migrated back from the north; or their residual GSI would be higher, in the order of 1% or more. Therefore any movement would have to be between the north and the slope areas, with only a proportion of fish coming back to the slope since only a third there are mature. Any other movements would have to be outside of the fishing season, for example a yearly northern migration during spawning season only. Lengths at 50% maturity of Antarctic toothfish were calculated for each SSRU or area in the Ross Sea region; they varied from about from 89 to 150cm for females and 36 to 184 cm for males, from north to south respectively. Length at 50% maturity was also calculated for female fish from the slope, which was similar to the value calculated from GSI of 137cm. Uncertainty in the oocyte development cycle may create biases in different histological assessment methods which may influence estimates of length at maturity or GSI thresholds. Length distributions are also known to be spatially heterogeneous. A population-wide length at 50% maturity can therefore not be determined without the help of a spatially-explicit population model and any length at maturity value should be treated with caution. Gonadosomatic index has shown promise as a potential index of Antarctic toothfish maturity. However, further work is recommended in order to improve the current knowledge of toothfish maturity...continued

This paper documents recent and ongoing developments in New Zealand’s Exclusive Economic Zone that are relevant to the work of WG-IMAF. These developments include refinement of the requirement of fishing practices to reduce seabird bycatch by surface longline vessels and the introduction of regulations to reduce seabird bycatch by bottom longline vessels. The bycatch of seabirds by fisheries within New Zealand’s EEZ in recent years that either breed or forage within the CCAMLR convention area (Convention seabirds) is detailed. This paper includes a tabulation of observed captures by species and bycatch estimations by fishery for all seabirds. This paper also contains description of the recent and ongoing seabird mitigation trials that are underway in New Zealand. These include trawl offal management techniques, such as batching and mincing, and the blue dyed bait trial for surface longline fishing. We also discuss a new version of the Productivity-Susceptibility Assessment technique for risk assessment and its potential for use in the CCAMLR context.

1. So far a total of 929 D. eleginoides have been tagged and released at Subarea 48.4 and 25 tagged fish have been recaptured, including 23 during the latest season. 2. A preliminary assessment of D. eleginoides stock size in the Northern Area of 48.4 estimates a vulnerable biomass of between 1,000 to 2,000 tonnes. 3. The UK proposes to continue the mark-recapture experiment in Subarea 48.4 in the 2008/09 fishing season so as to allow for a full assessment of D. eleginoides stock size in the Northern in 2009. 4. Additionally, the UK proposes to commence a mark-recapture experiment in the southern area of Subarea 48.4. This has the aims of providing the data required for assessments of the population structure, size, movement and growth of both Dissostichus eleginoides and Dissostichus mawsoni in the southern area of 48.4. 5. A catch limit of 75 tonnes is proposed for D. eleginoides the northern area, where D. mawsoni will remain a bycatch species. A combined catch limit of 75 tonnes is proposed for D. eleginoides and D. mawsoni in the southern area. 6. It is proposed that catch limits are introduced for bycatch species in the Northern Area of 48.4, set at 16% Macrourus spp. and 5% Rajid spp of the catch limit for Dissostichus species. In the Southern Area, catches taken at these proportions would trigger a move-on rule. 7. The UK has submitted a complementary proposal to IMAF to amend CM 24-02, to bring the mitigation requirements for 48.4 into line with the IMAF risk assessment, such that daytime setting would be permitted if bottle tests are undertaken, and the fishing season is extended to run from 1 December to 30 November.

The provisions for fishing season and mitigation measures in Conservation Measure 24-02 (2005) regulating fishing in Subarea 48.4 do not currently conform to the IMAF Risk Assessment advice given in CCAMLR-XXIV/BG/26. The UK proposes text that should be added to CM 24-02 to bring the measure into line with the Risk Assessment, which would allow fishing outside season April – September if it is conducted in accordance with CM 24-02. A small change, to recognise 48.4, is required to the first paragraph of CM 24-02.