CCAMLR

We describe the process used in the fisheries management system of the Convention for the Conservation of Antarctic Marine Living Resources (CCAMLR) to minimise seabird bycatch, and the risk assessment methodology developed to assist this. We examine the progress of several Regional Fishery Management Organisations in taking steps to address seabird bycatch. CCAMLR has the most advanced system of management among the RFMOS covered in this review, and has made the most demonstrable progress in reducing seabird bycatch levels in its longline fisheries. A combination of proven mitigation measures, extensive monitoring by independent observers, annual expert review of seabird bycatch rates and evolving fishery and mitigation practices have been instrumental in reducing seabird bycatch in CCAMLR fisheries.

The most abundant icefish species observed in catches off the northern tip of the Antarctic Peninsula in the last 25 - 30 years has been the spiny icefish Chaenodraco wilsoni Regan 1914. C. wilsoni has been exploited on a commercial scale from the late 1970’s to the end of the 1980’s off Joinville – D’Urville Islands (CCAMLR Statistical Subarea 48.1) and in the Cosmonauts and Cooperation Seas and Prydz Bay in the Indian Ocean sector (CCAMLR Statistical Division 58.4.2). This paper presents new information on biological features and life history characteristics of C. wilsoni, based on research survey collections along the northern Antarctic Peninsula in 2006 and 2007 and samples taken in the commercial fishery in 1987. Length frequency compositions from the research surveys demonstrated that fish 21 – 34 cm long predominated in the catches. Sexual maturity is attained at 24 – 25 cm. Absolute fecundity and relative fecundity is low (1000 – 2500 eggs; 6 – 12 eggs). Oocyte diameter varied from 4.3 to 4.8 mm very close to spawning. Spawning at the tip of the Antarctic Peninsula is likely to occur in October-November. Remotely Operated Vehicle deployments in the northern Weddell Sea demonstrated that C. wilsoni exhibit parental nest guarding where males protect the eggs. The incubation period is likely to be 8 months long. Fish feed primarily on Antarctic krill (Euphausia superba) in the Antarctic Peninsula region and in the Cosmonauts and Cooperation Seas while fish take ice krill (E. crystallorophias), Pleuragramma antarcticum and myctophids to some extent in other areas. Age determination still awaits validation. Preliminary ageing attempts suggested a maximum age of about 8 – 10 years.

The rocks from stomachs of Dissostichus mawsoni were used as a source of geological information about sea bottom. Authors suggest toothfish picks up stones from the bottom randomly, and these stones may be used for geological description of the closed areas of Antarctic shelf and slope. In this respect, Dissostichus mawsoni may be considered as a «dredge» with a wide area of sampling. Preliminary analyses allow qualitative estimation of geological structure of Antarctic shelf and continental slope in different areas.

This is a preliminary report of the results of the 11th UK South Georgia groundfish survey, the first to be conducted during the austral winter since 1997. Preliminary biomass estimates are provided for C. gunnari whilst new information on the winter distribution and ecology of the demersal fish fauna at South Georgia is provided.

Analysis of recent commercial catch, research survey and larval data for mackerel icefish (Champsocephalus gunnari) recorded from CCAMLR Subarea 48.3 coupled with historical information indicates that they spawn inshore close to the bays and over the shelf to the northeast. There is also evidence that spawning is protracted and occurs from January through to July. The majority of commercial fishing activities for this species take place to the northwest of South Georgia over 12 nautical miles from the coast and do not overlap with important spawning areas. Therefore the current conservation measure restricting the total allowable catch during the assumed spawning period from March-May is unlikely to protect spawning aggregations of C. gunnari but could, inadvertently, increase the risk of brooding seabirds being caught as by-catch.

This document summarises the suggestions made by WG-EMM to address the requests made by the Scientific Committee in relation to Scientific Observer Manual. These are establishment and replacement of protocol for fish-larvae by-catch observation, review of priorities for scientific observation of krill fishery, and other minor revisions on the e-forms. This document also contains examples of the revisions made to the forms and is presented to the Working Group on Fish Stock Assessment for comment.

This paper further develops an integrated assessment for Patagonian toothfish in Division 58.5.2. It updates the model used at WG-FSA in 2006 using data from the 2007 season as well as 2006 data not available for WG-FSA in 2006. It also includes the following refinements: (i) estimation of the coefficient of variation (CV) for length given age, (ii) use of non-informative priors for year class strength parameters, (iii) separate selectivity parameters used for the pre-2006 compared to the 2006-2007 fishing seasons for the main trawl ground, (iv) separate selectivity parameters for the late (within-year) season compared to the combined early (within-year) seasons for the main trawl ground, and (v) the use of an improved method of determining effective sample size for commercial catch-at-length data. The estimated long-term yield was 2500 tonnes with depletion probability of 0.081 and escapement probability of 0.505. As expected, the assessment was sensitive to the inclusion of different datasets and to the choices of parameters used in both the stock assessment and projections. It is concluded that until the difficulties with the use of mark-recapture data are resolved, recruitment surveys provide the best means of establishing current stock status as an absolute index of abundance.

Fish samples collected through an overall period of 24 years at Potter Cove after the impact of the fishery in the area in 1978-80, allowed the comparison of the variations in mean annual lengths and density distributions of the commercially exploited species N. rossi and G. gibberrifrons with the ecologically similar but unexploited N. coriiceps. The sharp decline in the abundance of N. rossii reported for the period 1983 - 1991/2 is consistent with the increase in mean size observed between 1983 and 1986/7 and the duration of the inshore phase of the species, which is known to last for 6-7 years. In the following years, until 1991/92, the decreasing abundance is consistent with the entrance of low strength cohorts with the consequent reduction in mean size. The above interpretation is supported by the length distributions observed between 1982/83 and 1985/86, where the modal age changes from 2/3 to 6/7 years. After 1991/92 the densities, mean sizes and abundances do not depend on a single forcing event but on several interacting factors. The length data of G. gibberifrons, available from 1986, show a decrease until 1991/92, exhibiting a similar pattern to that of N. rossii. After a period of relative stability in mean sizes (1992-1994) a sharp increase is associated with a continuous decline in relative abundance suggesting that it is due to increasingly low recruitments. The length frequency distributions of N. coriiceps through the whole studied period do not show any definite change in modal size, nor a pattern in mean lengths as is the case with N. rossii and G. gibberifrons.

We analyzed data collected during 2005 seabird mitigation experiments on integrated weight longlines (IW) in a demersal longline fishery for effects on skate bycatch. Trials took place on two vessels targeting Pacific cod (Gadus macrocephalus) over a five-month period in the Bering Sea, Alaska, USA. The skate catch rate was 11% lower on the IW gear compared to unweighted gear. Location, month and depth were also significant predictors of skate catch rates. While results indicate IW shows potential to reduce skate catch rates, further evaluation and analysis by individual species should be performed in specific regions where skate bycatch is a problem.