CCAMLR

In April 2008 the UK undertook a bottom trawl survey of CCAMLR Sub-Area 48.3 on the FV Sil, with 70 bottom trawls undertaken giving good geographic coverage. Using 10 strata and the updated sea-floor areas and adjusting this for the low headline height of the UK trawl (see CCAMLR WG-FSA (2003), the biomass of mackerel icefish was estimated to be 80,426 tonnes, with a lower 1-sided 95% CI of 30,050. Catch-weighted length frequencies indicated that icefish population was dominated by 2+ and 3+ fish, with differences in the size between Shag Rocks and South Georgia and with few small fish in the NW South Georgia area. A preliminary short-term projection of the mackerel icefish stock was run using standard CCAMLR parameters in the GYM. Two scenarios were tested, both assumed that all the 2007/08 catch that remained after the survey (1709 tonnnes) will be taken. Scenario 1, which included the 1+ fish produced yield of 3445 tonnes in Year 1 (2008/09) and 2318 tonnes in Year 2 (2009/10). In Scenario 2, in which the 1+ fish were excluded and biomass adjusted accordingly, yields were 3372 and 2248 tonnes in Years 1 & 2 respectively. The Patagonian toothfish population was dominated by the same cohort that has been detected by surveys since 2003, with no evidence of new recruitment since. Biomass estimates and length frequencies are reported for other non-target species. Conducing the survey in April was successful. The icefish appeared to be dispersed, which is amenable to a random trawl survey. There was evidence that the September 2007 survey under sampled the 2+ fish, meaning that September is not an ideal time for a survey.

Results of the survey of entanglements of Antarctic fur seals Arctocephalus gazella at Bird Island, South Georgia for the 18th consecutive winter (April to October 2007) and 20th consecutive summer (November 2007 to March 2008) are reported here. During the reporting period of 1 April 2007 to 31 March 2008 a total of 36 entangled seals were observed. Sixteen and 20 entanglements were observed in the winter and summer periods respectively. Entanglements classed as Severe or Very Severe accounted for 25% of winter and 10% of summer entanglements. During winter, synthetic string/longline material was the most commonly found item forming neck collars (44%), whereas during summer the largest proportion of entanglements were in sections of fishing net (40%). Packing bands were the second most abundant entangling material in both summer (38%) and winter (25%). The majority of entanglements (78%) involved juveniles (including pups and sub-adults), comprising 88% in winter and 65% in summer. Data for the winter period showed a decrease in the number of entanglements compared to the high levels during the previous season, but levels were still above the long term winter median (1990-2006). Data for the summer period showed a small rise in the number of entanglements compared with the previous season, but levels were slightly below the long term summer median (1989-2007).

This report details the twelfth annual survey of the incidence of entanglements of Antarctic fur seals Arctocephalus gazella and eighteenth beach survey of man-made debris at Signy Island, South Orkney Islands. Data are reported for the period 14 November 2007 to 13 March 2008. Three seals were observed with neck collars formed from fisheries related debris. Beach surveys recovered a total of 56 items weighing 11 kg, representing an increase from 2006/07 of 11% (by number) and 33% (by mass). There was a decrease in the number of plastic packaging bands with only two found in the current season (both of which had been cut open), marking a break in the otherwise continued rise in packaging bands observed. Styrofoam and other plastic waste was predominant, making up 64% of all items recorded. Fishing related debris contributed 11% of all items (9% rope and 2% trawl net webbing). These results show that the longevity of plastics and other materials with a high resistance to degradation in the marine environment remains a problem. The need for continued monitoring to ensure that vessels are aware of, and comply with, regulations prohibiting the disposal of debris at sea is paramount.

This report describes and quantifies occurrences of fishing gear, marine debris and hydrocarbons associated with seabirds at Bird Island, South Georgia for the period 1 April 2007 to 31 March 2008. It is the fifteenth such annual report. As in previous years, the majority of items (84%) of marine debris and fishing gear (mostly hooks and lines from longline fisheries) were found in association with wandering albatrosses Diomedea exulans, and very few in association with grey-headed Thalassarche chrysostoma and black-browed albatrosses T. melanophrys. Despite increased observer effort, a slight decrease was observed in the total number of items encountered (n=116) compared with the previous season. Two non-fatal entanglements involving a wandering albatross and a northern giant petrel Macronectes halli were observed, and in both cases the fishing gear was typical of that used in longline fisheries. There were no incidences of hydrocarbon soiling of seabirds during the reporting period.

During the seventeenth year of standardised beach surveys of man-made debris at Bird Island, South Georgia (covering the period 1 October 2006 to 30 September 2007) a total of 365 items were collected. This represents a reduction by 33% on the 544 items recorded in 2005/06 and a decrease in mass of 1.72 kg (32%). The distribution of debris between the summer and winter was similar to the five previous years: 73% during summer (265 items) and 27% during winter (100 items). After three consecutive years in which no fisheries related debris was observed, one nylon fishing line and one snood were found on the survey beach during the summer, plus another snood in winter (August). Both snoods were clearly identified as being the end of a multifilament line where a hook would have been attached. Five multifilament fishing lines (from longliners) were found on the beach, all during the winter fishing season. Six plastic packaging bands were recovered, suggesting that measures introduced by CCAMLR to control their use onboard fishing vessels have yet to prove entirely effective. Fifty-six pieces of trawl web were recovered, mainly during the summer period. Miscellaneous debris such as plastic sheeting, Styrofoam packaging and other plastic items comprised the greatest proportion of items removed from the study beach (96% of the total).

Preliminary analysed data obtained from bottom fishing in 1987, 1989 from Cosmonaut and Cooperation Seas. Presented frequency of occurrence of immature Dissostichus mawsoni in catches of bottom trawls and juvenile Dissostichus mawsoni in catches of mid-water trawls during krill fishing in the same regions. Some grounds of these seas are permanent feeding places of Dissostichus mawsoni.

The exploratory fishery for Antarctic toothfish (D. mawsoni) has been operating for eleven years in Subarea 88.1 and for six years in Subarea 88.2. This report summarises the large amount of data collected on toothfish and the associated bycatch by all vessels participating in the fishery. All SSRUs in the two subareas except for 88.1D and 88.2C have now been fished. The 2008 D. mawsoni catch was the fourth highest on record with a total of 2666 t against a combined catch limit of 3207 t. The management of the SSRUs within the two subareas was changed for the 2006 season as part of a 3-year experiment (SC-CAMLR-XXIV). One of the aims of the experiment was to simplify the administration of the fishery by having fewer catch limits. This appeared to be moderately successful, with only one catch limit being slightly exceeded in the 2006 season, two catch limits in the 2007 season, and none in the 2008 season. The catch limit was under caught in both Subareas 88.1 and 88.2 during the 2008 season, primarily as a result of the ice conditions. The length frequency data from the Ross Sea fishery have been very consistent over the past 3–4 seasons. There is no evidence of any truncation of the overall length frequency distribution, and no evidence for a reduction in fish length in any SSRU over time. Although moderate numbers of small fish are caught in some years (e.g., on the Shelf in 1999 and 2001), these year classes are not seen in large numbers in later years in the fishery. So at this stage there is no evidence for strong variation in year class strength in the fishery.

A previous study on the age and growth of Amblyraja georgiana in the Ross Sea suggested that these skates initially grow very rapidly for about five years, after which growth almost ceases (Francis and Ó Maolagáin, 2005). We present an alternative interpretation of age and growth in A. georgiana that is radically different from the published interpretation. By counting fine growth bands in the caudal thorns instead of broad diffuse bands, we have generated growth curves that suggest much slower growth, greater ages at maturity (about 20 years compared with 6–11 years) and greater maximum ages (28–37 years compared with 14 years). Several pieces of circumstantial evidence support the new interpretation, but a validation study is required to determine which growth scenario is correct.

Photographs of skates taken by observers on New Zealand toothfish longliners in the Ross Sea were identified to species. Sample sizes were small, but indicated a ratio of 10.75:1 of Amblyraja georgiana to B. cf. eatonii, which is consistent with a previous estimate based on a large sample of tagged skates. Biological parameters were reviewed and updated for Amblyraja georgiana. Revised length-weight regression relationships for male and female A. georgiana confirmed that male and female relationships differ significantly. Better estimates of median length at maturity were made possible through a combination of improved observer staging of skates, and a moderate-sized sample of whole skates that was examined in the laboratory. There was no significant difference between the median length at maturity for male and female A. georgiana, which was estimated to be 67.3 cm pelvic length (= 96.5 cm total length). Nearly all of the skates caught were returned to the sea (discarded or tagged). A considerable proportion of these were returned in good condition and were considered likely to survive. Estimates of the proportion released in good condition are in the range 50–80%, depending on assumptions about whether skates were double counted, and whether all tagged skates were in good condition. Improved data recording using new fate and condition classes and a new data logsheet should provide better estimates of this parameter next year.

Conservation Measure 22-06, in the absence of site-specific or other conservation measures to prevent significant adverse impact on vulnerable marine ecosystems, requires specific actions to be taken when evidence of a Vulnerable Marine Ecosystem (VME) is encountered in the course of fishing operations. Monitoring fishing operations for encounters with evidence of a potential VME entails identification of specific taxonomic groups of invertebrates, such as sponges or corals. Identification of these organisms to the appropriate taxonomic grouping has not been a standard procedure, and no identification guide specific to both indicative VME taxa and Antarctic species has been developed. The objective of this guide is to provide observers on long-line vessels with a potential VME-taxa specific, quick, on-deck guide to aid in the classification of invertebrate bycatch into the appropriate groupings. The format of the guide is a “compare and contrast table”, using photographs and key characteristics to correctly classify likely VME taxa to the appropriate grouping. It also identifies those commonly mistaken for other taxa. It is printed as an A2 waterproof poster for display in the vessel factory or on deck for easy reference. Once classified, these observations can be used for monitoring evidence of a potential VME. Additional invertebrate identification guides are still needed for fine taxonomic resolution for all invertebrate bycatch.