CCAMLR

Fecundity and size at sexual maturity were investigated in 486 bigeye grenadier, Macrourus holotrachys caught as bycatch in the Patagonian toothfish longline fishery conducted around South Georgia. Macroscopic and histological investigations revealed that absolute fecundity ranged from 22,000 to 260,000 eggs, a relatively high number for a macrourid. Mature ovaries were found to contain eggs at different stages of development suggesting that M. holtrachys may have an extended spawning season. Analyses of size at sexual maturity indicate that Lmat 50 occurs at 29cm (pre-anal length) whilst Lint 50 occurs at 20.57cm. The large difference between these values strongly suggests that yolk deposition and final ovarian development is a prolonged process in M. holotrachys which probably lasts for a period of greater than a year. Sex ratios of specimens caught in the longline fishery are highly skewed with females outnumbering males by a ratio of 32:1 which may represent the true ratio of females to males within the population or could suggest that females are more susceptible to capture by longlines than males.

Longlines that sink fast reduce the time available to seabirds to attack baited hooks and are important in efforts to minimise seabird by-catch in longline fisheries. We measured sink rates in still water of longlines made by Fiskevegn, the world’s leading manufacturer of demersal longlines. Lines with integrated weight (lead cores) sank two-three times faster (45- 52 cm/second) than conventional (unweighted) lines. Conventional lines made from 9 mm polyester sank at 23 cm/second compared to 18 cm/second for Silver lines of the same diameter. Samples of lines set by hand in still water sank significantly faster than longlines set from a fishing vessel.

Germany conducted a bottom trawl survey aboard R/V ‘Polarstern’ around Elephant Island and the South Shetland Islands in January – February 2002 in close collaboration with the U.S. Antarctic Marine Living Resources Program (AMLR). Information on species composition, biomass, and size distribution of the abundant fish species was provided. Estimates of total biomass for Elephant Island and the South Shetland Islands separately were computed for Notothenia rossii, N. coriiceps, Lepidonotothen larseni, L. squamifrons, Gobionotothen gibberifrons, Champsocephalus gunnari, Chaenocephalus aceratus and Chionodraco rastrospinosus. For these species, biomass estimates were found to be 3 comparable to survey results obtained in 1998 and 2001 for most species. Length compositions in the most abundant species resembled closely those in previous years. The proportion of juvenile G. gibberifrons, the most abundant species in the region, decreased significantly since 1998. No indication was found for the presence of a significant adult stock of N. rossii at Elephant Island where the species was known to occur in some quantities prior to commercial exploitation in 1979/80. It should be noted that more than 95 % of the population of N. rossii prior to exploitation was confined to a comparatively small area north of the island and may have been missed by a survey not specifically directed at N. rossii. It is suggested to conduct a specific survey targeting N. rossii in the near future to properly assess the status of this stock.

Conservation Measure # 216 requires vessels fishing in sub area 88.1 + sink longlines at 0.3 m/s to 15 m depth. Sink rates can be achieved by adding external weights to lines or by using lines with weigh integrated into the rope fibres. The sink rates to 15 m depth of 9 mm demersal longlines with integrated weight (IW) were tested against unweighted longlines and lines with externally attached weights (6 kg/49 m) in the New Zealand ling fishery. Longlines with 0 g/m (unweighted), 25 g/m, 50 g/m 75 g/m and 100 g/m integrated weight averaged 0.11 m/s, 0.227 m/s, 0.272 m/s, 0.317 m/s and 0.353 m/s, respectively. The longline with externally attached weights sank at 0.32 m/s. IW longlines sank instantly, reaching 1 m depth in 6-9 s whereas unweighted lines took >20 s to reach this depth. Catch rates of ling varied with line weight but results are indeterminant due to the small sample sizes. No operational effects of using IW lines were evident during the trial. IW longlines containing 50 g/m added weight are recommended for testing in a subsequent trial to examine the effectiveness of IW longlines in reducing seabird mortality in autoline longline fisheries.

Germany, in close collaboration with the United States Antarctic Marine Living (U.S. AMLR) Program, conducted an investigation of an 7 x 10 nm ‘box’ between 100 and 300 m depth to the west of Elephant Island (Subarea 48.1) in order to study the meso – scale abundance of demersal finfish species. Diversity in the box was relatively low. The most abundant species were Gobionotothen gibberifrons and Champsocephalus gunnari. Their distribution was very patchy even on a meso-scale. Concentrations of both species were found in a comparatively small band primarily along the 200 m isobath (160–240 m). Length distribution changed with fishing depth in C. gunnari, where larger fish were found predominantly in the stratum 200– 300 m.

Germany conducted a bottom trawl survey aboard RV ‘Polarstern’ around Elephant Island and the lower South Shetland Islands in January–February 2002 in close collaboration with the US Antarctic Marine Living Resources Program (AMLR). Length–weight relationships were similar in the two areas for those species for which an extended length range was covered (Chaenocephalus aceratus, Champsocephalus gunnari, Lepidonotothen larseni, L. squamifrons) but was more variable in species where the length range caught was limited as in Notothenia rossii or Chionodraco rastrospinosus. Information on gonado–somatic indices was provided for C. aceratus, C. gunnari, Chionodraco rastrospinosus, Cryodraco antarcticus, Notothenia coriiceps and Trematomus eulepidotus. Dietary studies demonstrated that C. gunnari fed on krill and to an unusually large extent on fish. C. aceratus up to 30 – 35 cm length took primarily krill and mysids. When they grew larger they likely became more sedentary and fed primarily on fish. C. rastrospinosus preyed primarily on krill and to a minor extent on fish. C. antarcticus took primarily fish.

The results of researches carried out in expeditions of S?? “?tlantida” in summer-autumn period of the southern hemisphere from 30 January to 14 March 2002 are presented. These researches included the bottom trawl survey on the shelf of South Georgia, Shag Rocks and Black Rocks (53?10-55?30 S, 35?40-42?50 W); the acoustic survey with control hauls targeting recorded aggregations on the South Georgia shelf (53?10- 55?30 S, 34?00-39?40 W); series of oceanographic observations.

Two species of albatross breed in Chile, namely Thalassarche melanophrys and T. chrysostoma, and feed both in Antarctic waters and the South-eastern Pacific. Consequently they are subject to two different management regimes. This fact and the article XI of the CCAMLR Convention, suggests the need of harmonizing conservation measures in both areas. In this progress report we describe the main outcome of two research programs that are currently underway, which aim to establish if the effect of the long-line fishery is similar to that found in CCAMLR waters. The objective of this paper is to inform other CCAMLR members and observers these results in advance of scientific publications arising from these initiatives.

This paper summarises seabird bycatch during 1 July 2001-30 June 2002 of sanctioned longline fishing for Patagonian toothfish Dissostichus eleginoides in the Exclusive Economic Zone around South Africa’s Prince Edward Islands. Data were obtained from fishery observers aboard all nine sanctioned fishing trips. Fishing effort was 2.9 million hooks, a 36% reduction on the number of hooks set in 2000/2001 (Ryan & Watkins 2001). The number of seabirds reported killed by the observers was three birds: two White-chinned Petrels Procellaria aequinoctialis and one Grey Petrel P. cinerea . Average seabird bycatch rate by sanctioned vessels was 0.001 birds per 1 000 hooks which is a significant drop from the previous season when 0.009 birds were killed per 1000 hooks.