CCAMLR

On the grounds of data analysis collected by one of the authors – Prutko V.G. in December, 2002-March, 2003 in Subarea 88.1, we determine Antarctic toothfish body length at maturity of 50% females -128-130 cm, males -117-120 cm.
To estimate maturity stages of post-spawning individuals we suggest using double designation, and to control visual estimation of maturity stages number of different oocytes in Antarctic fish ovaries should be measured and calculated, in addition to histological investigations. Dynamics of gonadosomatic index in different periods and for different research areas is presented. Presence of Antarctic toothfish spawning concentrations in the northern part of the research area and presence of “exhausted” individuals are noted. On the basis of the proceeded data and analysis of literature information we came to the conclusion that strict limitation of Antarctic toothfish catch was necessary. Together with the limitation it is suggested paying maximum attention to investigate reproduction ability of the species in question. Brief program of such research is presented.

Detailed materials are presented collected by the author in Subarea 88.1 in December, 2002-March, 2003 on penetration of sub-Antarctic species D.eleginoides, L.immaculatus to polar latitudes (to 72° S). Supposition is expressed that Ross’s rotation conditions mixing of Antarctic and Patagonian toothfish distribution areas and appearance of opah in the polar Ross Sea.

This paper provides an update on seabird research underway in New Zealand. Details of population research including methods and relevant references are provided. Foraging range tracking programme details are also provided, along with details of recorded visits to the CCAMLR area (nil).

Data on maturity, gonadosomatic index (GSI) and length weight of Antarctic toothfish Dissostichus mawsoni were collected from Sub-area 88.1 in the 2002-2003 season by the New Zealand bottom longline vessels Janas, Avro Chieftain and San Aotea II operating in the Exploratory Fishery. The first spawning fish were found in April, a month earlier than in the previous season.

An update on the BioRoss research programme is provided for information purposes. The update includes progress to date, planned research and the future of the programme.

An exploratory fishery for Antarctic toothfish (D. mawsoni) has been in operation for six seasons in Subarea 88.1 and for two seasons in Subarea 88.2. A large amount of data on both toothfish and associated bycatch from the fishing operations has been collected. The purpose of this report is to present the analysis of data collected in the toothfish fishery for the 2003 season (this is part of the 2002–03 CCAMLR split fishing year), and to compare these results with previous years. Note this report is confined to data for the New Zealand vessels.
The heavy ice conditions caused by the presence of the huge C2 iceberg severely altered the fisher's behaviour in 2003. The vessels were unable to fish south of about 72º S, and so effort was mainly focused instead on SSRUs 881A–C. In addition, SSRU 882E was fished for the first time.
Ninety-two fine scale rectangles (FSRs), including 57 new FSR’s, were fished during the 2003 season. New Zealand vessels have now fished a total of 228 FSRs.
The catch of D. mawsoni was about 1070 t, and contributed 89% of the total catch in 2003. They were caught in over 90% of the sets in all five SSRUs fished. They were the dominant catch in all sets apart from some made in SSRU 881A. Antarctic toothfish were recorded at depths from 430 to 1900 m, and were most abundant from about 1000 to 1800 m. In 2003, almost 25 t of Patagonian toothfish (D. eleginoides) was taken, almost entirely from SSRU 881A. This is more than twice the catch from 2002 but not as great as the catch from 2001. Patagonian toothfish dominated the catches from 60 to 62° 30' S but Antarctic toothfish dominated catches further south.
The main bycatch species was Macrourus whitsoni, which contributed about 7% of the 2003 catch. Two other rattail species were identified from 5 sets. Bycatch of the two skate species (Amblyraja georgiana and Bathyraja eatonii) was only 6.3 t (less than 1% of total catch). Other bycatch species (including icefish and moray cods) each contributed less than 1% of the catch overall. The main non-fish bycatch reported was starfish.
Antarctic toothfish length frequency data were scaled up to the catch. About 530 otoliths were read and the scaled length frequency converted to catch-at-age. Fish aged from 13 to 30 years dominated the catch. No progressions of any particularly strong or weak year classes were apparent throughout the time series. Length and age of Antarctic toothfish from the fishery have increased through the series, mainly because fishing has been directed more toward depths greater than 1000 m in the later years.
Length frequency data for Macrourus whitsoni from 2002 and 2003 were scaled up to the catch for each year. Also age, growth, and maturity data were reviewed.

A toothfish fishery has operated during the Antarctic summer (December - May) from 1997 to 2003, in Subareas 88.1 and 88.2 in the region of the Ross Sea. A preliminary standardised analysis of toothfish CPUE (catch (kg) per baited hook per set) carried out last year compared three alternative toothfish CPUE analyses for the 1998 to 2002 seasons. The analysis of a data subset including only the two main vessels and the 3 main fishing grounds was the best fit to the data.
This report updates the main grounds and vessels analysis to include the 2003 season. Seasonal indices were variable with no trend, and error bounds on the estimates were low, but the main grounds analysis model was a relatively poor fit to the data. The variables depth, soaktime, length of line, area, and season, entered the model, which explained 37% of data variability. Because of the poor diagnostics, the model was fitted to sets excluding zero catches of Antarctic toothfish as a sensitivity. The diagnostics for this model were substantially improved and the seasonal indices were slightly more optimistic. As fishing effort has extended to other grounds since 2001, a further sensitivity analysis was completed for the two main vessels. The seasonal indices were similar to the main grounds analysis. While the model explained 48% of data variability, it was influenced by the unbalanced nature of the data, and model diagnostics indicated a poor fit to the data.
Data are available from seven seasons, but the analysis was confined to the two vessels with a consistent fishing history, and as such only represents a small area of the entire Ross Sea toothfish fishery. The variables included in the analysis are plausible, but the models may be influenced by extreme values of soaktime, depth and length of line set, that reflect the exploratory nature of the fishery. The descriptive power of the main grounds model is reasonable, but it is still influenced by the unbalanced nature of the fishery and records of zero catches.
Seasonal indices show no trend between 1998 and 2003, but the relationship between these indices and relative abundance is unknown, and fishery independent data are unavailable to validate this relationship. Standardised CPUE indices have been validated for overseas longline fisheries, including Alaskan sablefish (Anoplopoma fimbria), Atlantic halibut (Hippoglossus hippoglossus), and Atlantic cod (Gadus morhua), using tagging, acoustic survey, and quantitative longline survey methods. These species have generally similar biology, distribution, and fisheries operation to Antarctic toothfish. Therefore, trends in standardised CPUE indices could be directly related to relative abundance for toothfish. The toothfish standardised CPUE data provide an index of fishery performance. Continued monitoring of CPUE for the main grounds, main vessels is recommended, and further research on other possible CPUE models, and inclusion of first order interactions in the analysis is suggested. Research into suitable methods for validating the relationship between CPUE seasonal indices and the relative abundance of toothfish is also recommended.

Scientific observers collected maturity data from skates caught by New Zealand longline vessels targeting toothfish in the Ross Sea during 2002–03. Sample sizes were small, making it difficult to obtain accurate estimates of the length at 50% maturity. Results were compared with data collected in the previous season.
The length at 50% maturity for male Amblyraja georgiana is about 92 cm TL. Females appear to mature at a slightly greater length of 95–100 cm TL, but further data are required to confirm this. The length at 50% maturity of male and female Bathyraja eatonii could not be accurately determined, but may be around 85–90 cm and 100–120 cm, respectively.

Information on mackerel icefish that has been presented at WG-FSA is summarised and the information augmented by reference to published papers. The New Zealand government has released a draft National Plan of Action – Seabirds. The plan will apply to commercial and non- commercial fishing in New Zealand fisheries waters. It will also apply to high seas fisheries in which New Zealand flag carrying vessels participate. The plan proposes that Codes of Practice be developed for each fishery, and that the Codes specify fishing practices that will be adhered to, maximum bycatch limits, and methods to monitor compliance, education and public awareness. Specific fishing practices and bycatch limits will be made mandatory if not adhered to voluntarily in Codes of Practice. Economic incentives or penalties may also be developed if required. The New Zealand government will make final decisions on the plan in November 2003, following feedback from stakeholders.