CCAMLR

Results of samples’ processing fixed from Sub-area 88.1 in the 2003-2004 season aboard f/v «Yantar» operating in the Exploratory Fishery were presented.
According to the results of investigation of oocytes’ size composition and histological researches of ovaries at different maturation level it was ascertained that intermittent oogenesis type and synchronic development of the nearest spawning oocytes portion is characteristic of Antarctic toothfish. Absolute calculated fecundity was about average 1 million eggs and relative one was about 25 eggs per 1 g of body weight.
It was confirmed that the predominant part of pre-spawning individuals was concentrated over isolated sea mountains to the north of 70° S. It was demonstrated that some part of females participated in spawning not every season and missed spawning.
Data on fecundity of some by-catch species are given. State of Patagonian toothfish gonads’ maturity in Argentina Sea in March, 2004 is discussed.

The Patagonian toothfish (Dissostichus eleginoides) has been fished in the Kerguelen Islands zone for 20 years, firstly with trawlers and more recently with longliners. It is the oldest fishery of the Indian sector of the Southern Ocean. However IUU fishing has appeared in 1997. A GLM analysis has been performed from the statistical data of the legal fishery to assess the factors affecting the catch per unit effort (CPUE) both from the trawl and the longline fishery. The recent trends show a decrease of the CPUE, indicating a probable local overfishing. The bathymetric spreading of the fishery seems to have partially occulted this situation. In addition some biological facts (such as depth distribution, spawning date and place, and movements between geographical sectors), of the adult part of the population have been obtained from a scientific programme conducted by the fishery observers onboard the fishing vessels.

This document indicates our intention to get admission for adopting new longline system instead of Spanish longline system to exploratory longline fisheries for Dissostichus spp. in Subarea 48.6 in 2005/06 season, showing difference between two systems by two figures, and explaining the reason why we want to adopt new system with results of bottle test.

The First Meeting of the Advisory Committee to the Agreement on the Conservation of Albatrosses and Petrels was held in Hobart from 20-22 July 2005. This meeting followed the First Session of the Meeting of the Parties, held in Hobart from 10-12 November 2004.
Eleven Parties have ratified the Agreement of which six were represented at the Advisory Committee meeting. In addition three range states were represented as well as observers from CCAMLR, Birdlife International and SCAR.
The meeting examined issues associated with the establishment and operation of the Agreement Secretariat; noted reports from Parties and Signatories on activities relevant to the implementation of the Action Plan; reviewed reports from its Working Groups and agreed to establish a Working Group on Breeding Sites.
The meeting examined a number of papers submitted in relation to the issue of incidental mortality in fisheries. It was agreed that engagement with RFMOs was fundamental to improving the conservation status of many albatross and petrel populations and that ACAP should seek observer status at relevant RFMO meetings; FAO COFI; Regional Fisheries Bodies; and International Coalition of Fisheries Associations.
The meeting also noted the considerable work that had been done by CCAMLR to reduce seabird bycatch in CCAMLR waters and looked forward to continuing with this spirit of cooperation by maintaining a close working relationship between CCAMLR and ACAP.

A standardised CPUE analysis was used to determine factors affecting bycatch rates of rattails (Macrourus spp.) and skates in the exploratory fishery for toothfish in the Ross Sea (CCAMLR Subareas 88.1 & 88.2). The analysis was based on fine-scale haul-by-haul (C2) data and observer data from all vessels in the fishery from 1997/98 to 2004/05. The major factors influencing rattail bycatch were vessel, area, and depth. Catch rates of rattails were highest along the shelf edge (SSRUs 88.1E, 88.1I, 88.1K and 88.2E) in depths from 600 to 1000 m, and there was an order of magnitude difference in rattail catch rates between different vessels. Examination of vessel characteristics showed that catch rates of rattails were lower with the Spanish line system than with the autoline system. Russian and Korean vessels had extremely low catch rates compared to other vessels. Standardised CPUE of rattails has shown a general increasing trend since 1998/99, with a peak in 2002/03.
It was not possible to reliably determine factors influencing catch rates of skates from either C2 or observer data because a proportion of skates are cut free and released at the surface and these are not accurately recorded or reported in either dataset. There are a number of inconsistencies within the observer data which need to be resolved before these data can usefully be used for estimating bycatch. These include a consistent definition of a set across the observer and C2 datasets, accurate recording of the number of hooks observed for bycatch, and completion of the L11 form on the fate of skates for all sets.

Age estimates of mackerel icefish from different laboratories obtained during a CCAMLR ototlith exchange programme in the late 1980’s revealed considerable differences between readers when fish older than 3 or 4 years were aged. These differences could not be reconciled at the end of the exchange. A second age determination workshop on mackerel icefish to improve the accuracy of age determination was agreed upon at the last meeting of the ‘Working Group on Fish Stock Assessment’. Our report briefly summarizes the state of knowledge on age determination in mackerel icefish and assesses the validity of ageing. Possible ways forward were described to improve the validity of age determinations of the species.

This report presents results from a desktop study to consider approaches to monitoring and assessing rattails and skates, which are major bycatch species in the exploratory fishery for toothfish in the Ross Sea. We review standardised CPUE analysis, quantitative research longline surveys, experimental manipulation of fishing effort, catch-curve analysis, tagging programmes, bottom trawl surveys, and acoustic surveys.
We recommend that a random bottom trawl survey would be the best approach towards obtaining abundance estimates for rattails and skates in the Ross Sea. The major advantage of this approach is that preliminary stock assessments could be carried out for both species groups after only one successful trawl survey. Simulations have indicated that only 35–40 trawls would be required in the depth range 600–1500 m to obtain a precise estimate of bycatch abundance in the area of highest densities (SSRUs 881E, G, H, I, J, and K). A trawl survey could also be used in conjunction with other methods of monitoring abundance, e.g., skates caught during the trawl survey could be tagged and released, rattails could be aged for catch-curve analysis. The main limitations of this approach is the variable ice cover in the Ross Sea, which may restrict access to some areas, the rough bottom topography, and concerns about the environmental impact of bottom trawling on benthic communities. Tag-recapture experiments for skates and experimental manipulation of fishing effort are alternative methods which show some promise for monitoring abundance.

This report presents risk categorization tables for Macrourus whitsoni and Amblyraja georgiana, which are the major bycatch species in the exploratory fishery for toothfish in the Ross Sea.
Amblyraja georgiana were categorized as risk status 3 – species that are exploited as bycatch, and have a limited reproductive potential, and/or other life history characteristics that make them especially vulnerable to overfishing. The risk to A. georgiana is mitigated due to a CCAMLR programme to cut all skates from longlines whilst still in the water and release them. Macrourus whitsoni were categorized as between risk status 2 and 3 – although life history characteristics may make this species vulnerable to overfishing, catch rates in the toothfish fishery have not declined, juveniles are not selected by the fishery, and comparison of longline and trawl catch rates with other Antarctic areas suggest that population in the Ross Sea may be relatively large.

Juveniles of the macrourid rattail Macrourus whitsoni were collected by the NIWA research vessel Tangaroa during the BioRoss survey of the Western Ross Sea and Balleny Islands, with the purpose of analyzing the otoliths to generate more accurate age estimates for this species. Intensive analysis of otoliths from small specimens greatly increased confidence in the interpretation of the zone structure displayed in the early growth rings. The findings supported the interpretation protocols used in previous work on this species. Von Bertalanffy growth curves were generated and compared to previous results finding no significant differences between the years. Von Bertalanffy parameters for the pooled dataset with unsexed juveniles are L? 76.12, K 0.065 and t0 -0.159 for males and L? 92.03, K 0.055 and t0 0.159 for females. Revised estimates of the mean total length–at– maturity (38.8cm, 46.4cm) and mean age–at–maturity (10.6 years, 13.6 years) are presented for males and females respectively, using a reduced probit model.

During the 2005 fishing season experiments on the survivorship of post-tag toothfish were carried out on 8 different vessels fishing in 48.3. Toothfish were selected for tagging as normal, and then were kept in tanks with varying degrees of seawater replacement for at least 12 hours after tagging. On one vessel fish with a variety of injuries were selected to see if this affected recovery. 395 animals were included in the final analysis, with an overall survivorship of 89%. There were significant differences between vessels, and smaller animals and animals in better initial condition had a slightly higher survivorship.
There are indications that survivorship rates may be lower while observers are learning how to tag effectively and, perhaps, in experiments such as this if handling stress is increased. The results suggest that experienced observers using animals in good condition would normally achieve a survivorship of 95% or more. An assumption of 90% post-tagging survivorship would appear to be an appropriate, conservative, parameter to use in population estimators such as CASAL and mark-recapture.