CCAMLR

The North Pacific Fishery Management Council (Council) recommended changes to the existing regulations for seabird avoidance measures required in the groundfish and halibut demersal longline fisheries off Alaska. One of the main recommendations is for the required use of paired streamer lines on larger vessels. Changes were based on research results from a two-year study conducted by the Washington Sea Grant Program (WSGP) on the effectiveness of seabird avoidance measures in the longline fisheries off Alaska. For complete details of the research, results, and recommendations, see the WSGP final report. The report, “Solutions to Seabird Bycatch in Alaska’s Demersal Longline Fisheries”, is available at http://www.wsg.washington.edu/pubs/seabirds/seabirdpaper.html and was submitted to CCAMLR in 2001 (WG-FSA 01/35). Rigorous experimental tests of seabird avoidance measures on the local abundance, attack rate, and hooking rate of seabirds in Alaska fisheries were conducted on vessels over 60 ft (18.3 m) LOA. Paired streamer lines of specified performance and material standards were found to successfully reduce seabird incidental take in all years, regions, and fleets (88 percent to 100 percent relative to controls with no deterrent). This proposed action is prompted for two reasons: 1) An industry request to the Council to strengthen the seabird avoidance measures, and 2) the availability of research results from a study on the effectiveness of seabird avoidance measures that suggest ways that the current seabird avoidance requirements can be improved.
The objective of the proposed regulatory change is to revise the current seabird avoidance requirements to improve their effectiveness at reducing the incidental take of endangered short-tailed albatrosses and other seabird species. The National Marine Fisheries Service (NMFS) is currently promulgating regulatory changes based on the Council’s recommendations.

In 2001, WG-FSA asked the Intersessional Subgroup on Sampling Catches from Longlines to develop recommendations on 1) subsampling methods using frames and sampling units based on time and gear; 2) the allocation of observer effort within longline haul and between hauls; and 3) the allocation of observer effort directed toward fishery target species versus ecological interactions. Both subsampling methods use the hauling completed within a day as a frame, and theoretically cover all fishing activity by sampling every day of hauling. Both methods essentially follow a multi-stage cluster sampling design, which could be implemented more rigorously if the CCAMLR objective was changed from sampling 60 fish/day, to sampling a set length of each line or number of hours of each day. The principal advantage of the time-based method is that it gives a frame that can be monitored easily using a watch, but the frame is based on the mean time that is taken for hauling which is itself a random variable. The gear-based approach uses a fixed frame, but monitoring the amount of line hauled can be difficult when sampling the target species. Sensitivity analyses used to examine present guidelines on sample sizes, indicated that increasing the number of fish sampled for length would not substantially increase the precision of the estimates for mean length. From the limited evidence available, seabird mortality rates are estimated sufficiently precisely at 25% coverage to be reasonably sure of detecting increases to unacceptable levels. Sampling toothfish for biometric data in the factory and observing the incoming line may usefully be allocated to different days, if done so randomly.

This report presents results from the first exchange of otoliths under the auspices of the CCAMLR Otolith Network (CON), following the Workshop on Estimating Age in Patagonian Toothfish held at the Centre for Quantitative Fisheries Ecology (CQFE), Old Dominion University, United States, from 23 to 27 July 2001. The National Institute of Water and Atmospheric Research, Nelson, New Zealand; Central Ageing Facility, Victoria Australia; and CQFE, each provided a sample of otoliths, processing and reading one randomly chosen otolith from each pair. Half of the remaining otoliths were sent to each of the other laboratories to process and read using their methodologies. Overall there was reasonable agreement in age estimations between all three readers, with no evidence of biases >2 years that would indicate major differences in the criteria used by the readers. Similarly, there was little evidence that the differences in preparation technique led to major biases or increases in variation in the ages estimated. Instead, there appears from these data to be a broad consensus on the otolith micro-features that need to be exposed during preparation, and the way to interpret them. Small biases and variance in several cases may be explained by apparent differences in the timing of formation of translucent zones between management areas, and readers’ interpretation of the first few translucent zones. Future CON exchanges should 1) define better how these differences in interpretation may affect age estimates, and 2) achieve consensus on their interpretation.

Framework for IPOA-Seabirds implementation and structure of NPOA-Seabirds is discussed. Interagency cooperation as well as international cooperation is vital for the efficient and effective implementation of IPOA and NPOA. Education and outreach activities are listed. Numerous opportunities for international outreach and cooperation occurred in 2002.

Estimates of age and growth were determined from 156 Macrourus carinatus otolith samples collected during two research voyages to Heard and McDonald Islands (Division 58.5.2) in 1992 and 1993. The estimated range of ages was 4 – 25 years. von Bertalanffy growth parameters were calculated for both sexes combined, resulting in values of: L8 = 635 mm, K = 0.088 and t0 = -1.8. The size at sexual maturity of M. carinatus was determined from 162 specimens collected during commercial fishing operations in the Heard Island region in 2000. The size at which 50% of the fish population is mature, L50 was 417 mm total length and the size at which 50% of the fish population have spawned for the first time, Lm50 was 512 mm total length. An updated length-weight relationship is provided from 633 specimens of M. carinatus collected from Heard and McDonald Islands and Macquarie Island. No difference was evident in the length-weight relationship from the two regions. Otolith and body size relationships were also calculated for M. carinatus from Division 58.5.2.

A survey of mackerel icefish, Champsocephalus gunnari, was undertaken in Division 58.5.2 in the vicinity of Heard Island in May 2002 to provide the information for an assessment of yield in the 2002/2003 CCAMLR season. This paper provides a preliminary assessment of yield using the assessment methods of CCAMLR and discusses the implications of these results in relation to previous CCAMLR assessments. The estimate of biomass of mackerel icefish for the population at Heard Island was not significantly different from previous years but the one-sided lower 95% confidence bound was greater than in 2001 probably because the population was more uniformly spread in the southeast with relatively high densities in that stratum. The composition of the population was observed to comprise a single large cohort of mostly three and four year old fish in May 2002. Given the size of the fish, the expectation from current estimates of length at age parameters would be for most of the fish to be three year olds. However, given the abundance of fish in the population and the age structure of fish last year, it would be more reasonable to conclude that most of the fish are four years old, as this age class comprised the larger fraction (93%) of the population last year. Two assessments were undertaken as a result of the potentially different interpretations as to the composition of the larger cohort. If the cohort comprised mostly three year old fish then the yield for 2002/03 is estimated to be 1990 tonnes. If it comprises mostly four year olds then the yield would be 1815 tonnes. It is also proposed that the minimum size of capture be increased for 2002/03 to protect the younger unassessed cohort of fish from being exploited as they potentially enter the fishery towards the end of the season.

This paper presents estimates of the total removals of fish and invertebrate bycatch by fishing season and fishing ground, from the D. eleginoides and C. gunnari trawl fisheries in Division 58.5.2. On average, 94 % of hauls in the D. eleginoides fishery and 93% of hauls in the C. gunnari fishery were observed. The percentage of observed hauls was used as a scaling factor to convert observed bycatch weights to estimates of total bycatch removed from the fishery. Bycatch in these trawl fisheries is very low. From 1996/97 to 2001/02, a total of 95 tonnes of bycatch was caught in the D. eleginoides fishery and 46 tonnes in the C. gunnari fishery. These values represent 1 and 2% respectively, of the total catch weight (target and non-target species) in each fishery. The composition of the bycatch is described by fishing ground and fishery. The operation of the ‘move-on’ rule, which aims to minimise localised depletion of bycatch is also discussed.

The proposals for comparative tests of bottom trawls are presented. The following sections are discussed: place and time of realization; preparatory works; comparative trawlings; acoustic support; observation data processing.

Results of the acoustic survey of icefish carried out by Russian vessel STM-8390 Atlantida in February-March 2002 in Subarea 48.3 are presented. Biomass and distribution of icefish were obtained using multi-frequency echosounder EK-500 and Sonar Data EchoView software.
Target strength estimates of icefish were made by comparison an observed TS in situ histograms with the size composition of the ensonified fish, obtained by trawling.
Results of acoustic estimates of icefish biomass and abundance values by size class in pelagic zone and in the near-bottom 8m layer (covered by bottom trawling survey) are discussed. The major part of pelagic biomass was concentrated within 50m above the bottom 8m layer and amounted to 23,037.4 tonnes. This estimate can be considered as the minimum value of the pelagic component of the icefish stock, since it does not take into account the biomass of the fish distributed within higher depth ranges where, according to the data of trawling and acoustic sampling, icefish are also available. The bottom biomass resulted in the estimate of 62,328.0 tonnes. The sum acoustic estimate of the icefish biomass in the subarea of South Georgia amounted to 92.6 thous. tonnes. Nearly 30% of this biomass was concentrated in the pelagic zone. If acoustic estimates of pelagic and bottom components of the icefish biomass are compared it will become evident that the pelagic part of biomass makes up nearly 42% of the bottom biomass. Our acoustic estimate of the pelagic biomass constitutes about 60% of biomass obtained from bottom trawling survey.
In additional to the above-states estimates the abundance of juvenile fishes (speciments less than 6cm) was obtained in the sub-surface 50-m layer where, according to trawl samples, the latter predominated. Sum abundance of young fish constituted 7344.6 million pcs.
The horizontal and vertical distributions of krill with reference to investigation of regularities of icefish behavior and distribution are discussed.