CCAMLR

In this paper we describe in situ observations on nesting by the Scotia Sea (or blackfin) icefish Chaenocephalus aceratus that constitute the first substantive evidence of egg brooding and parental care by species of the family Channichthyidae. These novel observations are enriched by descriptions of the seafloor community that is impacted by fish nesting. Given the vulnerability of spawning grounds and their associated megafauna to damage by bottom trawling and the associated impact on recruitment to adult fish populations, we argue that appropriate management of icefish fisheries must exclude or severely restrict fishing techniques that damage the seabed.

A toothfish fishery has operated during the Antarctic summer (December - May) from 1997 to 2004, in Subareas 88.1 and 88.2. A preliminary standardised analysis of toothfish CPUE (catch (kg) per baited hook per set) carried out in 2003 compared two alternative toothfish CPUE analyses for the 1998 to 2003 seasons for Subarea 88.1.
This report revises and updates the previous analysis with the addition of data from the 2004 season using data sets based on all vessels and the two main New Zealand vessels that have been in the fishery over the entire time period. However, the fishing grounds were changed to reflect the new SSRUs used to manage the fishery, and the larger regions used to assess the fishery (Dunn et al. 2005). It also examines alternative approaches to modelling catch and effort data by using mixed-effect models following Candy (2003).
The variables entering each of the three models were similar and all explained a reasonable amount (35-46%) of the variation. The variables included in the analysis are plausible, but the models may be influenced by extreme values of soaktime and depth that reflect the exploratory nature of the fishery. Model diagnostics show a reasonable pattern in the residuals for all models, but the quantile-quantile plots indicate a deviation from the normal distribution of the residuals at either end for the lognormal GLM models, and at the lower end for the fixed effects of the mixed model. This suggests that extreme values of catch rate were not modelled well and there may be violations of model assumptions.
The CPUE indices showed consistent trends in all three models. The indices were essentially flat apart from a slight decline in 2001 and a large decline in 2004. The reason for the large decline is unclear, but may reflect the bad ice conditions in 2004 as well as increasing competition between the large number of vessels operating in the fishery.
The relationship between these indices and relative abundance is unknown, and fishery independent data are unavailable to validate this relationship. Continued monitoring of CPUE for the main grounds and main vessels is recommended. Also 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.

The National Marine Fisheries Service (NMFS) contracted with the International Pacific Halibut Commission (IPHC) for a project examining the feasibility of electronic monitoring systems (EMS) in the Pacific halibut longline fleet operating off the state of Alaska. The project was conducted on two of the IPHC stock assessment survey vessels fishing in Alaska during 2002. The objectives of the project were to: 1) examine the ability of an electronic monitoring system to provide images that would allow an analyst to monitor seabird avoidance devices for regulatory compliance; 2) determine the feasibility of using video images for detecting and identifying incidentally-caught seabirds; and 3) discuss options for the future use of electronic monitoring as a fishery management tool.
To determine if EMS could be used to assist in compliance determination, an EMS system was installed on two halibut longline vessels chartered by the IPHC. Cameras were placed on the stern and recorded images of halibut gear being set and the performance of seabird avoidance devices, or streamer lines, during the setting. Vessel and video observations were compared on 106 setting events. The video observations determined that the EMS was successful in detecting streamer line deployment and relative position on 100% of the daytime sets when two setting cameras were operating together. The results of the streamer line performance evaluations suggest that accurate performance recognition was positively related to the increase in image recording speed and the video analysts’ ability to distinguish measured interval markings that were attached to the streamer lines.
The ability of a video analyst to recognize and identify the species of retrieved seabirds was examined by intentionally setting previously-caught frozen seabirds on the fishing gear. No birds were caught incidentally during this study. The results indicated that correct seabird identification is related both to the analyst’s knowledge of distinguishing species characteristics, and to the size of the seabird.
In conclusion, this study indicates that an EMS monitoring program would produce accurate data and enable compliance evaluations for seabird avoidance devices. In addition, an EMS program would be able to detect a high proportion of incidentally caught seabirds. However, additional work is needed on seabird image identification and verification methods and testing the effects of soak time on the physical characteristics of seabirds.

Archipelago Marine Research Ltd. Was selected by the Alaska Fisheries Science Center to test electronic monitoring (EM) equipment for possible use to examine seabird interactions with trawl third-wire cables on trawl vessels. This pilot study involved field testing of EM systems on shoreside delivery and head and gut bottom trawl vessels conducting operations in the Bering Sea, U.S. Exclusive Economic Zone. EM systems, consisting of two closed circuit television cameras, GPS, hydraulic and winch sensors, and on-board data storage, were deployed on five fishing vessels for 14 fishing trips during a one-month period in the fall of 2002. Detailed analysis of about 200 hours of fishing imagery occurred, representing 20 shoreside delivery vessel fishing events and 32 head and gut fleet fishing events. Results from the study demonstrated that EM could effectively monitor seabird interactions with trawl third-wire cables. The EM system provided imagery of sufficient quality to detect the presence, abundance, and general behaviour of seabirds during most daylight fishing events. As well, EM-based imagery was also able to detect third-wire entanglements of seabirds although it was not possible to determine the cause of these entanglements. EM imagery was not very useful for seabird enumeration and species identification. In regard to monitoring seabird interactions with trawl third-wires, EM would be suitable for monitoring the use and effectiveness of mitigation measures.

Archipelago Marine Research Ltd. Was selected by the Alaska Fisheries Science Center to test electronic monitoring (EM) equipment for possible use to examine seabird interactions with trawl third-wire cables on trawl vessels. This pilot study involved field testing of EM systems on shoreside delivery and head and gut bottom trawl vessels conducting operations in the Bering Sea, U.S. Exclusive Economic Zone. EM systems, consisting of two closed circuit television cameras, GPS, hydraulic and winch sensors, and on-board data storage, were deployed on five fishing vessels for 14 fishing trips during a one-month period in the fall of 2002. Detailed analysis of about 200 hours of fishing imagery occurred, representing 20 shoreside delivery vessel fishing events and 32 head and gut fleet fishing events. Results from the study demonstrated that EM could effectively monitor seabird interactions with trawl third-wire cables. The EM system provided imagery of sufficient quality to detect the presence, abundance, and general behaviour of seabirds during most daylight fishing events. As well, EM-based imagery was also able to detect third-wire entanglements of seabirds although it was not possible to determine the cause of these entanglements. EM imagery was not very useful for seabird enumeration and species identification. In regard to monitoring seabird interactions with trawl third-wires, EM would be suitable for monitoring the use and effectiveness of mitigation measures.

The environmental and/or life history factors affecting genetic exchange in marine species with potential for high dispersal are of great interest, not only from an evolutionary standpoint but also with regard to effective management. Previous genetic studies have demonstrated substantial differentiation among populations of the Patagonian toothfish around the Southern Ocean, indicating breakdown of gene flow across large distances between inhabited shelf areas. The present study examined genetic structuring through analysis of microsatellite loci and restriction fragment length poymorphism (RFLP) of the mitochondrial ND2 gene and control region of the toothfish population in the SW Atlantic, allowing examination of the relative effects of the Antarctic Polar Front (APF), deep-water troughs and distance between sites. Mitochondrial DNA (mtDNA) data indicated a sharp genetic division between the Patagonian Shelf/North Scotia Ridge and the Shag Rocks/South Georgia samples, whereas microsatellite data showed much less distinct structuring and an intermediate position of the North Scotia Ridge samples. We suggest these data indicate that the APF, as a barrier to larval dispersal, is the major inhibitor of genetic exchange between toothfish populations, with deep-water troughs and distance between sites contributing to genetic differentiation by inhibiting migration of relatively sedentary adults. We also suggest that differences between mtDNA and nuclear DNA population patterns may reflect either genome population size effects or (putative) male-biased dispersal.

An exploratory fishery for Antarctic toothfish (D. mawsoni) has been in operation for seven seasons in Subarea 88.1 and for three seasons in Subarea 88.2. A large amount of data on toothfish and the associated bycatch from the fishing operations has been collected. This report is somewhat different to earlier reviews of the exploratory fishery. In the first instance, it reports catches by the new SSRUs used to manage Subarea 88.1; secondly, the report includes catch data from all countries fishing in the area, whereas previous reports included data from only New Zealand vessels; and thirdly, the reported catch is confined to C2 data.
The catch of D. mawsoni was 2414 t, and contributed 87% of the total catch in 2004. D. mawsoni was the dominant species caught in all 12 SSRUs fished. In 2004, about 12 t of Patagonian toothfish (D. eleginoides) was taken, almost entirely from SSRU 881B. The main bycatch species was Macrourus whitsoni, which contributed about 11% of the 2004 catch. Bycatch of skates (mainly Amblyraja georgiana) was only 19 t (less than 1% of the total catch1). Other bycatch species (including morid cods, icefish and moray cods) each contributed less than 1% of the catch overall.
Because of changes in the ice conditions and fleet composition, no two seasons have been the same. In 2001, 2003, and 2004, ice conditions restricted fishing and resulted in new areas being explored. The change in fishing patterns between seasons is reflected in the mean length and age composition of the catch. In the past few seasons, there has been a trend towards fishing in deeper water and this is reflected in an increase in the length and age of the toothfish catch and in the bycatch, particularly the increase in catch of morid cods and icefish.
An approach to allocating the rattail catch to the SSRUs in Subarea 88.1 was examined. The indicative catch limits appear to be little better than the catch limits set for the 2004 season. Further examination of the problem is warranted.

Experimental fishing for Patagonian toothfish took place during the period from 28 June to 27 July, 2003. This experience was carried out by a Spanish longliner, following commercial procedures, in a restricted area south of Madagascar and north of the Prince Edward and Marion Islands and the Crozet Islands, and outside EEZ and CCAMLR waters. A total of 57 sets were taken at between 360 and 1950 metres depth. The Patagonian toothfish appeared in all those sets carried out with values comprised between 53 and 1158 kg. Northward distribution of Patagonian toothfish is closely related to the extension of the sub-Antarctic Front to the north. The prospected area would seem to be located at the edge of the main ground, in which a residual recruitment effect persists. The total CPUE was 42.21 kg/1000 hooks. Depth is the most important factor in Patagonian toothfish distribution within the study area.

Based on the last year's record of the operation and the advice by WG-IMAF/WG-FSA, the extension of the fishing season for the exploratory longline fishery for Dissostichus spp. in Statistical Subarea 48.6 north of 60°S is proposed.