CCAMLR

Variables of prey availability between inshore and slope/offshore foraging areas were compared to evaluate important factors for the formation of foraging areas of Chinstrap penguins (Pygoscelis antarctica) and Antarctic fur seals (Arctocephalus gazella) at Seal Island. Advantages of foraging inshore are: 1) proximity to breeding colonies and 2) high krill (Euphausia superba) abundance, whereas those of foraging slope/offshore are: 3) less patchy krill distribution, 4) shallow krill distribution, 5) larger krill size and 6) occurrence of energy-rich bioluminescing myctophid fish at night. Chinstrap penguins foraged in two modes during chick-brooding period: daytime foraging chinstrap penguins foraged in the inshore region, while overnight foraging penguins foraged in the slope region. It was suggested that important factors for the formation of daytime foraging areas may be mainly 1), while those of overnight foragers may be primarily 3) and secondarily 6) considering chinstrap penguins may have difficulty in perceiving prey at night. Antarctic fur seals foraged mostly in the slope/offshore region during pup-rearing period. It was suggested that important factors may be mainly 4) and 6). In conclusion, feeding success may not be necessarily associated with dense aggregation of krill, but with distribution pattern of krill which enhance prey capture, and availability of myctophid fish.

During a research cruise of the British Antarctic Survey ship RRS James Clark Ross in February 1996, a substantial number of the ommastrephid squid, Martialia hyadesi, were caught in a pelagic trawl, near the Antarctic Polar Frontal Zone in CCAMLR Subarea 48.3. This paper describes acoustic data gathered during this haul and a survey of the immediate vicinity, in order to characterise an acoustic signature that may be used to identify this species of squid.

The effectiveness of a split-beam echosounder system to delineate single scatterers and accurately measure in-situ target strengths (TS) is dramatically enhanced (98.2 -99.4%) by combining synchronized signals from two or more adjacent split-beam transducers of different frequencies. The accuracy of the method was determined through controlled test tank experiments using multiple standard spheres and 38 and 120 kHz split-beam transducers. Furthermore, by utilizing the angular position information from one of the split-beam transducers, additional corresponding TS measurements can be collected with juxtaposed single-beam transducers. Both methods were utilized to extract in-situ TS measurements of Antarctic scatterers simultaneously at 38, 120, and 200 kHz. Differences in the resulting TS measurements provided information about the identity of constituents in a mixed species assembly.

Catch Per Unit Effort data are presented from krill fishing operations in CCAMLR Subareas 48.1 , 48.2, 48.3 for the period 1975/76 to 1987/88. Comparisons are carried out between Subareas in single years, between years on a Subarea and Area basis, and between oceanic and shelf regions. Results show that the CPUE may differ between Subareas, years and shelf/oceanic regions. Obviously, a consistent pattern of CPUE values does not occur over time for the entire area. High average CPUE were observed in the years 1975/76 and 1980/81, wheras the lowest CPUE occurred in Subarea 48.3 in 1977/78. The validity of the CPUE index is discussed as an indicator for krill abundance/biomass and caution is expressed in this regard. Depending on the circumstances a CPUE index may seriously under- or overestimate the amount of krill available in a Statistical Subarea. Overall length frequency distributions from commercial fishing operations in general tend to show little interannual variation, because several factors influence the representativeness of krill smaller 35 mm in the catches.

A CCAMLR Ecosystem Monitoring Program (CEMP) was initiated at Bouvet0ya, South Atlantic Ocean, during an expedition to the island from 9 December 1996 to 22 February 1997. A research station was established at the CEMP site, Nyrøysa, on the western coast of the island. Species included in the monitoring program are the Chinstrap Penguin, Macaroni Penguin and Antarctic Fur Seal.
Preliminary results from the first season of CEMP monitoring (parameters A3, A4, A5, A6, A8, A9, C1 and C2) are reported together with results from other CEMP-re1ated work (entanglement of fur seals, and diving behaviour and population changes of penguins and fur seals). The population of Chinstrap Penguins at Nyrøysa has declined sharply since the last count in 1989/90. The population of Macaroni Penguins has shown a more moderate decline, whereas the population of Antarctic Fur Seals has grown dramatically since the last visit.

A CCAMLR Ecosystem Monitoring Program (CEMP) has been initiated by Norway at Bouvetøya, South Atlantic Ocean. A permanent research station was established at the CEMP site, Nyrøysa, on the western coast of the island during the 1996/97 field season. Species included in the monitoring program are the Chinstrap Penguin, Macaroni Penguin and Antarctic Fur Seal. During the first field season (1996/97), monitoring of the following parameters were initiated for the two species of penguins: Breeding population size (A3), Age-specific annual survival and recruitment (A4), Duration of foraging trips (A5), Breeding success (A6), Chick diet (A8) and Breeding chronology (A9). For the Antarctic Fur Seal, the program includes monitoring of Duration of cow foraging/attendance cycles (C1) and Pup growth (C2).