WG-EMM-96

Using stomach lavage samples from macaroni penguins (Eudyptes chrysolophus Brandt) breeding at Bird Island, South Georgia and concurrent net samples caught within the penguin foraging range, we examined the potential selection of different length and maturity stages of Antarctic krill (Euphausia superb a Dana). Using Monte Carlo randomised simulation techniques we also determined the Read More
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This paper was requested by WG-EMM in 1995 (SC-CAMLR-XIV, Annex 4, paragraph 6.49). In the early years of development of the ecosystem monitoring program sea ice data, especially derived from satellite images, was recognised as an important source of information for interpreting changes in monitored predator parameters. Standard methods for collection of environmental parameters were agreed in Read More
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1. Although the development of fisheries for krill in the southern oceans has prompted considerable work on the indirect effects of fisheries on krill predators, to date all work has focused on population level effects. Here, we present for. the first time a model at the level of the foraging trip for the effects of a fishery on krill predators, using the Adelie penguin (Pygoscelis adeliae) as Read More
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The purpose of this paper is to synthesize information on the energetics and food requirements of krill predators that may be in the most direct competition with the krill fishery. These krill predators are the Adélie (Pygoscelis adeliae), chinstrap (Pygoscelis antarctica), gentoo (Pygoscelis papua), and macaroni (Eudyptes chrysolophus) penguins and the crabeater (Lobodon carcinophagus) and Read More
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The CCAMLR Ecosystem Monitoring Programme has two aims: to detect changes in critical components of the antarctic ecosystem, and to distinguish between changes due to the harvesting of commercial species and changes due to environmental variability. Data from Seal Island are used to construct a multivariate model which relates chinstrap penguin breeding success, krill abundance and sea ice Read More
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Acoustic surveys designed to assess krill abundance are costly in time and money, so the opportunity was taken in 1992 to produce a krill biomass estimate as a by-product of a fish stock-assessment surveyin CCAMLR Subarea 48.3. Acoustic transects were run between trawl stations using a sounder operating at 38 kHz and 120 kHz. The results have been analysed for all straight sections of track Read More
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A major biological/physical survey of the waters off East Antarctica was carried out between January and April 1996. The focus was on the distribution and abundance of Antarctic krill in CCAMLR Statistical Area 58.4.1 but in addition, measurements were also made on a whole suite of oceanographic and biological variables over the entire survey area. This paper summarises the range of variables Read More
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Analysis of seasonal sea ice cover of a 1,250,000 km2 area off the northwestern side of the Antarctic Peninsula indicates that four "ice events" have occurred during the last 1 7 years. The most recent event was first apparent in 1994 and continues through the latest data available. Variability between ice events in seasonal timing, areal extent, seasonal duration and persistence over multiple Read More
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Predator data and exploratory fishing in the Scotia Sea have revealed the presence of cephalopod stocks in the Antarctic Polar Frontal Zone (PFZ). This is a vast, remote region where large epipelagic cephalopods aggregate into highly mobile schools making them difficult to locate and sample. We used satellite tagged predators and shipboard acoustics for coarse and fine scale location of Read More
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There is a growing body of evidence that the climate of the Antarctic Peninsula region has been warming over the past 40 years with an associated decreased frequency of winters with extensive sea-ice development. These trends potentially will have a major impact on the structure and function of the Antarctic marine ecosystem. In the Antarctic Peninsula region winter sea-ice coverage is a major Read More
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Diets of diurnal and overnight foraging chinstrap penguins (Pygoscelis antarctica) breeding at Seal Island during chick-brooding period of 1988/89, 1989/90, 1993/94 and 1994/59 were analyzed. Diet mass estimated from digested and intact stomach contents indicates that krill were predominant in their diets but fish constituted 0-1 % and 14-45 % of the diet of diurnal and overnight foragers Read More
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At Seal Island breeding predators which incorporated an overnight period into their foraging trip such as Antarctic fur seals (Arctocephalus gazella) and overnight foraging chinstrap penguins (Pygoscelis antarctica) went beyond the inshore region and foraged in the slope/offshore region, even though the slope/offshore region was less abundant with krill and more remote from their breeding Read More
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CPUE and Recruitment indices during 1980 to 1995 were calculated based on the log book data from commercial krill trawlers. Long-term variation of monthly CPUE was shown but this trend might be the result of the alternation of operational strategy in relation to the product quality. Recruitment indices in this paper agreed with Sigel and Loeb (1995) in genaral trend, however, some Read More
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Monthly CPUEs during winter operation of Japanese krill trawlers around South Georgia were calculated. The range of CPUE values in 1991 season (poor year of krill) was comparable to the range of summer operation around Elephant Island and Livingston Island. Vertical distribution presumed from net towing depth. Net tow depth data implied that overall krill distribution in the the winter season Read More
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This paper summarizes Japanese krill catch data during austral summer in 1994/95 season. Main fishing grounds were persistently formed in the north of Livingston Island throughout the season (except April), and around Elephant Island during April to May. CPUEs in the fishing to the north of Livingston Island were relatively stable through out the season, however, it was highly variable around Read More
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The distribution of kri!! harvesting effort and associated catch rates has previously only been available to the scientific community in the form of sub-area or fine-scale(0.5 ° latitude by 1 ° longitude) recorded statistics. Earlier analyses of these data have shown this was a shelf-break fishery over much of the Scotia Sea. Although these statistics give a general idea of where the fishery Read More
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The diet of the Cape petrel Daption capense was investigated at Laurie Island, South Orkney Islands (60°46'S, 44°42'W), Antarctica, over the period January-February 1996. Stomach contents of adults and regurgitate of chicks were sampled during the post-hatching period. The analysis showed that during the whole sampling period Antarctic krill and fish represented the predominant preys in terms Read More
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Results from two acoustic and net surveys conducted in the vicinity of Elephant Island during the 1996 austral summer indicate very good krill recruitment from spawning in 1994/5. Areas of high krill density were mapped north of King George and Elephant Islands where water depth was greater than 200m. One-year old juvenile krill numerically dominated catches during the first survey in January Read More
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To investigate the role of sea ice cover on penguin populations we used principal component analysis to compare population variables of Adélie (Pygoscelis adeliae) and chinstrap (Pygoscelis antarctica) penguins breeding on Signy Island, South Orkney Islands with local (from direct observations) and regional (from remote sensing data) sea ice variables. Throughout the study period, the Adélie Read More
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It has been suggested that modes of vibration of solid elastic spheres, such as those used in the calibration of echo sounder systems, can be affected by the manner of suspension. This hypothesis is investigated in the context of reported experimental calibration trials with the SIMRAD EK500/120-kHz echo sounder. In these, as many as four different spheres were used: 23- and 30.05- mm-diameter Read More
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The methods and preliminary data on evaluation of krill transfer factors results in subarea 48.2 in the period of 19.02-07.03.96 are presented. The polygon of 80 x 240 miles was situated in interaction zone of the two circulating systems of the climatic scale: Antarctic Circumpolar Current and Weddell Sea waters. The experiment was carried out in two stages: evaluation of krill transport Read More
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On the ground of trawling of Ukrainian vessels made near the South Georgia from 16 June till 15 August 1995 peculiarities of krill distribution, their characteristics including time stability (tolerance), are examined, calculations of biomass and krill commercial concentrations values are given.
Interannual changes in some indices of krill fishing Resources in this subarea from 1985 till Read More
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The krill-predator modelling calculations of Thomson and Butterworth (1995) are extended to take account of a number of the suggestions made at the 1995 meeting of the CCAMLR Working Group on Ecosystem Monitoring and Management. The resilience of the Antarctic fur seal population to krill harvesting is found to be strongly dependent on the estimate of the maximum annual growth rate (R) which Read More
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In this document we inform on the results of six years monitoring changes in the diet of the Blue-eyed Shag Phalacrocorax atriceps as reflected by the analysis of regurgitated pellets collected at two localities of the South Shetland Islands. The comments are mainly focused on Gobionotothen gibberifrons and Notothenia rossii, species of particular interest for CCAMLR. Notothenia rossii Read More
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This paper presents data on the distribution of E. superba in the Atlantic sector and adjacent waters with an emphasis on subregions lying beyond the current fishing grounds of the Scotia Sea. In a number of subregions on the periphery of the Weddell Gyre (both to the north and south), as well as in the coastal waters of the Antarctic continent, the formation of krill aggregations is variable Read More
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Hatching season and larval growth of Pleuragramma antacticum in the water off Antarctic Peninsula were determined by the examination of growth increments in otoliths. The samples were collected by Bongo plankton net or MOCNESS from December 1993 through January 1994. P. antacticum was predominated (54 inds. out of 77 fish larvae) in ichthyoplankton samples, and occurred mainly in cold water of Read More
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There are presented some results of atmospheric circulation features evaluation over Antarctic Sector of Atlantic, thermochaline conditions and surface geostrophic transfers.
There are obtained daily indeses of atmospheric circulation for the period February-March 1996, calculated average values for ten-days periods and for month.
There are calculated cyclogenesis intensity Read More
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Four indices of prey availability are calculated for prey surveys conducted in the vicinity of the Seal Island CEMP site during the austral summers of 1990-96. The indices are measures of average prey density, depth, distance from Seal Island, and persistence over time. Acoustic data from two AMLR surveys each year were sub-sampled to include the foraging range of predators breeding at Seal Read More
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Mackerel icefish (Champsocephalus gunnari) are widespread on the South Georgia (54 degS, 36 deg W) shelf. Analysis of results on condition index indicated a strong inter-annual variation. High condition indices, indicative of good feeding conditions, were present when krill were abundant in the region. Years when krill were scarce and condition index was consequently low, were consistent with Read More
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Acoustic surveys were carried out in January 1996 within two 100 x 80 km boxes located over the shelf-break to the north-east and north-west of South Georgia. Surveys were conducted from RRS James Clark Ross using a Simrad EK500 echo-sounder operating at 38, 120 and 200 kHz. These surveys were the first in a new five-year British Antarctic Survey programme initiated in part to monitor inter- Read More
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Samples of Antarctic krill collected from six seabird species and Antarctic fur seal during February 1986 at South Georgia were compared to krill from scientific nets fished in the area at the same time. The length-frequency distribution of krill was broadly similar between predators and nets although the krill taken by diving species formed a homogeneous group which showed significant Read More
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Krill distribution and density are reviewed for the Elephant Island area with regard to the representativeness of the study area (60° - 62°30'S and 53° - 57°30 'W) for the recruitment and density indices. Recruitment indices were re-calculated applying the delta distribution approach introduced by de la Mare (1994a). The high interannual variability of krill recruitment is confirmed by the Read More
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Horizontal and vertical velocities of fish schools were measured using an acoustic Doppler current profiler (ADCP). To determine three orthogonal velocity vectors (east, north, and vertical), it was required that the four ADCP beams simultaneously insonified a fish school, in the same depth bin. Velocity vectors which satisfied these conditions were extracted from individual ping velocity Read More
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A time-dependent, size-structured, bioenergetically-based model was developed to examine the growth dynamics of Antarctic krill, Euphausia superba. A system of coupled, ordinary differential equations was developed to describe the growth of krill between 2 and 60 mm. The metabolic processes included in the model were ingestion, assimilation efficiency, a baseline respiration. respiratory Read More
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In the paper the attempt was made to compare selective features of several midwater krill trawls within the frame of krill density precise estimates provision problem in echo-surveys. The results of fishing one krill aggregation with two types of trawls (PT 72/308 commercial trawl and Isaacs-Kidd research trawl IKTM) are presented. Selectivity differences of those trawls resulted in Read More
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Investigations on by-catch of fishes captured during krill fishing by F/V Chiyo Maru No. 3 were made from 3 February to 6 March, 1996 to the north of the South Shetland Islands. Among 147 hauls examined, a total of 99 specimens belonging to 5 families and 14 species were captured as by-catch in 41 hauls. Notothenioid juveniles were found in 30 hauls carried out in waters with a depth of 87- Read More
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The ninth survey of the Japanese Whale Research Programme Under Special Permit in the Antarctic (JARPA) was carried out in the Antarctic Area IV (south of 60° S between 70°E and 130°E) and eastern part of Area In (south of 60° S between 35°E and 70°E). The survey was conducted for 118 days, from 26 November 1995 to 22 March 1996. The research fleet was composed of a research base vessel, Read More
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In January-March 1996 a hydroacoustic survey for Antarctic krill was conducted in CCAMLR Division 58.4.1 for the purposes of estimating overall biomass (B0). The krill biomass in the area surveyed (873,000 km2) was estimated to be 6.67 million tonnes with a CV of 27%. Krill were more abundant in the west of the survey area 800-1200E than in the 120°-150°E region. The majority of the krill Read More
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In the period from 24 February to 7 March 1996 in the cruise of RV "Atlantida" acoustic assessment of krill biomass and distribution was carried out in study area restricted with 59° 10' S - 60°30' S and 42 °00' W - 50°00 'w within Subarea 48.2. The study area of 19.200 sq.mi1es was located in the zone of two circulation systems of climatic scale interaction: Antarctic Circumpolar Current and Read More
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Adelie penguins are long-lived, highly philopatric seabirds that dominate the bird biomass of the Western Antarctic Peninsula region, and serve as focal animals for our Long Term Ecological Research (LTER) study of the effects of environmental variability on animal populations in the Antarctic marine ecosystem. The major physical factors affecting the breeding success, distribution and Read More
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The fish component of the diet of black-browed and grey-headed albatrosses at South Georgia was investigated by intercepting 155 meals from adults arriving to feed chicks during February 1986 and 1994. Fish represented 30% and 72% by mass of the diet of black-browed albatrosses and 14% and 60% by mass of the diet of grey-headed albatrosses in 1986 and 1994 respectively. We determined the Read More
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This paper presents a summary of the foraging locations of the Ad6lie penguin at 7 widely spaced locations along the coast of Eastern Antarctica between 55°E near Enderby Land and 175°E in the Ross Sea region. Birds feeding chicks regularly travel 100-120km offshore to the continental shelf and return with krill. The pattern of foraging is similar between sites. The potential for overlap with Read More
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Twenty eight stomach contents of the South Polar Skua Catharacta maccormicki were collected throughout the breeding season at Half-moon Island, South Shetland Islands, Antarctica. The analysis of the samples indicated that fish were the most frequent prey (100%) and also predominated in mass (98%) and that their importance remained constant all along the study period. Eight fish species were Read More
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By using time-depth recorders to measure diving activity and the doubly-labelled water method to determine energy expenditure, the relationship between foraging behaviour and energy expenditure was investigated in nine Antarctic fur seal females rearing pups. At-sea metablic rate (MR) (mean of 6.34 ± 0.4 W • kg–1; 4.6 times predicted BMR) was positively correlated to foraging trip duration ( Read More
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Calibration of echo sounders for fish stock assessment are commonly performed using the standard sphere method (Johannesson and Mitson, 1983; Simmonds et al., 1984). To determine the accuracy of the method, direct measurements of target strength (TS) were made of three standard spheres (Copper (Cu) - 23.0 mm and tungsten carbide (WC) - 33.0 mm and 38.1 mm). At the best case range of 5 m, the Read More
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