WG-EMM-97

Data on Antarctic petrel Thalassoica antarctica population and demography monitoring at Svarthamaren, Dronning Maud Land from five field seasons between 1991/92 and 1996/97 is presented. The results of the population monitoring show that the number of pairs with chick or egg varied between 55,387-178,240 (mean 119,000). Assuming that about 10 % of the colony is situated in inaccessible parts Read More
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Target strength measurements of free swimming krill at 120kHz were made using a single beam monostatic system in a 10 m3 laboratory tank. Krill (grouped according to length classes) swam freely in the tank triggering the data acquisition system when generating a back scattered signal larger than a threshold, determined by the system noise level. Dorsal and ventral target strength estimates Read More
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The results of acoustic surveys, especially in low signal-to-noise regimes, are sensitive to the method used to exclude the contribution of background noise from the acoustic data. The use of thresholds to reject weak signals during data collection is inappropriate because the noise contribution to the above-threshold-signal cannot later be removed in post processing. The only solution is to Read More
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Krill (Euphausia superba) provide a direct link between primary producers and higher trophic levels in the Antarctic marine food web. The pelagic tunicate Salpa thompsoni can also be important during spring and summer through the formation of extensive and dense blooms. Although salps are not a major dietary item for Antarctic vertebrate predators, their blooms can affect adult krill Read More
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Scientific observations on fishes incidentally caught during krill fisheries by F/V Niitaka Maru were made from 1 to 23 February, 1997 to the north of the South Shetland Islands. Among 80 hauls examined, a total of 61 specimens belonging to 4 families and 7 species, Electrona antarctica (50 specimens), Electrona carlsbergi (4), Protomyctophum tenisoni (1), Gymnoscopelus opisthopterus (1), Read More
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Thomson and Butterworth (1996) developed a krill-predator model and applied this to an Antarctic fur seal dataset. These calculations are extended here. The level of krill fishing intensity required to halve the fur seal population (γhalf) is between 0.08 and 0.09, slightly lower than that estimated previously. Tests of the estimation procedure indicate that γhalf estimates are likely to be Read More
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Polynyas accelerate oceanic and atmospheric processes. We additionally think polynyas influence biological activity. We pursued daily transition of coastal polynyas in the Antarctic Peninsula area from 1978 through 1995 using images of sea ice concentrations by the satellite microwave observations. A typical polynya existed off the tip of the Peninsula in 1987 and 1991. In the such years, sea Read More
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The changing nature of marine fisheries requires management approaches that recognize and include ecosystem and environmental effects. Therefore, we review some examples of exploited fishery stocks in which environmental control is a major contributor to structuring the abundance and distribution of the stock. Four examples, ranging from Antarctic krill to oysters, are given that clearly Read More
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The transport of secondary production in the Southern Ocean food-web was investigated using a combination of physical model data and ship based biological data. The physical current velocity dataset was from FRAM and was used to derive a mean velocity field for the upper 250m of the water column. These have been combined with estimates of krill density and standing stocks to consider the flux Read More
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The foraging behaviour of Adélie Penguins Pygoscelis adeliae was studied simultaneously at Shirley Island (SI) near Casey Station and at Petrel Island (PI) at Dumont D'Urville during the 1995/96 breeding season. The study took place in conjunction with a ship-based krill survey in the CCAMLR Division 58.4.1 (south of 55 °S, 80 - 150 ° E) to determine the extent of overlap between penguin Read More
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The accuracy of correction factors estimated to compensate the digestion and loss through the gastrointestinal tract of the otoliths of fish represented in pellets of the Antarctic Shag Phalacrocorax bransfieldensis was tested at two localities of the South Shetland Islands. F or such purpose, the results from the analysis of 226 and 115 pellets collected at Harmony Point and at Duthoit Point Read More
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The diet of juvenile and non-breeding male Antarctic fur seals Arctocephalus gazella was investigated at Harmony Point, Nelson Island, South Shetland Islands, by the analysis of 18 and 33 scats collected during the 1995/96 and 1996/97 summer seasons respectively. Overall, fish were the most frequent prey (74,5%) and predominated by mass (54,4%), whereas krill did by number (94.2%). This Read More
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The diet of the Antarctic petrel Thalassoica antarctica was studied during two years at Svarthamaren, an inland colony situated in Dronning Maud Land, Antarctica and in the pack-ice outside Svarthamaren. The analyses showed that the most important food (wet weight) at Svarthamaren was Crustaceans (68%), followed by fish (29%) and squid (3%), whereas individuals collected in the pack ice took Read More
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A study on the breeding biology and diet of Pintado Petrels Daption capense was conducted at Nyrøysa, Bouvetøya, South Atlantic, from December 1996 to February 1997. Overall breeding success for the total 300 pairs of breeding Pintado Petrels at Nyrøysa was 59 %. Three study colonies were marked out and monitored intensively; in one colony overall breeding success was only 4 % owing to Read More
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Acoustic surveys in the vicinity of the sub-Antarctic island of South Georgia revealed the existence of a number of horizontally extensive yet vertically discrete scattering layers in the upper 250 m of the water column. These layers were fished with a LonghurstHardy plankton recorder (LHPR) and a multiple-opening 8 m2 rectangular mid-water trawl (RMT8). Analysis of catches suggested that each Read More
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The paper, based on the results of italian expeditions to the Ross Sea (December 1989 - Januar 1990 and November - December 1994), presents how is spatial and temporal distribution of krill biomass and what is its value. The hydroacoustic observations were done in the time when investigated area was pratically covered by pack ice (November - mid December) or immediately after ice had receded ( Read More
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Accurate estimation of krill biomass by acoustic techniques is dependant upon a number of factors including, fundamentally, accurate echo-sounder calibration. The Simrad EK500 scientific echo-sounder used aboard RRS James Clark Ross is regularly calibrated at South Georgia before and after krill surveys, and exhibits acceptable temporal stability in system gain settings. Between Antarctic Read More
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The research performed was aimed at assessment of fishing fleet impact upon krill population during the months (December-March), being critical to dependent species. The results of fishing intensity estimation are presented on the basis of haul to haul commercial statistics for Russian fleet (data of 2900 trawlings are used) in the South Orkneys area during December 1989 - March 1990. In the Read More
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The results of analysis of haul by haul catch statistics of Soviet commercial fleet during 1989/90 season (totally 3614 hauls for the period from 1.11.1989 to 12.06.1990 are presented. Actually during the whole season fishing vessels worked in one fishing ground off the north-western edge of Coronation Island. Incidentally, CPUE shows regular intraseasonal variations from minimum (3.2 t/hour) Read More
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The results of hydroacoustic survey of krill biomass assessment in Subarea 48.2 adjacent to Coronation Island, carried out in February-March 1996 in Russian RN "ATLANTNIRO" are presented. Taking in account close relation of krill and oceanographic structure of waters and currents, hydrorological conditions during surveys are also discussed in the paper. Average weighed density of krill in the Read More
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Stratified random acoustic surveys, each comprising 10 parallel transects, were conducted within two 80 x 100 km areas over the shelf-break to the north-east and north-west of South Georgia during December/January 1996/97. Netting suggested that the mean lengths of krill within the eastern and western survey boxes were 36.1 mm and 45.4 mm respectively. These lengths were used to derive box- Read More
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Between 1980 and 1997 British Antarctic Survey carried out 11 cruises in the region of South Georgia. Here we summarize the length-frequency distributions of krill caught on each of these cruises and look particularly at differences between krill taken from the eastern and western ends of the island. Cluster analysis revealed that the length-frequency distributions could be grouped into 5 main Read More
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Acoustic surveys to estimate krill biomass require that sound backscattered by krill be identified and distinguished from all other types of backscatter. Traditionally this has been achieved by sampling characteristic types of acoustic target with nets. More recently partitioning of backscatter into species groups has been attempted using differences in echo strength at two acoustic Read More
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Two Monte Carlo simulation models are currently available to CCAMLR for estimating krill yields according to decision rules that relate spawning stock status to the median unexploited spawning biomass, SB0. The first model has been developed specifically for krill, the krill yield model, while the second is a generalised yield model. The decision rules relate to the effects of a specified long Read More
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The 1997 Workshop on International Coordination was convened by Suam Kim (Korea) at 0900 on 14 July 1997 at the Southwest Fisheries Science Center, La Jolla, California. In attendance were Sung-Ho Kang (Korea), Hyungmoh Yih (Korea), Mikio Naganobu (Japan), So Kawaguchi (Japan), Volker Siegel (Germany), Anthony Amos (USA), David Demer (USA), Christopher Hewes (USA), Roger Hewitt (USA), Osmund Read More
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This work presents the initial comparative analysis of acoustic and net haul krill density estimates for the RMT 8 oblique (0 to 200m depth) trawls conducted during January-March 1996 as part of a hydroacoustic biomass survey for Antarctic krill in CCAMLR Division 58.4.1.
The acoustic krill density estimates were consistantly larger than the net estimates, otherwise no relationship was Read More
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The Patagonian toothfish, Dissostichus eleginoides, has been reported as prey of Elephant seals in the Heard Island region. A question was raised at SC-CAMLR-XV concerning what affect the fishery for toothfish in Division 58.5.2 might have on the abundance of the age classes of toothfish preyed on by these seals. This paper provides an updated analysis of the age of toothfish taken by Elephant Read More
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Data from individual trawls carried out by vessels operating in the krill fishery at South Georgia are examined and a range of descriptive measurements reflecting the operation of the fishery are produced. The measurements indicate that the krill fishery at South Georgia is geographically focussed, operating in a limited area along the shelf edge on the northern coast of the island. Each day a Read More
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The Polar Front (PF) forms the southern boundary to the Polar Frontal Zone (PFZ) along the northern edge of the Antarctic Circumpolar Current (ACC). In a number of areas the position of the PF (and thus the PFZ) is known to be influenced by topographic steering, while local bathymetry has also been implicated in the movement and retention of various associated mesoscale features. In this paper Read More
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For three austral spring and summer field seasons, 1994-97, the Antarctic Site Inventory project has collected data and information about Antarctic Peninsula visitor sites. These data and information are intended to assist in establishing baselines for: future environmental assessments under the soon-to-be-effective Antarctic Environmental Protocol; designing future monitoring programmes to Read More
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Data on salp by-catch and green krill were analyzed based on Logbook data of Japanese krill trawlers. Inter-annual and seasonal variability of the timing, duration and strength of salp bloom were indicated. Salp by-catch and occurrence of green krill seemed to show reverse correlation, implying the competition for phytoplankton between krill and salps.

This paper summarizes Japanese krill catch data during austral summer in 1995/96 season. Main fishing grounds were persistently formed in the north of Livingston Island throughout the season. CPUE in December was high but from January through June CPUE was comparable to the value of Livingston area in the previous fishing season. From January through early May, modal size of krill differed Read More
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Proportional recruit indices and CPUE in Subarea 48.1 (Antarctic Peninsula region) from 1980 through 1996 were calculated based on the log book data from Japanese commercial krill trawlers. Proportional recruits calculated from fisheries data showed similarity with those from scientific data (Siegel et al., 1997), and showed close relationship to sea ice indices. CPUE (catch/towing volume) in Read More
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Results from two net surveys in the Elephant Island area during January-March indicated moderate krill abundance and lower recruitment success of the 1995/96 year class relative to that of 1994/95. These occurred after a relatively early 1996 spawning season that theoretically should have promoted good krill recruitment. However winter 1996 was characterized by slightly below average winter Read More
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Data from 1995-1997 US Antarctic Marine Living Resources (AMLR) Program surveys in the Elephant Island area are examined to determine the level of sampling effort required to adequately assess the (1) abundance and demographic structure of Antarctic krill and (2) relative abundance and interspecific relations of krill, salps and other macrozooplankton taxa in the Elephant Island area during Read More
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The Elephant Island long-term data set was updated for krill density and proportional recruitment. Krill biomass (from net sampling surveys) and absolute recruitment are introduced as additional indices for this time series. New survey results of the past two seasons indicate a very successful 1994/95 and an average 1995/96 krill year-class (below average for proportional recruitment, average Read More
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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, Read More
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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 Read More
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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 Read More
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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 Read More
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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.
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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 Read More
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As an indicator of body fat condition, interannual variability in girth of minke whales (Balaenoptera acutorostrata) was analyzed in relation to sea-ice extent, stomach-content mass and distribution of minke whales in Antarctic Areas IV (70° -130° E) and V (130° E-170°W) from 1989/90 to 1994/95. Of the six years included in the study, two were categorized as years of poor body fat condition, Read More
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The consumption of Antarctic krill (Euphausia superba) by the southern minke whale (Balaenoptera acutorostrata) in Areas IV and V of the Antarctic was estimated from diurnal change in the forestomach content mass, standard metabolism and the body mass increase methods based on JARPA (the Japanese Whale Research Program Under Special Permit in the Antarctic) data. Estimates of the daily food Read More
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During December 1996 the Elephant Island standard grid was surveyed for krill and salps. Krill and salps were present at almost all of the stations, other epipelagic zooplankton species were relatively scarce. Maximum krill density exceeded 7350 juvenile krill per 1000 m3. In general krill density was much higher than in previous years. The krill stock was dominated by length classes around 35 Read More
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The diets of six of the main seabird species (two petrels, two albatrosses, two penguins) breeding at Bird Island, South Georgia were studied simultaneously during the chick-rearing period in 1986. For five species, Antarctic krill Euphausia superba was the main food (39-98% by mass); grey-headed albatrosses took mainly the ommastrephids squid Martialia hyadesi (71 %) and only 16% krill. The Read More
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Fatty acid signature analysis is based on the conservation and unique signatures of fatty acids in the marine food chain and it may be useful in determining the composition of seal diets or in detecting changes in diets. We apply fatty acid signature analysis to milks collected from Antarctic fur seals at South Georgia during the perinatal period (n= 19) and subsequently during early (n=11), Read More
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The diet of the Antarctic Prion Pachyptila desolata was examined using food samples regurgitated by adult birds during five breeding seasons at Bird Island, South Georgia. In all years the diet was mainly crustaceans, with a small proportion of myctophid fish and trace amounts of cephalopods. Antarctic krill Euphausia superba was the dominant prey item in three years and was replaced by Read More
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The body composition, milk consumption, and growth efficiency of Antarctic fur seal (Arctocephalus gazella) pups were measured over three consecutive lactation periods (1990-1992) at Bird Island, South Georgia. The body composition of pups differed between the sexes; whereas for any given age females were lighter than males, they had proportionately higher body lipid reserves than males. Milk Read More
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The diet of the diving petrels Pelecanoides georgicus and P. urinatrix was studied during 1986 (P. georgicus) and 1987 (both species) by lavaging adults as they returned to feed chicks on Bird Island, South Georgia. The diet of both species was dominated by crustaceans. in particular euphausiids (mainly Euphausia superba and some ThysCll1oessa), which contributed 47-76% of the biomass of Read More
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The diet of king penguins, Aptenodytes patagonicus, rearing chicks was studied during three consecutive austral winters (1990, 1991 and 1992) at Crozet Islands. The mean stomach content mass of the 47 samples was 503 g. Percentages of wet and reconstituted masses showed that both fishes (66 and 36%, respectively) and squid (34 and 64%) are important components of the winter diet. Juveniles of Read More
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Seasonally breeding predators, which are limited in the. time available for provisioning young at a central location, and by the fasting abilities of the young, are likely to maximize energy delivery to the young by maximizing the rate of energy delivery averaged over the whole period of investment. Reduction in food availability or increased foraging costs will alter the optimal behavior of Read More
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Based on historic data as provided by the World Ocean Atlas 1994, the general climatic background for temperature, salinity and silicate is given for the area between the Fa1kland (Malvinas) Islands and the Antarctic Peninsula Region. A data set sampled during December 1996 in the Elephant Island Plateau Region by RV POLARSTERN, is compared to the climatic background data, and to more recent Read More
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