WG-EMM-99

There is a high degree of spatial and temporal variability in the population of Antarctic krill Euphausia superba across the Scotia Sea. Resolution of the spatial component of this variability requires a 'snapshot' of the krill population over the region (eg the CCAMLR B0 survey) whereas temporal changes have been addressed using time-series of samples from the diet of predators. At South Read More
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Dual frequency (38 and 120 kHz) acoustic data from grid surveys in two boxes to the north-west and north-east of South Georgia during December/January 1998/99 were used to estimate mean krill density there. Densities (east = 11.1 g m-2 , west = 12.0 g m-2) were towards the lower end of the range observed over the past two decades, but not abnonnally low, and comprised almost entirely of large Read More
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This paper uses power analysis and bootstrap functions to examine the importance of sample size in detecting differences between two years of fur seal trip duration data. Female foraging trip duration for the first six trips to sea for 1997/98 (n = 30) and 1998/99 (n = 31) at Cape Shirreff, Livingston Island was used to calculate minimum sample sizes necessary to detect differences from year Read More
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A krill density model suggested during WG-EMM at Kochi ( Dy?(1-Rl)-Dy-1?e-M=0) still involved uncertainties of age 1 krill. Present document improves the model by taking the uncertainties in to account, and assuming a reasonable mortality. The model suggested that if we expect the currently accepted values of mortality M (0.8-1.0), the potential proportional recruitment should be larger than Read More
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An index of per capita recruitment (PCR) is proposed such that Ri PCRy–1 = R1y/(1–R1y)eM where R1 is the proportion of age-1 animals sampled in year y and M is the post-recruit mortality rate. The intent of the index is to facilitate investigation of reproductive success and the factors postulated to affect it. The formulation of PCR is based on the assumptions that: 1) post-recruit mortality Read More
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During 1998/99 austral summer the Adélie penguin monitoring program was carried out for the fifth year. The study site was located in the Adélie penguin (Pygoscelis adeliae) colony of Edmonson Point (74°20'56.7" S, 165°08'10.03" E). The aim of this research was to obtain data to contribute to the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) Ecosystem Monitoring Read More
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The CCAMLR Ecosystem Monitoring Program uses indices derived from data on indicator species and the environment collected by standard methods within the three Integrated Study Regions of the Convention Area. Standardised index values are re-calculated each year as new data become available, and trends and anomalies in these data are presented.

In the austral summer of 1995/96, 25 southern elephant seals, Mirounga leonina, were stomach lavaged at Stranger Point, King George Island, South Shetland Islands. Cephalopod remains were present in 72% of the individuals sampled (n=18). Seven species of squid and 3 of octopus were identified. Overall, the squid species Psychroteuthis glacialis was by far the most important prey in terms of Read More
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After almost a ten-year gap in fishing for Champsocephalus gunnari in the area of South Georgia and Shag Rocks, the Russian large-sized trawler ZAKHAR SOROKIN (the MOONZUND-type) attempted a short-time fishing operation in February-March, 1999. Overall, 85 pelagic trawlings yielded 264 tons of C. gunnari. Search for the fish stocks covered all the traditional sites; this allowed observers to Read More
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This paper summarizes the Japanese krill catch data during austral summer through winter of 1997/98 season in the Area 48. The fishing grounds were formed around the South Shetland Islands, west of the Antarctic Peninsula, and around the South Orkneys Islands from mid-December to mid-May. From late May till late June, the operation took place in the north of the South Shetland Islands and Read More
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A discriminant function using simple carapace measurements corretly determined the sex of 87% of male and 89% of female Antarctic krill Euphausia superba. This facilitated the use of sex-specific regression models which increased the accuracy of total length estimates.

We requested data and information for further developing draft standard methods for recording sea-ice cover viewed from a CEMP site (Index F1), local weather at a CEMP site (Index F3) and snow cover at a CEMP site (Index F4). The information at hand was reviewed, and a revised approach to finalising the methodology for calculating these indices is proposed.

Acoustic scattering experiments involving simultaneous acquisition of broadband echoes and video footage from several Antarctic krill were carried out to determine the effect of animal orientation on echo spectral structure. A novel video analysis technique, applied to extract krill angle of orientation corresponding to each insonification, revealed that echo spectra from krill near broadside Read More
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Backscattering measurements of 14 live individual Antarctic krill (Euphausia superb a) were made at a frequency of 120 kHz in a chilled insulated tank at the Long Marine Laboratory in Santa Cruz, CA. Individual animals were suspended in front of the transducers, were only loosely constrained, had substantial freedom to move, and showed more or less random orientation. One thousand echoes were Read More
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The paper introduces several approaches to assessment of hydrological situation in the Atlantic sector of the Southern Ocean (the South-West Atlantic). The analysis of the SST maps suggests that hydrological factors depend on the intensity of two currents, the Antarctic Circumpolar Current and the Falkland current The paper shows correlation between a certain hydrological situation and fishing Read More
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The global abundance of krill is estimated using recent estimates of krill density from acoustic surveys and historical information on the overall range of krill. The biomass estimates fall between 64 and 137 million tonnes - at the low end of values that have been suggested in the past. The differences between our estimates and others can be explained by a number of factors such as: an Read More
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An acoustic survey, designed to study the distribution of shore-breeding, marine predators and their pelagic prey, was carried out in 1986 around the western end of South Georgia. This paper describes how this acoustic data has been used to estimate krill biomass of part of the original survey area as part of an interannual study. The radiating transect design gave increased sampling intensity Read More
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Work undertaken during the intersessional period has enabled better use of the krill fishery data, and a comparison between the three existing indices of fishery-krill-predator overlap used by CCAMLR (catch in the Critical Period and Distance [CPD], Agnew-Phegan index, and Realised Potential Overlap [RPO]) and the Schroeder index. The Agnew-Phegan and Schroeder indices were also compared at Read More
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Fatty acid signature analysis (FASA) makes use of specific fatty acids, as well as entire profiles, to study dietary relationships at different trophic levels. Previously, FASA has been used in marine ecosystems in which diet determination by more direct methods is difficult and sometimes misleading. This study examined fatty acid profiles in milk from two species of pinniped from the Southern Read More
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This study examined three competing hypotheses to explain how lactating Antarctic fur seals (Arctocephalus gazella) respond to changes in the level of resource availability. Antarctic fur seals have episodic bouts of suckling 0-3 days) , alternating with foraging trips (3-10 days). Foraging time budgets varied significantly (P < .001) among 8 consecutive years at Bird Island, South Georgia Read More
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This study examined the relative contribution of environmental variation and the seasonal demands of pup rearing on the foraging behaviour of female Antarctic fur seals Arctocephalus gazella at Bird Island, South Georgia (54° S, 38° W), during 3 austral summers (1994 to 1996). Time-depth recorders measured the diving behaviour of 72 individuals during a total of 385 foraging trips totalling Read More
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Archival data loggers were used to collect information about depth, swimming speed, and heart rate in 23 free-ranging antarctic fur seals. Deployments averaged 9.6 ± 5.6 days (SD) and totaled 191 days of recording. Heart rate averaged 108.7 ± 17.7 beats/min (SD) but varied from 83 to 145 beats/min among animals. Morphometrics explained most variations in heart rate among animals. These Read More
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Refinements have been made to the multiple-frequency method that was recently developed to improve the accuracy and precision of in-situ target strength (TS) measurements using split-beam echosounders (Demer et al., J. Acoust. Soc. Am. 105(4) 2359:2376 (1999)]. The multiple-frequency method improves the rejection of unresolvable and constructively interfering target multiples by combining Read More
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The influence of two sampling protocols on diet determination of two marine predators, the Gentoo penguin Pygoscelis papua and Antarctic fur seal Arctocephalus gazella, was investigated. The collection of diet samples on three occasions over a two week period was compared with collecting all samples during a single session, as current CEMP monitoring protocols recommend. Some differences in Read More
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The diet of the gentoo penguin Pygoscelis papua was investigated during three different autumn periods at Laurie Island, South Orkney Islands (60°46’S, 44º42’W), Antarctica. Stomach contents of migrant adults were sampled during 1993, 1995 and 1996. Fish were the most important prey by mass in 1995 (81.1%) and 1996 (60.5%) whereas crustaceans predominated in 1993 (70% by mass). Euphausia Read More
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This study examined the feasibility of using time depth recorders (TDRs) to measure light levels experienced by a diving marine mammal. TDRs were deployed on 10 female Antarctic fur seals (Arctocephalus gazella) at Bird Island, South Georgia (54° 00' S 38° 02' W) in the 1994/5 austral summer. Depth and light measurements were made during 11 foraging trips which lasted on average (± SE) 7.1 ± 0 Read More
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The current long-term estimates of mean recruitment rates suggest that the population is unsustainable, as they are too low to maintain the estimated mortality rate. The variable annual estimates of recruitment to the population can be used to model in detail interannual variation in the population dynamics of krill and estimate the expected mortality rates. A number of models of the Read More
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Antarctic and sub-Antarctic seabirds, marine mammals, and human fisheries concentrate their foraging efforts on a single species, Antarctic krill (Euphausia superba). Because these predators may have a significant effect on krill abundance, we estimated the energy and prey requirements of Adelie (Pygoscelis adeliae), chinstrap (Pygoscelis antarctica), and gentoo (Pygoscelis papua) penguins and Read More
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This paper describes the diet and foraging behaviour of Ad6lie penguins at B6chervaise Island during 1998-99, a season of high chick mortality. One thousand nests perished in the three weeks following first hatch, when the chicks were very small. A total of 802 chicks reached crèche age from 1880 nests compared to previous "good" seasons in which between 1200 and 1800 chicks crèched on the Read More
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We irradiated captive juvenile Euphausia superba in the laboratory with lower than spring surface levels of ultraviolet-B, ultraviolet-A and photosynthetically active radiation, in order to examine their response in terms of mortality and generalised activity. Levels of photosynthetically active radiation 3–5 times below surface irradiance caused krill to die within a week, while animals in Read More
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Variability in the Southern Ocean is frequently reflected in changes in the abundance of Antarctic krill Euphausia superba and subsequent effects on dependent predators. However, the nature and consequences of changes in krill population dynamics that accompany l1uctuations in its abundance are essentially unknown. A conceptual model, developed froll1 quantitative measures of krill length ill Read More
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An assessment of the environmental processes influencing variability in the recruitment and density of Antarctic krill (Euphausia superba) is important, as variability in krill stocks affects the Antarctic marine ecosystem as a whole. We have assessed variability in krill recruitment and density with hypothesized environmental factors, including strength of westerly winds (westerlies) Read More
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The distribution of whales and krill in two survey boxes north of South Georgia was examined by comparing sightings and underway acoustic data collected as part of a multidisciplinary research cruise during January/February 1998. A total of 222 cetaceans of 10 species was recorded with southern right whale (Eubalaena glacialis) and humpback whale (Megaptera novaeangliae) the two most frequent Read More
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To assess large whale stocks following the cessation of land-based South Georgia whaling in 1965, we report three independent sighting databases: a cruise in 1997, observations from Bird Island (NW of South Georgia) between 1979 and 1998, and mariner sightings between 1992 and 1997. All species were rare, with southern right whale sightings being the most common event. Two right whales Read More
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The necessity of synoptic survey covering the South Sandwich Islands that are an integral part of Area 48 is discussed. It is shown that in this case there shall be obtained for the first time for the recent twenty years the material which allows to have an idea of krill simultaneous distribution over the whole water area of Subareas 48.1-48.4 covering a vast zone of krill drift and that of Read More
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The antioxidant defences in aerobic organisms represent the detoxification pathway against toxicity of reactive oxygen species (ROS). These highly reactive molecules are normally produced during the 4-electrons reduction of molecular oxygen to water coupled with oxidative phosphorylation and during the activity of several enzymatic systems which produce ROS as intermediates. If the antioxidant Read More
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Diet studies are a key component of the CCAMLR predator monitoring program as they provide direct assessments of the prey types and amounts of import to predators, which, in turn, are hypothesized to influence variability in related parameters such as breeding success, foraging trip durations and chick fledging weights. Given the importance and interdependence of diet studies to monitoring Read More
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This background paper consists of the agenda and information for the Second International Symposium on Krill which has been partially sponsored by CCAMLR. The symposium will be held at the University of California, Santa Cruz, from 23–27 August 1999. Further information can be found on the website: http://www2.ucsc.edu/people/msmangel/Krill Read More
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We update in this paper the previously reported model for the Antarctic fur seal Arctocephalus gazella population breeding at Cape Shirreff and San Telmo Islets (SSSI No.32), Livingston Island, South Shetland, Antarctica. We also discuss the current reliability of the model and related population parameters to an environmental index (the Southern Ocean Oscillation Index - SOI).
Two fur Read More
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The underwater vessel noise levels perceived by the echosounder EK-500 transducers of three Russian research vessels have been presented. These data have been compared to the estimate of the underwater noise level, produced by the Icelandic R/V B.Saemundsson..
Underwater noise level perceived by the echosounder transducer versus its operation frequency and vessel speed has been analyzed Read More
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