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Number of results: 7
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Abstract

Results of hydroacoustic investigations of krill biomass carried out in the South Shetland Island region between October 1986 and January 1987 are presented. A considerable difference in the krill biomass between Antarctic spring and summer was recorded. Initially observations were conducted close to Elephant Island, in the period just after the retreated of compact ice cover. Krill then aggregated only in swarms, the density of which frequently exceeded 100 t nM-2 . In the region of Polygon I (30—31 October 1986) the total estimated biomass was 26899 t, in the region of Polygon II (6—10 November 1986) it was 25827 t. Investigations were repeated in January 1987 obtaining 112372 t in the Bransfield Strait and 390309 t in the region of Elephant Island. The results are presented in tables and maps.

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Authors and Affiliations

Janusz Kalinowski
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Abstract

Results of hydroacoustic investigations of krill swarms occurring southwest of Elephant Island carried out between 30 October and 5 November 1986, are presented. Krill swarms of the geometric length of 32 m, mean vertical cross section area of 206 m2 , and mean density of 133 g m-3 were recorded and measured. Biomass distribution is presented in maps. The highest density values amounting to 5001 nM-2 were recorded in the eastern part of the survey area, above the slope of Elephant Island's shelf. On the basis of upper and lower limits of the occurrence of given krill swarms, a scheme of their vertical, diurnal distribution was constructed.

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Authors and Affiliations

Janusz Kalinowski
Keywords Antarctic krill stock
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Abstract

Results from the hydro-acoustic studies aiming at evaluation of the Euphausia superba biomass in the Bransfield Strait in March 1981 are presented. These investigations, called conventionally Micro-FIBEX, were carried out on the r/v "Profesor Siedlecki" during 13-16 .March 1981, as continuation of the studies carried out in that region within the scheme of the FIBEX programme in the period of 5-12 March 1981. The abundance of the biomass was estimated at 258 thousand ton, which at the investigated area of about 1755 NM2 gives the mean value of biomass density 142 t/NM2 (41.4 g/m2).

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Authors and Affiliations

Janusz Kalinowski
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Abstract

Stocks of krill in the southern part of the Drake Passage and in the Bransfield Strait were estimated by the hydroacoustic method, during the BIOMASS-FIBEX expedition (Febr.-March 1981). Krill stocks in the Drake Passage and Bransfield Strait were assessed at about 1.2 and 2.3 mln tons, respectively. A map of krill distribution in these regions was prepared. The main krill biomass (66%) was found to occur within the Bransfield Strait which accounts for only 13.7% of the total area under survey.

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Authors and Affiliations

Janusz Kalinowski
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Abstract

On the basis of measurements of the depth of occurrence of 11000 krill aggregations and the biological analyses of these animals and measurements of some environmental factors the diurnal vertical distribution of aggregations is presented against the background of various environmental conditions. Vertical distribution of aggregations is closely related to the feeding rhythm of krill. Active vertical migrations have been recorded at civil twilight. The increasing and decreasing rate of aggregations in those periods is described.

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Authors and Affiliations

Janusz Kalinowski
Zbigniew Witek
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Abstract

During SIBEX the acoustically evaluated amount of krill in the Bransfield Strait and Drake Passage was very low with the mean density 3.24 individuals/m2 and 4.29 individuals/m2 accordingly. Any substantial quantities of krill were found North-West from the Elephant Island and North from the King George Island, where the density of krill exceeded 1000 individuals/m2 (about 100 t/nM2]). The total biomass was estimated at 70590 ton in the Bransfield Strait and at 122470 ton in the Drake Passage, which was many times less than during FIBEX 81, especially in the Bransfield Strait.

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Authors and Affiliations

Janusz Kalinowski
Małgorzata Godlewska
Zygmunt Klusek
Keywords Antarctic krill
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Abstract

The method of target strength measurement adopted for the krill's target strength determination is proposed. The relation between the length of krill's individual and its target strength, obtained at the laboratory conditions, is presented.

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Authors and Affiliations

Janusz Kalinowski
Andrzej Dyka
Leszek Kilian

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