Distribution and life history of krill from the Barents Sea

Abstract

Krill from the Barents Sea were studied on six cruises from 1985 to 1989. Thysanoessa inermis and T. longicaudata were the dominant species, while T. raschii and Meganyctiphanes norvegica were rarer in the studied areas. The two dominant species T. inermis and T. longicaudata are mainly found in the Atlantic. Water and they do not to a large extent penetrate into Arctic water masses in the northern Barents Sea. M. norvegica is a more strict boreal species that does not occur as extensively in the Barents Sea as do the Thysanoessa species. The mean population abundance ranged from 1 to 61 individuals m?2 for T. inermis and from 2 to 52 ind. M?2 for T. longicaudata. The mean dry weight biomass of these two species ranged from 14 to 616 and from 19 to 105 mg?2. Length frequency distributions indicate a life span of just over two years for T. inermis and T. longicaudata. Growth took place from about April to autumn with no apparent growth during winter. Maturation and spawning seem to occur after two years for T. inermis and one year for T. longicaudata. Main spawning occurred from May to June coinciding with the spring phytoplankton bloom. Captive spawners of T. inermis (total length 17-22 mm) shed 30-110 eggs per female in a single batch.