AMBIENT-TEMPERATURE AND DISTRIBUTION OF NORTHEAST ARCTIC COD

Many studies on the effects of temperature on fish distribution and po pulation parameters have considered the temperature and its variabilit y at fixed stations or sections rather than the ambient temperature ac tually surrounding the fish. In the present paper ambient winter tempe rature was estimated for 1-7 year-old north-east Arctic cod in the per iod 1988-1995 from spatial distributions of fish density and temperatu re. Four different estimates were calculated for each age and year bas ed on fish density observations from acoustic and bottom-trawl surveys and temperature recordings at the bottom, as well as averaged from 10 0 m depth to bottom. The estimates of ambient temperature were compare d with each other and with temperature series in fixed areas and a sta ndard section, the Kola meridian. The inter-annual variability in ambi ent winter temperature was found to be larger than in the Kola section series. Older fish were found at higher temperatures. For the younger age groups the range extended eastwards when numbers were high. This could explain the observed decrease of mean ambient temperatures in wh ich cod were found during a relatively warm period in the Barents Sea. The mean ambient temperatures are also compared with the temperatures used for calculations of consumption rate by cod in the ICES Working groups.