Norwegian Spring-Spawning Herring & Northeast Arctic Cod : 100 Years of Research and Management

Gjengitt med tillatelse av Tapir Akademisk Forlag. Hjemmeside: http://www.tapirforlag.no

Loddeundersøkelser med F/F "G. O. Sars" i Barentshavet i februar-mars 1973

During the period 16 February-3 March 1973 R. V. «G. O. Sars» carried out a survey on spawning and prespawning capelin in the Barents Sea. The investigations were a continuation of those reported by Monstad and Midttun 1973. In the area north of the Skolpen Bank the distribution and maturity stage of the capelin were as reported by the mentioned authors. However, during the last week of February an influx towards the Norwegian coast of spawning capelin was observed off the Murman Coast. It is believed that these schools had been moving southwestward east of the area covered by the earlier investigations in the winter season

Length and species dependent diurnal variation in catch rates in the Norwegian Barents Sea bottom trawl surveys

Diurnal variation in capture efficiency may add to the variability in swept area estimates (or indices) from bottom trawl surveys. In the present study the relationship between the day/night ratio of swept area estimates and fish length was examined for 5 species observed in the Barents Sea bottom trawl survey in winter in the years 1989-1996. Generally, most species showed increased catch rates during day light at all sizes as compared with darkness. For cod and haddock a substantial reduction in the day/night ratio with fish length was observed. Some possible behavioural explanations for these findings are discussed for cod. In addition is there a tendency that increased stock size increases the difference in catch rates for both cod and haddock. The implications of the findings for the conduct of the surveys and the reliability of swept area estimates/indices are considered