Spatial migration pattern of deep-sea redfish (Sebastes mentella Travin) of the Norwegian-Barents population from survey data
Original version
This report is not to be cited without prior reference to the authorsAbstract
Study of redfish migration by traditional tagging-methods faces great difficulties. The redfish
taken onboard a vessel usually prove to be nonviable. A sharp hydrostatic pressure differential is
lethal for the redfish having a closed swim bladder.
The main purpose of the present paper is to determine migration pattern of the deep-sea redfish
juveniles. To study the deep-sea redfish migration, data from annual Russian and Norwegian
scientific trawl surveys conducted during autumn and winter of 1982-1995 were used.
The Petersen method was applied to analyse size composition of the deep-sea redfish catches
taken during the above trawl surveys. The conclusion made from prior researches that the deepsea
redfish year classes of 1982 and 1988 were strong compared to their neighboring ones was
confirmed.
On the assumption that "peaks" in the length distributions of survey catches displayed strong
yearclasses, the annual corresponding lengths were defined for the 1982 and 1988 year classes of
deep-sea redfish at different age (from 0 to 7 years). Subsequently, using the database from trawl
surveys and knowing the length of the deep-sea redfish from strong yearclasses at different age,
the distribution of these yearclasses by year was mapped. Based on the analysis of these maps,
migration patterns of the deep-sea redfish juveniles in the Barents and Norwegian Seas were
plotted.