TRANSPLANTATION-TAGGING-EXPERIMENTS IN PRELIMINARY STUDIES OF MIGRATION OF COD OFF NORWAY

Cod along the Norwegian coast show great variability in migration habi t. Coastal cod may be stationary for their entire life while mature no rth-east Arctic cod migrate long distances to reach their feeding area s in the Barents Sea and spawning grounds along the Norwegian coast. I n this paper, migratory differences and possible mechanisms behind the m are studied by transplanting the two types of cod to a new location and studying their behaviour after release. Individual behaviour is ex amined by logging information from acoustic transmitters attached to t he fish which give continuous information on position and depth.The da ta, although limited, show clear differences in migratory activity in coastal cod and north-east Arctic cod; the first show a territorial be haviour compared with a more active and determined migration for the s econd. It is apparent that the transplantation of north-east Arctic co d induces migratory activity. Low-frequency noise from oceanic waves i s suggested as a possible navigational clue for north-east Arctic cod to find their way back to oceanic waters. (C) 1995 International Counc il for the Exploration of the Sea