The migration of coastal cod (Gadus morhua L.) tagged in a fjord of western Norway

Abstract

This study is part of a research program investigating the possibility of enhancing the production of coastal cod via a large scale release of pond produced fish in Masfjorden, a fjord of western Norway. An analysis of parts of the ecosystem are being carried out prior to the large scale experiment with a special focus on the cod population of the fjord. The paper deals with the migration pattern of wild cod which were caught, tagged and recaptured and also, pond produced cod released in small scale tag-release-recapture experiments. We applied Spearman's rank correlation test and Kolmogrov-Smirnov two-sample test to assess whether larger individuals migrate longer distances than smaller cod. The major proportion of the immature wild and pond produced cod were nearly stationary and only 15.0 and 7.0 percent, respectively were recaptured more than five kilometers from the release site. However, a larger proportion, 54 percent, of mature cod were recaptured outside the release site, of which the !argest individuals were found to migrate the longest distances, with some of the latter intermingling with cod from contiguous fjords.