Why and how do cod escape? A field and experimental study of the behaviour of cod prior ro, during and after escape.

Atlantic cod (Gadus morhua L) is a promising new aquaculture species. Experiences from salmon culture strongly indicate that it is difficult to develop "escape proof" sea cages. Thus, it is reasonable to assume that escape also will become a problem in fu ture cod culture. Besides representing a considerable economic loss, escape of cultured cod might also have negative environmental impacts. Norwegian coastal waters host important nursing, feeding and spawning grounds for wild Atlantic cod, and the fisher ies are of immense commercial importance. Considering the ecological and economical importance of cod, precaution seems appropriate. The main objectives of the proposed project are to investigate the causal mechanisms for cod escape, both under experiment al and applied conditions, and to study the spatial and temporal movements of escaped cod. The study will yield knowledge that contribute to technological adaptation and optimisation, as well as improved surveillance and recapture fishery of escaped cod. In addition, the project will provide basic knowledge for evaluation of possible ecosystem effects and consequently also development of mitigating actions. The proposed project corresponds with the aims of the Norwegian Research Council regarding aquacult ure research, because it will establish basic competence and relevant knowledge for development of a viable cod farming industry.