Behaviour of saithe penned in different densities.

Abstract

In Norway purse seine catches of live saithe are towed to the coast and kept in net pens until the fish can be processed by the fishing industry. During penning - especially during "short-time" penning - the quality of the fish is often deteriorated by tattered fins and occurence of wounds. The following study tried to find out if anything in the saithe's behaviour in the pens could explain the development of these wounds and if stocking density (6-90 kg fish/m 3 ) inflicted any kind of stress on the fish. Underwater television and heart beat transmitters were used to observe the behaviour. No density dependent difference in heart beat activity could be detected and the fish also seemed to endure very high stocking densities quite well. The saithe also seem to adapt the penning and handling as the pulse returns quicker to normal beat after frightening the fish the longer the saithe have been penned.