Prosjekt 900945 Studier av fiskeatferd og redskapsparametre for videreutvikling av teineteknologi
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This project is based on earlier research activities and focused on the development of an efficient cod pot. Fishing trials and behavioural studies were carried out with two-chamber pots that were set on the bottom and floated off the bottom at two different distances (35 cm and 95 cm). Behavioural studies were also conducted with two different designs of the “Lofoten pot” (with a closed and an open lower chamber, respectiviely). Survival of cod caught in pots was studied by holding fish in tanks. Two-chamber pots that were floated 35 cm off the bottom gave highest catch rates for cod, 28 % and 43 % higher than bottom set pots and pots floated 95 cm off the bottom, respectively. Behavioural observations showed that cod searched close to the sea bed when approaching the pots. Cod were often observed swimming into and out of the lower chamber of the Lofoten pot with a closed chamber, and several fish swam into the upper chamber and were caught. For the Lofoten pot with an open lower chamber, fish were seldom seen approaching the entrance leading into the upper chamber, and few were caught. The survival rate of cod held in tanks was 74 %. Dead fish were floating, had gas bobbles in the blood, stiff body, distended gill covers and open mouth. Physiological parameters (pH, lactate, glucose) showed that the fish were less affected by the catching process compared with fish caught by Danish seine. The present results and earlier experiments indicate that pot is an efficient fishing gear for catching cod under certain conditions, and pot may prove to be a viable gear for capture-based aquaculture.