Videotape documentation of salmon (Salmo salar) and whitefish (Coregonus lavaretus) reacting to a modified whitefish trapnet

The behaviour of trapped fish inside a whitefish trapnet was documented with an underwater video camera to test whether the trap could be modified to selectively exclude Atlantic salmon (Salmo salar L.). The trapnet was modified and equipped with a cone of orange-coloured twine threads (1.7 mm diameter) tied from the end of the last funnel of the trap to the end of the last fish bag. The reaction of the fish to the modified threaded funnel section was videotaped. The camera was positioned beside the trap funnel so that behaviour could be observed as the fish either entered or avoided the fish bag. Videotape recordings were made for 24 h. The diurnal activity of the fish was also recorded, with the most active period being between 06.00 and 11.00. Species identification from the videotape record was difficult because of the very short time of an observation and because of the quality o f the images. Of 104 observations made during the 24 h, 55 were estimated to be whitefish (Coregonus lavaretuss. str. L.), 28 salmon, and the species of the remaining 21 could not be identified.

Article from Marine Science Symposia Vol. 196 - Fish behaviour in relation to fishing operations. Symposium held in Bergen, 11-13 June 1992. To access the remaining articles please click on the keyword "MSS Vol. 196".