Effects of artificial light on trawl catch and behaviour of Greenland halibut in front of trawls

摘要

Development of methods for visual surveying in deepwater often rely on the use of constant artificial light. Conclusions relating to vulnerability and other aspects of fish behaviour in front of trawls during normal fishing operations may be biased due to the fish reacting in response to the light. The purpose of this study was to evaluate the effect of light on catch level and catch composition of Greenland halibut (Rheinhardtius hippoglossoides) in trawl surveys, and also to determine how the light influences behaviour of individual fish in front of the trawl. We used flash-photos to record behaviour in dark conditions and compared the results with hauls using video and constant artificial light.