A preliminary study on whiting (Merlangius merlangus) behaviour to bottom-set pot in the Black Sea

Abstract

Due to overfishing and decreasing in fish stocks, interactions between dolphins and deep gill nets have increased rapidly in recent years for the Black Sea. Dolphin-inflicted damage to fishing gear and catch losses have increased along the Black Sea coast of the Turkey and many small-scale coastal fishermen have been severely affected. the bottom set Norwegian two-chamber pot was tested as alternative to deep gill net for preventing dolphin damage and catch losses for whiting (Merlangius merlangus) fisheries in the Black Sea and catch efficiency was found to be very low. in this study, underwater video analyses were made to describe the behaviour of whiting in and around bottom-set Norwegian two chamber pot to determine factors that are related to the catch efficiency. A total of successful 8 deployments were carried out between July 2016 and March 2017 within the boundaries of Rize province (south-eastern Black Sea). Pot was deployed at depths of 55-75 m and a total of 51 hours' video records were obtained by GoPro Hero 4 and Sony action cameras. Results showed that the 98% of observed whiting individuals approached the pot from upstream direction. in addition, it was observed that all of entering the pot occurred from upstream direction. Finally, pots should have a number of entrances to ensure that one of the entrances stays in line with the downstream and the entrances should not be placed in such a way they face each other for improving capture efficiency of whiting.