Investigation of catch efficiency and catch composition of bottom trawl fishing depending on several depths and meteorogical criteria in Sinop region

This study was carried out by two commercial bottom trawling vessels hunting at Inceburun locality of Sinop during catch season of 2009-2010 in order to determine the factors which influence the trawl fishing, and to reveal how catch efficiency, catch amount of target species and discard changed under the effect of these factors.A total of 195 catch operation was performed as a result of 40 days at sea during catch season yielding a total catch of 22063,8 kg of which 99,18% was composed of teleostei, 0,55% chondrostei, 0,14 % molluscs, 0,11% mammals and 0,03% crustaceans. 71,1% of the total catch provided economic income and 28,9% were delivered back to sea.As a result, catch amount was found to be different among months reaching at a maximum total catch of CPUE value (70,59 kg/s) in September and dropping to a minimum value during April. Discard amounts were detected to have a fluctuation during the year achieving a maximum value (31,04 kg/s) in January. However, when the rate of economic catch CPUE and discard CPUE was examined, discard rates were found to increase towards the end of the catch season.The depths of the trawl operations conducted throughout the survey were classified as 0-40, 40-50 and >50 fathoms and the highest catch amount (14201,3 kg) was observed at catch areas deeper than 50 fathoms whereas the lowest (2428,5 kg) were recorded at areas of 0-40 fathoms. The most efficient depth in terms of CPUE (122,69 kg/s) was also below 50 fathoms and the least efficient catch areas (58,54 kg/s) were found to be at the depths between 40-50 fathoms. Economic catch and discard reached their highest CPUE (122,69 and 35,62 kg/s) at catch areas deeper than 50 fathoms, economic catch yielded the lowest catch at 0-40 fathoms (41,96 kg/s) and the discard presented with their lowest value between 40-50 fathoms (14,89 kg/s).The influence of various weather conditions on catch amounts were compared and bad weather conditions were found to be more efficient in terms of both total catch amount and CPUE values. Same results were obtained for economic catch and discard rates.The other parameter investigated for its effect on fishing was the wind directions providing a result that the northwestern winds yielded the highest catch amounts (5013,2 kg), northeastern winds were the most efficient (58,65 kg) in terms of CPUE values, and the southwestern winds being the least productive both for total catch amount and CPUE values (218 kg, 28,13 kg/s). The wind directions which yielded catch of economic species gave similar results to those of total catch amounts. On the other hand, the discard produced the highest total catch amount and CPUE value during easterly wind, the lowest total catch during southwestern winds and lowest CPUE values during northern winds.