A Variation in the Mortality of European Anchovy and European Pilchard After Sieving and Discarding from a Purse Seine Fishery in the Eastern Mediterranean

Abstract

Discard mortality of European anchovy (Engraulis encrasicolus) and European pilchard (Sardina pilchardus) was investigated during commercial purse seine fishing operations off İzmir Bay, Turkey. In total, 6703 anchovy and 2545 sardine individuals were observed for seven days in five survival experiments carried out from March to October 2019. Only in March, fish cages were used and observed by divers. In the other trials, fish were observed in holding tanks; dead fish were collected and any surviving fish were fed. In the study, we compared the mortality of sorted and unsorted fish. The GLM model for European anchovy demonstrated a highly significant category effect (p<0.0001) and a highly significant interaction between length-related mortality and season (CL: season; p<0.0001). There were also significant differences in length-related mortality ratio according to the different categories in both seasons (p<0.0001). However, there was a highly significant interaction between mortality ratio, length, uncrowded category, and spring (p<0.005) for European pilchard. The observations showed that high mortalities occurred in the sorted fish categories of both pelagic species during the experiments.