Cultivable bacterial communities from purse-seined small pelagic fish, fishing nets and storage tanks

Sardines and anchovies are the most important small pelagic species throughout the Mediterranean, caught mainly by purse-seiners. Their rapid bacterial degradation after capture and storage limits their commercial use and shelf life. Gills are the most vulnerable tissue in fish, harboring bacterial communities which have not been previously investigated in these species. This study examined cultivable bacteria from gills of harvested sardines and anchovies, tanks in which they are stored aboard, and fishing nets on four occasions (twice for both warm and cold seasons). A total of 471 bacteria were isolated, belonging to 74 genera and 163 species by MALDI-TOF MS identification. A number of genera and species identified from fish and surfaces occurred only in the warm or cold season, but a fraction occurred in both seasons. Sardine gills harbored most of the isolated bacteria (254), belonging to 53 genera and 111 species, as pposed to anchovy with 120 strains, belonging to 30 genera and 64 species. A diverse cultivable bacterial community consisting of 17 species was isolated exclusively from the polyethylene surfaces of nets and tanks. This finding is significant regarding their potential migrations between planktonic and sessile lifestyles. Possible contamination and cross-contamination are likely to increase with the rise in ambient and seawater temperature during the hauling and sorting of fish in the tanks. The food safety risks stem from pathogens and fish spoilage bacteria on both the fish and the surfaces of fishing nets and storage tanks.