Microbiological Analysis of Striped Bass (Morone saxatilis) Grown in a Recirculating System†

Abstract

The skin, gills, intestines, tank water, and diet of striped bass grown in recirculating tanks were examined for quantity and quality of microflora. Plate counts for the fish and water samples were similar to counts reported in other systems. The bacteria groups represented most frequently in isolates from the fish were Aeromonas (14%), Moraxellaceae (15%), the Flavobacterium-Chryseobacterium-Cytophaga-Sphingobacterium group (11 %), Bacillus (8%), Group I Pseudomonas (6%), the Shewanella-Alteromonas group (6%), and Comamonadaceae (5%). The food-borne pathogens Staphylococcus aureus, motile Aeromonas spp., and Vibrio mimicus were isolated repeatedly. V. parahaemolyticus and V. cholera were each isolated once, and no Listeria, Plesiomonas, Salmonella, or Yersinia enterocolitica were isolated. Close taxonomic relationships were observed among some of the bacteria found on the fish and in the water; bacteria from the skin and gills were more likely to be related to each other and to the water isolates than to the intestinal isolates. Some bacteria in the intestines originated in the diet, but these strains did not significantly affect the overall microflora of the fish and water.