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Aquacultured striped bass from indoor flow-through tanks were examined for quantity and quality of microflora. Plate counts were performed at three temperatures (7°C, 22°C, and 35°C) under aerobic and anaerobic conditions. Bacterial loads on the skin, gills, and intestines were similar to those reported for wild striped bass and pond-raised hybrid striped bass. The predominant groups of bacteria isolated were Aeromonas spp. (18%), Flavobacterium/Cytophaga species (15%), Comamonadaceae (15%), Plesiomonas shigelloides (13%), Moraxellaceae (6%), Bacillus spp. (4%), and an unidentified gram-negative rod (9%). Foodborne pathogens Staphylococcus aureus and Vibrio spp. were also isolated.

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.

Aquacultured hybrid striped bass were examined for quantity and quality of microflora. Plate counts were performed at three temperatures (7, 22, and 35°C) under aerobic and anaerobic conditions. Bacterial loads on the skin, gills, and intestines were similar to those reported for wild fish. Plate counts performed at 22°C yielded the highest counts and the greatest variety of species. The predominant groups of bacteria isolated were Aeromonas spp. (27%), coryneforms (14%), Pseudomonas spp. (12%), Flavobacterium/Cytophaga/Sphingobacterium group (8%), Plesiomonas shigelloides (7%), Bacillus spp. (7%), and Enterobacteriaceae (6%). Human foodborne pathogens Listeria monocytogenes , Staphylococcus aureus , Shigella dysenteriae , Vibrio spp., and Yersinia pseudotuberculosis were also isolated. There were no indications, however, that pond-raised fish present a higher risk of foodborne illness than do wild fish.

The objective of this study was to determine if a gentle rinse procedure was equivalent to the combination of excision and homogenization with a stomacher for the relative removal of various microorganisms from finfish fillets. Fillets of hybrid striped bass and rainbow trout were obtained from local markets and sampled using three methods: rinse (R), excision followed by homogenization in a stomacher (S), and homogenization of fillets following a rinse (RS). Microorganisms were enumerated on selective and nonselective media, and randomly selected colonies from aerobic plate counts were identified using MIDI Sherlock and BIOLOG microbial identification systems. Enrichments and selective media were used for the isolation of Listeria monocytogenes, Salmonella spp., and Yersinia enterocolitica. This study confirms previous reports that stomaching is superior to rinsing for enumerating total microbial populations from fish fillets. Rinsing was more effective for rainbow trout than for striped bass. Sampling method did not affect the relative magnitude of plate counts on media selective for aeromonads, pseudomonads, Shewanella, lactic acid bacteria, enterics, and gram-positive cocci. In the compositional analysis of random isolates, R recovered significantly lower fractions of aeromonads than did S or RS, but sampling method did not affect the percent recovery of lactic acid bacteria, pseudomonads, Shewanella, Moraxellaceae, or Cytophaga/Flavobacterium. However, observations suggest that with increased replication, differences among Moraxellaceae, Pseudomonas, and gram positives might be significant. Only one L. monocytogenes colony was isolated, and no Salmonella or Y. enterocolitica, so the effect of sampling method could not be determined for these organisms. Differences in predominant bacterial populations were seen between fish species.