QUANTITATIVE AND QUALITATIVE BACTERIOLOGY OF 

 ELASMOBRANCH FISH FROM THE GULF OF MEXICO 1 



John D. Buck 2 



ABSTRACT 



Twelve species of elasmobranch fish (8 sharks, 2 rays, 1 skate, and 1 guitarfishi taken from the Gulf of 

 Mexico off Sarasota. Florida, were studied. Numbers of bacteria on skin were recorded, as were types of 

 bacteria occurring on skin, gills, teeth, and in intestinal contents. Comparative observations were 

 made on eight species of osteichthyan fish and seawater. Counts/cm 2 of elasmobranch skin varied 

 greatly both among genera and within a given species. In general, skin displayed relatively high counts 

 which could be of significance in subsequent flesh spoilage. One brief study of spoilage of nurse shark 

 meat at 5°C and room temperature (24°-26°C) showed that, after 7 days, species of Pseudomonas, 

 Vibrio, and Micrococcus were dominant at the lower temperature while Micrococcus and Proteus 

 vulgaris were recovered at 24°-26°C. Various types of bacteria found in or on the several areas of 

 elasmobranch fish examined were compared with the little information available in the literature. 

 Overall, Gram negative bacteria, particularly the genera Pseudomonas and Vibrio, were most common 

 although several species of Gram positive bacteria were found also. Planococcus isolates from skin may 

 represent important organisms because they have been implicated in shrimp spoilage. Three genera of 

 hemolytic bacteria (Proteus. Staphylococcus, Streptococcus* were recovered from teeth of several 

 elasmobranchs and may present a hazard to bite victims. Also, a variety of enteric bacteria potentially 

 pathogenic to humans was found in intestinal contents; therefore, caution is suggested in handling 

 shark material. 



Considerable information is available on the nor- 

 mal and spoilage microflora of marine fish (e.g., 

 Shewan 1961, 1971; Horsley 1977). However, the 

 bacteriology of the elasmobranchs (sharks, skates, 

 rays) is less understood despite a widespread pre- 

 sent commercial fishery in local areas (Riedel 

 1961; McCormick et al. 1963) and its future poten- 

 tial (Juhl 1973; U.S. Department of Commerce 

 1982). Venkataramen and Sreenivasan (1955) 

 studied the bacterial flora of skin of one shark 

 caught off India; Johnson et al. (1968) charac- 

 terized the intestinal microflora of five species of 

 sharks obtained in the Indian Ocean; and Yap 

 (1979) reported on skin isolates of two sharks 

 freshly caught off Australia. Liston (1957) studied 

 the bacteria associated with slime and gills of 

 fresh North Sea skate. Spoilage bacteria in shark 

 flesh were noted by Wood (1950) in Australia and 

 Velankar and Kamasastri (1955) in India. Al- 

 though the number of shark attacks on humans 

 worldwide is statistically small (Baldridge 1974; 

 Coppleson 1975), there are no substantive data on 

 the potential bacteriological hazard of shark bites 

 other than brief notations of hemolytic bacteria 



'Contribution No. 162 from The University of Connecticut 

 Marine Research Laboratory, Noank, CT 06340. 



2 The University of Connecticut, Marine Sciences Institute, 

 Marine ResearchLaboratory, P.O. Box 278, Noank, CT 06340. 



Manuscript accepted November 1983. 

 FISHERY BULLETIN: VOL. 82. NO. 2, 1984. 



being recovered from the teeth of sharks (Davies 

 1960; Davies and Campbell 1962). 



Consequently, this study was initiated to 

 characterize the numbers and types of bacteria 

 associated with a wide variety of elasmobranch 

 fish common to the Gulf of Mexico. Comparative 

 data were recorded for water and osteichthyan fish 

 caught in the same area. These results will have 

 relevance to the potential spoilage of elasmo- 

 branch meat and the pathobiology of shark bites. 



METHODS 



Sampling Sites 



All fish were obtained from the Gulf of Mexico 

 within several kilometers off Sarasota, Fla., or in 

 the contiguous waters of Sarasota Bay. Small 

 elasmobranchs were caught by use of a long, 

 monofilament gill net set from the surface to a 

 depth of about 1 m. Larger sharks were caught 

 using baited longlines farther offshore. The one 

 sand tiger shark, Odontaspis taurus, studied was 

 obtained from the Mystic Marinelife Aquarium 

 (Mystic, Conn.) and had been dead and refriger- 

 ated for 4 h. This shark, caught off the coast of 

 New Jersey 3 d previously, was maintained in 

 chlorinated brine water at the aquarium for 2 d 



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