The source of vibrio bacteria is marine waters and several species of Vibrio are know to cause epidemics and deaths in hatcheries used to raise fish, oysters, clan-Ls, and eels. Moreover, human diseases transmitted via marine waters have been reported to be caused by the infection of at least 9 different species of Vibrio. These results indicate that manuals as well as invertebrates are susceptible to vibrio infections. In this regard, marine mammals, especially those reared in sea pens, appear to be at high risk to vibrio infections. However, the susceptibility of marine mammals to vibrio infections and diseases has not been documented. The objective of this study was to evaluate the methods to determine the concentrations and kinds of vibrio bacteria in the sea pens used to raise marine mammals as compared to other marine water sites used for other purposes. The membrane filtration technique using several selective media (TCBS, TCBS +7% NaCl, TSAT, MAAC, TTG, mVP, VV) were used to recover and enumerate vibrio bacteria. Enrichment broths were also used to recover selected species of Vibrio. Vibrio bacteria recovered from water samples and from marine mammals were compared based on their species identification and antibiotic susceptibility patterns.