Chapter V — Marine Mammal Strandings and Die-Offs 



A total of 144 animals were diagnosed as having 

 leptospirosis during the seven-month period. In view 

 of the fact that leptospirosis outbreaks occur periodi- 

 cally, this was not judged to be alarming. In several 

 cases, animals were found with bladder cancers, un- 

 usual seizure disorders, and unusual skin diseases. 

 Organizations involved in rescuing and rehabilitating 

 sick and injured sea lions and other marine mammals 

 in California are looking for further unusual occur- 

 rences of this nature. 



Bottlenose Dolphins in Biscayne Bay 



During the 1990 die-off of bottlenose dolphins 

 (Tursiops truncatus) in the Gulf of Mexico, the 

 National Marine Fisheries Service's Southeast Fisher- 

 ies Science Center obtained a permit to take animals 

 from the Gulf of Mexico exhibiting unusual lesions or 

 behavior. In December 1990, researchers working in 

 Biscayne Bay on Florida's east coast observed bottle- 

 nose dolphins that appeared to be infected with a 

 fungal skin disorder known as lobomycosis. By April 

 1991, the incidence of infected animals seemed to be 

 increasing. The Center therefore requested an emer- 

 gency modification of its permit to allow collection of 

 tissue (biopsy) samples from the infected animals. 



On 1 May 1991, the National Marine Fisheries 

 Service requested the Commission's comments on the 

 emergency authorization request. The Commission, 

 in consultation with its Committee of Scientific 

 Advisors, reviewed the request and, by letter of 7 

 May 1991, recommended that it be approved. Subse- 

 quently, the presence of lobomycosis was confirmed 

 in one animal that stranded. Fortunately, there was 

 no subsequent increase in strandings, suggesting that 

 the disease had not caused or contributed to a substan- 

 tial increase in dolphin mortalities. 



Deyelopment of a National Die-OfT 



Response Plan and Improyement of 



tiie Regional Stranding Networks 



As noted in previous Annual Reports, the Commis- 

 sion sponsored a workshop in 1977 to assess the 

 possible causes of mass marine mammal strandings 

 and to determine how the scientific value of both live- 



and dead-stranded marine mammals might be en- 

 hanced. The workshop participants recommended, 

 among other things, that regional networks of volun- 

 teers be established to improve reporting and investi- 

 gation of strandings of both live and dead animals (see 

 Appendix B, Geraci and St. Aubin 1979). In re- 

 sponse, the National Marine Fisheries Service, in 

 consultation with the Commission, has worked with 

 public display facilities, museums, and other interest- 

 ed organizations and individuals to establish volunteer 

 stranding response networks in each of its manage- 

 ment regions. 



In 1987, the Service sponsored a workshop to 

 review operation of the regional stranding networks. 

 In 1989, the Service initiated an in-depth review of its 

 policies and programs regarding marine mammal 

 strandings. The workshop proceedings and the report 

 of the program review were published in 1991, and 

 can be obtained from the National Marine Fisheries 

 Service. 



The stranding networks played an important role in 

 detecting and investigating the unusually high mortali- 

 ty of bottlenose dolphins that occurred along the U.S. 

 mid-Atlantic coast from June 1987 through January 

 1988. The networks also were responsible for detect- 

 ing, and provided assistance in investigating, the 

 unusually high numbers of humpback whales that died 

 in Cape Cod Bay in December 1987, the unusually 

 high numbers of bottlenose dolphins that died in the 

 Gulf of Mexico in 1990, the unusually high mortality 

 of seals in Long Island Sound in spring 1991, and the 

 outbreak of leptospirosis in California sea lions in the 

 summer of 1991. 



As noted in previous Annual Reports, the Minerals 

 Management Service, the Fish and Wildlife Service, 

 the Smithsonian Institution, and many private and 

 volunteer organizations, as well as the Commission 

 and the National Marine Fisheries Service, have 

 contributed to development of the regional stranding 

 networks. 



Response Planning 



As noted in the previous Annual Report, on 18 

 December 1990, the National Marine Fisheries 

 Service, in response to a Commission recommenda- 



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