Chapter II — Species of Special Concern 



the first four months of 1999 to the plaintiffs by 31 

 July 1999. Thereafter, the Service will provide the 

 plaintiffs and the public with quarterly updates of 

 harbor porpoise take levels. The Service also pledged 

 to provide the plaintiffs by 30 June 1999 information 

 on the status and scope of a research program to 

 investigate the effects of pingers on the marine eco- 

 system and the potential for harbor porpoise habitua- 

 tion to or displacement by pingers. 



Bottlenose Dolphin 

 (Tursiops truncatus) 



Bottlenose dolphins occur throughout the world 

 both inshore and offshore in temperate and tropical 

 waters. It is the most common cetacean in the coastal 

 waters of the southeastern United States and is the 

 marine mammal species most likely to be affected by 

 fisheries, oil and gas exploration and development, 

 and other human activities in those waters. The 

 bottlenose dolphin also is the cetacean species main- 

 tained most frequently in captivity for public display 

 and scientific research. 



Between June 1987 and March 1988 more than 

 700 bottlenose dolphins were found dead along the 

 Atlantic coast between New Jersey and Florida (see 

 Chapter V for information on this and subsequent 

 marine mammal unusual mortality events). The 

 National Marine Fisheries Service estimated that this 

 mass mortality may have reduced the mid-Atlantic 

 coastal migratory population of bottlenose dolphins by 

 as much as 60 percent. On 11 November 1988 the 

 Center for Marine Conservation petitioned the Service 

 to list that population as depleted under the Marine 

 Mammal Protection Act. Subsequently, the Service 

 proposed and on 6 April 1993 listed the population as 

 depleted. 



As noted in its 1993 annual report, the Commis- 

 sion recommended on three separate occasions that the 

 Service not list the population as depleted without 

 simultaneously describing the steps that would be 

 taken to decide when it had recovered. Toward this 

 end, the Commission recommended that the Service 

 develop and implement a conservation plan for the 

 affected population. On 6 April 1993, the date that it 



published notification of the depletion listing, the 

 Service advised the Commission that it planned to 

 prepare a conservation plan that would address the 

 means for determining when the population had 

 recovered. 



There also have been several unusual mortality 

 events involving bottlenose dolphins in the Gulf of 

 Mexico. As noted in previous Commission reports, 

 morbillivirus was determined or suspected to be the 

 cause of several of these events. Because of uncer- 

 tainty concerning the effects of the events on popula- 

 tion size and productivity, the National Marine 

 Fisheries Service requested in August 1990 that 

 organizations holding permits to collect bottlenose 

 dolphins for public display refrain from doing so 

 unless absolutely necessary to maintain a display. 

 Permit holders agreed and, since that time, no 

 bottlenose dolphins have been taken from U.S. waters 

 for public display. Instead, facilities are maintaining 

 displays by breeding previously captured animals. 



Although live captures and removals are no 

 longer a concern, there is growing evidence that 

 incidental take in fisheries may be adversely affecting 

 some bottlenose dolphin populations. In some areas, 

 the estimated incidental take in fisheries is greater 

 than the calculated potential biological removal level 

 for the affected populations. As noted in Chapter IX, 

 boaters feeding and otherwise interacting with wild 

 dolphins also are a growing concern. As noted in 

 Chapters VI and VII, it also is not clear whether 

 offshore oil and gas exploration and development or 

 other activities in the northern Gulf of Mexico may be 

 affecting bottlenose dolphins. 



Although there is no evidence that any bottlenose 

 dolphin population in U.S. waters currently is declin- 

 ing, there are several reasons for concern: 



• it is uncertain whether the concentrations of 

 bottlenose dolphins in different geographic areas 

 constitute discrete population units and, if so, the 

 boundaries, sizes, and productivity of those units; 



• the species is long-lived (males can live more 

 than 40 years and females more than 50) and 

 occupies coastal waters affected by a variety of 

 human activities, including pollution; 



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