MARINE MAMMAL COMMISSION — Annual Report for 1991 



to be violated with respect to harbor porpoises be- 

 cause the best available data indicate that there is a 

 relatively discrete population of harbor porpoises in 

 central California that may have been depleted as a 

 result of incidental take in set net fisheries. The 

 Commission therefore recommended that the Service 

 consider the possibility that lower localized harbor 

 porpoise densities are the result of incidental taking 

 (for further discussion of marine mammal-fisheries 

 interactions, see Chapter III of this Report). 



Since 1987, the Northeast Fisheries Science Center 

 has been working to develop programs to determine 

 harbor porpoise abundance and incidental take in 

 commercial fisheries in the Gulf of Maine and Bay of 

 Fundy. A program report, published by the Center in 

 December 1991, indicated significantly greater num- 

 bers of harbor porpoises and greater relative levels of 

 incidental take than previously estimated. 



Two at-sea abundance surveys were conducted in 

 the Gulf of Maine and Bay of Fundy in 1991: a 

 primary survey between 22 July-30 August 1991 and 

 a supplementary survey of inshore bays on the coast 

 of Maine from 3-17 August 1991. The survey used 

 a two-team approach to allow correction for animals 

 not seen on the track line. There were uncertainties 

 in determining the exact number of schools seen by 

 both teams simultaneously and, hence, in determining 

 an exact correction factor. Based on a lower and a 

 higher estimate of duplicate sightings, two separate 

 population estimates were derived: 66,000 and 

 45,000 animals, respectively. 



From June 1989 through May 1991, under contract 

 to die Northeast Fisheries Science Center, the Mano- 

 met Bird Observatory in Manomet, Massachusetts, 

 placed observers on commercial groundfish gillnet 

 fishing vessels in the Gulf of Maine to record inciden- 

 tal take of marine mammals, seabirds, sea turtles, and 

 non-target fish species. With observers on just over 

 one percent of commercial fishing trips during the 

 period, 34 harbor porpoises were observed taken 

 incidental to fishing activities. Extrapolation of tiiese 

 data result in preliminary estimates of approximately 

 1,250 animals per year being caught and killed. This 

 number equals about 2.8 percent per year of the 

 Northeast Fisheries Science Center's lower population 



abundance estimate and about 1 .9 percent per year of 

 the higher estimate. 



On 13 December 1991, the National Marine 

 Fisheries Service published a notice in the Federal 

 Register announcing that on 18 September 1991 it had 

 received a petition from the Sierra Club Legal De- 

 fense Fund on behalf of the International Wildlife 

 Coalition and 12 co-petitioners to list the Gulf of 

 Maine/Bay of Fundy harbor porpoise population as 

 threatened under the Endangered Species Act. 



At the end of 1991, the Marine Mammal Com- 

 mission had not been informed of any further actions 

 regarding the Service's status review of harbor 

 porpoises in the northwest Atlantic. The Commission 

 was also anticipating action by the Service on the 

 petition for protective listing. 



Bottlenose Dolphin 

 {Tursiops truncatus) 



The bottlenose dolphin is found throughout temper- 

 ate and tropical waters of the world, commonly in 

 nearshore waters. It is the most common cetacean 

 species in the coastal waters of the southeastern 

 United States, and the cetacean species most frequent- 

 ly maintained in captivity for public display and 

 scientific research. Capture of bottlenose dolphins for 

 these purposes began in the 1900s in the United 

 States. Considerable, though unknown, numbers of 

 animals were taken prior to the enactment of the 

 Marine Mammal Protection Act in 1972. Since that 

 time, when a permit procedure for taking of marine 

 mammals was implemented under the Act, more than 

 500 bottlenose dolphins have been collected. 



Although the status of local or regional populations 

 is often unclear, it is unlikely that captures and 

 removals alone have caused significant declines in the 

 affected dolphin populations. Unusually high numbers 

 of bottlenose dolphins died and washed up on beaches 

 from New Jersey to Florida along the U.S. Atlantic 

 coast in 1987-1988. This happened again in 1990 

 along die coast of the Gulf of Mexico. (See Chapter 

 V for further discussion of marine mammal strandings 

 and mortality). In addition, unknown but perhaps 



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