MARINE MAMMAL COMMISSION — Annual Report for 1995 



the Gulf of Maine/Bay of Fundy harbor porpoise 

 stock clearly met the strategic stock criteria and that 

 a take reduction team should be formed immediately. 



By letter of 24 February 1995 the Service advised 

 the Commission that it anticipated completing its final 

 stock assessments by early March 1995 and that it 

 would establish a take reduction team for the Gulf of 

 Maine/Bay of Fundy stock of harbor porpoises by the 

 end of March 1995. The Service, however, was 

 unable to meet to this schedule and, as discussed 

 below, pending formation of the incidental-take 

 reduction team for this harbor porpoise stock and 

 preparation of a take reduction plan, the Northeast 

 Multispecies Fishery Management Plan prepared by 

 the New England Fisheries Management Council 

 continued to serve as the basis for managing incidental 

 take of harbor porpoise in the New England sink 

 gillnet fishery. 



The Service circulated its final stock assessments in 

 August 1995. The final assessment for the Gulf of 

 Maine/Bay of Fundy harbor porpoise stock cited the 

 above-noted population estimate of 47,200 animals as 

 the best estimate of abundance and calculated a 

 minimum abundance estimate of 40,297 animals. The 

 assessment also determined that the best estimate of 

 maximum net productivity for the stock was four 

 percent per year and that its potential biological 

 removal level was 403 porpoises per year. Noting 

 that the above-mentioned estimates of incidental take 

 in New England sink gillnets exceed the potential 

 biological removal level, the Service determined that 

 the stock should be considered a strategic stock. 



On 22 November 1995 the Service invited the 

 Commission to participate on a harbor porpoise 

 incidental-take reduction team scheduled to meet early 

 in 1996. The team will be charged with developing 

 and providing the Service with a recommended take 

 reduction plan within 6 months of its establishment. 

 The plan is to include measures that would immediate- 

 ly reduce harbor seal incidental-take levels to below 

 the potential biological removal level for the entire 

 stock and to reach levels approaching a zero mortality 

 and serious injury rate within five years. As the 

 Service is required to review and take appropriate 

 action to implement the plan within six months of 



receiving the team's plan, measures to meet this goal 

 must be in effect no later than spring 1997. 



Use of Acoustic Alarms To Deter 

 Harbor Porpoises from Nets 



Between 1991 and 1993 the National Marine 

 Fisheries Service supported studies to investigate the 

 use of acoustic deterrents to prevent harbor porpoise 

 entanglement in nets. The work, carried out by 

 commercial fishermen and scientists with the Memori- 

 al University of Newfoundland, Canada, the New 

 England Aquarium, and other institutions, involved 

 attaching acoustic alarms (pingers) to nets to divert 

 approaching animals and thereby prevent their entan- 

 glement. Although used with some success in other 

 fisheries to prevent baleen whales entanglement, 

 experiments with other cetaceans had not proved 

 useful. 



Results of the initial work on harbor porpoise, 

 however, were encouraging and early in 1994 the 

 Service convened a scientific panel to review the 

 harbor porpoise deterrent work and determine whether 

 further experimentation was warranted. Based on the 

 panel's recommendations, the New England Aquarium 

 proposed an experimental protocol to test pingers on 

 the nets of cooperating gillnet fishermen in an area off 

 New Hampshire where the bycatch of harbor porpois- 

 es had been high. As described in the previous 

 annual report, the Commission commented on the 

 experimental protocol early in the fall of 1994. 



Between October and December 1994 the study 

 was carried out with funds provided by the Service 

 and the National Fish and Wildlife Foundation. The 

 study used a double-blind sampling protocol in which 

 an equal number of gillnets were deployed with active 

 and inactive alarms and the incidental catch of harbor 

 porpoise was recorded by independent observers. 

 Neither observers nor fishermen knew whether 

 deployed nets were equipped with active or inactive 

 alarms and the alarms were changed by a third party 

 after each set. 



On 25 July 1995 the New England Fishery Man- 

 agement Council provided the Commission with a 

 draft study report, requesting comments on its find- 



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