west Atlantic harp seals (Pagophilus groenlandicus). J. 

 Fish. Res. Board Can. 35:1249-1261. 



Bellairs Research Institute ofMcGill University 

 St James, Barbados, West Indies 



Marine Fish Division 

 Fisheries Research Branch 

 Department of Fisheries and Oceans 

 P.O. Box 1006, Dartmouth 

 Nova Scotia, B2Y4A2 Canada 



Wayne Hunte 



Robin Mahon 



INCIDENTAL CATCH OF 



HARBOR PORPOISE, PHOCOENA 



PHOCOENA (L.), IN HERRING WEIRS IN 



CHARLOTTE COUNTY, NEW BRUNSWICK, 



CANADA 



In this report we examine the indirect exploitation of 

 harbor porpoises, Phocoena phocoena, by the weir 

 fishery for herring (Clupea harengus) in Charlotte 

 County, New Brunswick, in the lower Bay of Fundy. 

 This fishery is of considerable economic importance 

 to the region; the landed value averaged 2.2 million 

 dollars annually from 1974 to 1979 (table 11 in lies 

 1979). Although herring constitute 50% of the harbor 

 porpoise diet (Smith and Gaskin 1974), the level of 

 competition and conflict between P. phocoena and 

 the fishery is unknown. 



The harbor porpoise is taken accidentally by 

 several commercial fisheries throughout the world 

 (Mitchell 1975), including a pound net fishery in 

 Denmark (Andersen 1974) similar to the weir fishery 

 of eastern Canada. In Canadian waters, harbor por- 

 poises have been caught frequently in Newfoundland 

 cod traps (Sergeant and Fisher 1957) and an un- 

 known number are killed annually in gill nets in the 

 Gulf of St. Lawrence (Laurin 1976). In addition to the 

 indirect catch in the Bay of Fundy, harbor porpoises 

 have been hunted for food and oil by native people 

 and fishing families from at least the 19th century to 

 the present (Gilpin 1878; Leighton 1937; Prescott et 

 al. 1981). An unknown number of animals were also 

 used as mink food in the 1950s (Fisher and 

 Harrison 1970). 



As part of a continuing study of P. phocoena, we had 

 the opportunity to examine 48 specimens trapped in 

 herring weirs since 1969. Eleven were tagged or 

 equipped with radio-telemetry packs and released 

 (Gaskin et al. 1975). The remainder were routinely 

 autopsied and ages of 30 specimens were estimated 



from dentinal growth layers (Gaskin and Blair 1977). 

 Since no formal reporting system exists, we at- 

 tempted to assess the annual rate of entrapment by 

 mailing questionnaires to all 214 members of the 

 Fundy Weir Fishermen Association in 1980. A total 

 of 49 questionnaires were returned, of which 36 

 (16.8%) were of a usable nature. 



Specimens Examined from Herring Weirs 



The 48 harbor porpoises examined between 1969 

 and 1982 consisted of 22 females and 26 males. Har- 

 bor porpoises became trapped in weirs from May to 

 December with the majority (36) taken in July and 

 August. Ages ranged from to 8 yr, with a dispropor- 

 tionate number of 1-yr-old animals. Over half (52%) 

 of the aged sample {n = 25) taken from 1969 to 1973 

 consisted of 1-yr-old harbor porpoises, while 

 yearlings constituted only 18.9% of a sample of 95 

 animals collected by shotgun from the free-ranging 

 population during the same time period (Fig. 1). 



This catch bias may be a consequence of the inex- 

 perience of 1-yr-old harbor porpoises in echoloca- 

 tion, navigation, and prey capture. Phocoena 

 phocoena has a lactation period of only 8 mo (Gaskin 

 et al. 1981), short in comparison with other odon- 

 tocete species. Brodie (1969) suggested that pro- 

 longed lactation in odontocetes is attributable to the 



60 - 



50 



Z 



IAJ 



<-> 30 



10 



□ WEIR CAUGHT 

 D SHOT AT SEA 



H n 



-r-R- 



AGE 



FIGURE 1. — Frequency histogram of age classes (estimated from 

 dentinal growth layers) of harbor porpoises collected in the Bay of 

 Fundy, 1969-73, expressed as percentage of totals captured by two 

 methods: Weir-caught (n = 25) and shot at sea (n = 95). 



660 



FISHERY BULLETIN: VOL. 81, NO. 3, 198:1. 



