Pitt, T. K. 



1964. Fecundity of the American plaice, Hippoglossoides 

 platessoides (Fabr.) from Grand Bank and Newfoundland 

 areas. J. Fish. Res. Board Can. 21:597-612. 

 Simpson, A. C. 



1951. The fecundity of the plaice Fish. Invest. Ministr. Agric 

 Fish. Food (GB), Ser. II, 17(5):l-27. 

 Stepanenko, M. A. 



1980. Reproductive conditions and the assessment of the 

 spawning part of the Pacific hake, California anchovy, horse- 

 mackerel, and some other fish species in the California Cur- 

 rent Zone in 1979. Pac. Inst. Fish. Oceangr. (TINRO), 

 Manuscr. Rep., 29 p. 



Thomson, R. E. 



1981. Oceanography of the British Columbia coast. Can. 

 Spec Publ. Fish. Aquat. Sci. 56, 219 p. 



Utter, F M., and H. 0. Hodgins. 



1971. Biochemical polymorphisms in the Pacific hake (Merluc- 

 cius productus). Rapp. P.-v. Reun. Cons. int. Explor. Mer 

 161:87-89. 



WlBORG, K. F 



1951. The whirling vessel: An apparatus for the fractioning 

 of plankton samples. Rep. Norw. Fish. Mar. Invest. 9(13): 

 1-16. 



J. C. Mason 



Department of Fisheries and Oceans 



Fisheries Research Branch 



Pacific Biological Station 



Nanaimo, British Columbia V9R 5K6, Canada 



STRANDED ANIMALS AS INDICATORS OF 



PREY UTILIZATION BY HARBOR SEALS, 



PHOCA VITULINA CONCOLOR, IN 



SOUTHERN NEW ENGLAND 



Since Federal protection began in 1972, the New 

 England population of harbor seals, Phoca vitulina 

 concolor, has more than doubled (Gilbert and Stein 

 1981 1 ; Payne and Schneider 1984), increasing at a 

 site in southeastern Massachusetts at an average 

 rate of 11.9% per year (Payne and Schneider 1984). 

 One of the primary management concerns regarding 

 the New England seal population is the increasing 

 potential for conflict between commercial fisheries 

 and harbor seals (Prescott et al. 1980 2 ). 

 Seals have been shown to be significant consumers 



Gilbert, J. R., and J. L. Stein. 1981. Harbor seal populations 

 and marine mammal fisheries interactions. National Marine Fish- 

 eries Service, NOAA, Northeast Fisheries Center, Contract No. 

 NA-80-FA-C-00029, Woods Hole, MA 02345, 55 p. 



2 Prescott, J. H., S. D. Kraus, and J. R. Gilbert. 1980. East 

 Coast/Gulf Coast Cetacean and Pinniped Workshop. Marine Mam- 

 mal Commission (MMC), Final Report, Contract 79/02. (Available 

 National Technical Information Service, Springfield, VA 22151 as 

 PB80-160104, 142 p.) 



of marine production (Brodie and Pasche 1982) and 

 have been implicated as competitors for commer- 

 cially valuable fish stocks, impacting fisheries 

 through direct predation, gear damage, and en- 

 tanglement (Boulva and McLaren 1979; Everitt and 

 Beach 1982; Brown and Mate 1983). Despite the 

 significant increase in harbor seal abundance, only 

 anecdotal information exists on the diet of harbor 

 seals along the eastern United States, lb assess the 

 impact of this common predator on fish and squid, 

 information is required on the food species exploited. 



In the past, seals were killed to facilitate quanti- 

 tative analysis of their stomach contents (Imler and 

 Sarber 1947; Spalding 1964; Boulva and McLaren 

 1979; Pitcher 1980a), although this procedure is im- 

 practical in New England. Two alternatives to this 

 method are the analysis of the stomachs of strand- 

 ed animals, and the examination of seal feces col- 

 lected on accessible haul-out sites (Pitcher 1980b; 

 Treacy and Crawford 1981; Brown and Mate 1983). 



The first alternative for determining the food 

 habits of the southern New England seal population 

 was provided by the more than 500 harbor seals that 

 have been found stranded south of Maine since 1977. 

 The stranded seals were collected by the New 

 England Aquarium (NEA), Boston, MA. The major- 

 ity (59%) of the seals were collected between January 

 and March (Table 1) along the perimeter of Cape Cod 

 Bay, MA, primarily on the eastern side. This corre- 

 sponds to the time when the peak number of seals 

 occur south of Maine (Schneider and Payne 1983). 

 Most of the stranded seals (65%) came from one 

 year, 1980 (Table 1), when over 445 seals died of 

 acute pneumonia associated with influenza virus 

 (Geraci et al. 1982). 



Upon necropsy at the NEA, most of the stomachs 

 and intestinal tracts of the stranded seals were found 

 to be empty. Only 63 stomachs contained food mat- 

 ter, and the contents from those were frozen for later 



Table 1.— Monthly distribution of stranded P. v. concolor contain- 

 ing prey items examined 1977-83. 



FISHERY BULLETIN: VOL. 84, NO. 1, 1986. 



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