examination. In the fall of 1983, we pilot-tested the 

 analysis of stomach contents from stranded seals 

 using those 63 stomach samples as an indicator of 

 prey utilization. The objectives of this study were 1) 

 to identify prey items selected by seals in southern 

 New England and 2) to determine whether stomach 

 contents from stranded animals can provide accurate 

 information on the utilization of most kinds of prey. 



Methods 



The stomachs were thawed and the contents wash- 

 ed with water through a series of nested sieves (1.80, 

 1.00, and 0.50 mm 2 ). Identifiable materials were 

 rough-sorted into fish and fish components, inverte- 

 brates and invertebrate components. Intact speci- 

 mens and cephalopod beaks were preserved in a 70% 

 ethanol-30% glycerin solution. Persistent prey hard 

 parts (primarily otoliths) were removed and stored 

 dry in glass vials. 



Otoliths from the stomach samples were identified 

 against a reference collection at the National Marine 

 Fisheries Service, Northeast Fisheries Center 

 (NMFS/NEFC), Woods Hole, MA. Cephalopod beaks 

 were identified against a reference key (Clarke 1962). 



To estimate the size of fish taken by harbor seals, 

 otoliths removed from the stomach samples were 

 measured under a dissecting microscope using ver- 

 nier calipers. Regression equations relating otolith 

 length to fish length (Frost and Lowry 1980; Brown 

 and Mate 1983) were calculated using measurements 

 obtained from the reference collection of fishes col- 

 lected in the Gulf of Maine, located at the NMFS/ 

 NEFC. Fork lengths were estimated for four prey 

 species. 



Results 



Fifty-three stomachs (84%) held identifiable food 

 items (Table 2). Cephalopod beaks were recovered 

 from 35 stomachs, representing at least 168 in- 

 dividuals and 2 species. Thirty-three stomachs con- 

 tained beaks from the short-finned squid, Illex il- 

 lecebrossus, with a range of 1-22 beaks per stomach. 

 Beaks of the long-finned squid, Loligo pealei, were 

 found in two stomachs, ranging from 4 to 5 beaks 

 per stomach, and accounted for only 5% of the squid 

 recovered. The two species were not found together 

 in any of the stomachs. Twenty-nine stomachs con- 

 tained squid remains and no other type of prey. Six 

 stomachs contained both squid and fish remains. 



Seventeen stomachs contained some fish remains, 

 including intact specimens, copious semidigested 

 flesh, and 121 free otoliths. In total, seven species 



and five families were represented. Fourteen 

 stomachs held otoliths from only one species of fish, 

 while seven stomachs contained otoliths from more 

 than one fish species. 



Four species of Gadidae comprised the majority 

 of all fish species found in the stomachs of the 

 stranded seals. A total of 86 otoliths in six stomachs 

 were recovered. Haddock, Melanogrammus aegle- 

 finus, was the most frequently found gadid (45 

 otoliths in four stomachs) with a maximum of 24 

 otoliths recovered from a single stomach. Silver hake, 

 Merluccius bilinearis, remains were found only 

 slightly less frequently (34 otoliths from three 

 stomachs). Pollock, Pollachius virens, otoliths were 

 found in one stomach (five otoliths), and two red 

 hake, Urophycis chuss, otoliths of equal length were 

 recovered from one stomach, presumably from a 

 single fish. 



Fifteen free otoliths and three intact specimens 

 of American sand lance, Ammodytes americanus, 

 were recovered from two stomachs, and three 

 stomachs contained otoliths from members of the 

 flatfish family Pleuronectidae 



Two stomachs contained shells: the Atlantic 

 mussel, Mytilus edulis, and the common slipper shell, 

 Crepidula fornicata. 



The estimated mean fork length for the four gadid 

 prey species ranged from 170 to 340 mm (Table 3). 

 Regressions were not available to estimate the 

 lengths of the sand lance found in the stomachs; 

 however, studies on sand lance in Cape Cod Bay 

 found a mean size of 93 mm SL (Richards 1982). 



Table 2. — Analysis of stomach contents from stranded harbor 

 seals, P. v. concolor in Southern New England, 1977-83. 



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