428 



Fishery Bulletin 100(3) 



these families; rather than ignore their occurrence, these 

 species were pooled and mass estimates were based on 

 measurements of wattled eelpout and sandfish otoliths 

 (Table 5). The family Scorpaenidae was composed mostly 

 of juvenile fish (Sebastes and Sebastelobus spp. ) which 

 can seldom be distinguished to species from bones and 

 otoliths. Mass estimates were based on black rockfish (Se- 

 bastes melanops; Table 5). Morphometeric relationships 

 for peamouth (Mylocheilus caurinus) were unavailable in 

 the literature. Peamouth are small, slender members of 

 the minnow family, less than 36 cm in length, with a shape 

 similar to several other small harbor seal prey. Mass was 

 assumed to be less than 100 g. Hexagrammids included 

 lingcod (Ophiodon elongatus) and greenlings (Hexagram- 

 mos spp.) also were poorly represented by otoliths. Mass 

 was estimated from lingcod otoliths (Table 5). Because 

 bones and otoliths were often difficult to identify to spe- 

 cies, flatfish other than starry flounder were pooled and 

 mass was calculated from the average of estimated masses 

 of identified otoliths (rex sole, Glyptocephalus zachirus; 

 English sole, Pleuronectes vetulus; Dover sole, Microsto- 

 mus pacificus; rock sole, Pleuronectes bilineatus; slender 



sole, Eopsetta exilis) for each season. In contrast, starry 

 flounder remains were easily identified and much more 

 abundant than any other flatfish species (Table 4). 



Several taxa were not represented by otoliths because 

 they were completely digested or because the species 

 lacked otoliths. No intact Pacific mackerel {Scomber ja- 

 ponicus) otoliths were recovered from scat and their mass 

 was assumed to be less than 700 g, the upper limit re- 

 ported by Eschmeyer and Herald (1983). Lamprey species 

 included river (Lampetra ayresii) and Pacific lamprey (L. 

 tridentata). Mass was estimated from the upper limit of 

 outgoing Pacific and river lamprey from Pacific Northwest 

 river systems (Beamish, 1980). Little information was 

 available for predicting the mass of elasmobranchs; how- 

 ever, all elasmobranchs (spiny dogfish, Squalus acanthias; 

 and skates, Rajidae) consumed by harbor seals appeared 

 to be juveniles. Elasmobranch mass was extrapolated 

 from a regression of vertebral centrum width on mass 

 from another skate species (Zeiner and Wolf, 1993), yield- 

 ing an upper estimate of 490 g. We assumed the mass of 

 skates and spiny dogfish consumed by harbor seals to be of 

 a similar size, and all less than 500 g. Cephalopod (Loligo 



