368 
Fishery Bulletin 107(3) 
122°30'0"W 122°0'0"W 
Figure 5 
Pacific harbor seal ( Phoca vitulina richardii) foraging habitat in San Francisco Bay, 
CA, by season: A) Spring; B) Summer; C) Fall; D) Winter. Areas were designated 
harbor seal habitat if they contained abundances of primary seasonal prey species 
which met or exceeded the thresholds identified in the regression tree analyses. 
Primary seasonal prey species were identified based on strength of correlation in 
the GIS overlay analysis between harbor seal telemetry locations and abundance 
of individual prey species. 
study were likely foraging on these species because 
of their close proximity to the harbor seals’ primary 
haul-out site during the annual molt. Longer-range 
foraging trips by harbor seals tend to occur outside 
of the molting and pupping seasons (Thompson et 
ah, 1989). 
Fall prey species 
Harbor seals in SFB frequently visit areas where ben- 
thic fish species common in SFB are found in greatest 
abundance. Adult plainfin midshipman tend to burrow 
into the sand during the day, emerging at night to 
