In Partial Fulfillment of the Requirements for the Degree of
Master of Science in Marine Science
By
Michael L. Torok
July 6, 1994
ABSTRACT
| Thirty-nine harbor seals (12 males, 27 females) were captured from February 1990 to February 1992 in South San Francisco Bay, California. Head-mounted radio transmitters were attached to study movements, daily activity patterns, and dive behavior. Radio-tagged seals used a mean of 2 haul-out sites (SE=0.2, range 1-7). Nine seals moved to the outer California coast at least once, ranging north to Pt. Reyes Headlands and south to Pillar Point. Harbor seal movements were within the entire length of the bay from Alviso Slough to Corte Madera Marsh. Seals spent a significantly greater proportion of time diving at night compared to day (Q=4.3, P<0.001). The proportion of time diving and hauled-out was unrelated to tidal height, harbor seal age or sex, or time of year. Mean dive times were 0.5 (SD=0.3) to 3.3 (SD=1.3) min, and the maximum recorded dive duration was 12.7 min. Fourteen species of fishes, and 1 species of cephalopod were identified from 215 fecal samples collected in San Francisco Bay. Of these species, 5 constituted greater than 86% of the estimated dietary mass. An introduced species of fish, the yellowfin goby (Acanthogobius flavimanus), constituted greater than 54% of the total number of prey items found. |
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