Fourth International Orca Symposium and Workshop - CEBC - CNRS

BEHAVIOR AND ECOLOGY OF KILLER WHALES IN MONTEREY BAY,
CALIFORNIA
Black N. 1 , Ternullo R. 2 , Schulman-Janiger A. 3 , Ellis G. 4 , Dahlheim M. 5 . 1,2 Peggy Stap
Monterey Bay Cetacean Project, P.O. Box 52001, Pacific Grove, CA 93950 Nyblack@aol.com 3
American Cetacean Society, Los Angeles 4 Canadian Department of Fisheries and Oceans 5 National
Marine Mammal Laboratory, NOAA.
INTRODUCTION AND BACKGROUND
Monterey Bay (36°N 122°W) is located along the central California coast within a
highly productive region of major upwelling. The Monterey Submarine Canyon is the most
prominent bathymetric feature within the Bay and beyond, allowing for unique opportunities
to study deep-water cetaceans in a near-shore environment.
Three known ecotypes (Residents, Transients, Offshore) of Killer Whales exist in the
eastern North Pacific, and all have been sighted in Monterey Bay. Each can be distinguished
by appearance and vocalizations at sea and have been differentiated genetically. Resident
whales, which are well studied in the Pacific Northwest, travel and feed in predictable areas
during summer months in inland waters of Washington state, Vancouver, B.C., and Alaska.
They prey primarily on fish, live in closely associated family groups, and are very vocal.
Transients in Monterey Bay are part of the west coast community of about 300 whales that
range from southern California to southeast Alaska, prey on marine mammals, travel in
relatively small groups, travel over long ranges, and are often vocally quiet. The Offshore
type is least known, often travels in large groups of over 100 animals, many have nicked fins,
and probably prey on fish and squid. A fourth type that has occurred periodically in Monterey
Bay is the “LA Pod”. No genetic samples have been obtained for this group, and they have
never been seen in association with any other type.
METHODS
Our methods for reaching the killer whales included use of 55-70’ powerboats and a 22’
inflatable. The study period for this report extended from 1987 through 2002. Our effort was
both opportunistic, on whale watch vessels, and dedicated searches for killer whales on
special projects funded by the BBC and National Geographic Society and on our own vessels
throughout the study period. In addition a large sighting network is in place where various
vessels reported killer whale sightings. Our research methods included photo-identifying
individual whales and documenting their behavior, sighting locations and local movement
patterns as well as collaborating with other scientists in the Pacific to document re-sightings
in other areas.
RESULTS AND DISCUSSION
Transients were most frequently sighted (223 sightings with photos from 1987-2002)
and were highly associated with the canyon edge. Offshore (18 sightings) and LA Pod (9
sightings) sightings were found along canyon edges and also in inshore shallower waters.
Known prey of each killer whale type when feeding in Monterey Bay included for
Transients: Gray whale calves, California sea lions, Harbor Seals, Elephant Seals, Dall’s
Porpoise, Pacific White-Sided Dolphins, Long Beaked Common Dolphin, and seabirds;
Offshores: salmon, small schooling fish, and blue shark; Residents: Chinook salmon; LA Pod:
FOURTH INTERNATIONAL ORCA SYMPOSIUM AND WORKSHOPS
SEPTEMBER 23-28 2002, CEBC-CNRS, France
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