Fourth International Orca Symposium and Workshop - CEBC - CNRS

Given this, years between calves ranged from 3 (n=1) to 12 (n=1) years; and in between: 4
years (n=1), 5 yr (n=1), 6 yr (n=2), 7 yr (n=3), 8 yr (n=3), 9 yr (n=1). Compared to other
populations this rate appeared low and could be related to high levels of PCB’s found in this
group of killer whales.
Association pattern analysis indicated that transient whales occurred in 18 core groups
of frequently sighted whales (up to 36 if infrequently sighted whales were included). Core
groups were usually composed of 2-4 reproductive females with juveniles and calves, and
some with one sprouter male or adult male. A few groups were composed of male pairs.
These core groups of individuals were sighted together on more than 80% to 100% of the
time. Two or more of these core groups joined together for temporary associations, especially
during spring months while searching for and hunting Gray Whale calves. Three welldocumented
young males were sighted over a period of 10 and 11 years and are now sprouters
and young adults. All still travel with their probable mothers with estimated current ages of 15
to 19 years.
This study represents the only long-term database for Killer Whales south of
Washington State but part of the same population as whales to the north. Monterey Bay is a
key area for detailed studies of the three known ecotypes and possibly five, as the ranges of
these types may overlap in the region.
Study Area
2000
1500
Depth in Meters
Mont erey Submarine Canyon
5 km
Santa Cr uz
Car mel Cany on
122°20'W 122°00'W
N
n=140 transient sightings
n=12 offshore sightings
n=9 LA pod sightings
1000
500
200
Pt.
Pinos
Hopkins
Cypr ess Pt.
Pt. Lobos
100 50
Gr anite Canyon
Pt. Sur
37°00'N
Monter ey
Moss
Landing
36°40'
N
36°20'N
Figure 1. Distribution of Killer Whale types in Monterey Bay.
FOURTH INTERNATIONAL ORCA SYMPOSIUM AND WORKSHOPS
SEPTEMBER 23-28 2002, CEBC-CNRS, France
42