DTIC ADA477863: Orcas in Puget Sound

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by  Defense Technical Information Center

Technical Report 2007-01
Orcas in
Puget Sound
Prepared in support of the Puget Sound Nearshore Partnership
Birgit Kriete
Orca Relief

Valued Ecosystem Components Report Series
The Puget Sound Nearshore Partner- Brennan, J.S. 2007. Marine Riparian Vegetation Communi-
ship (PSNP) has developed a list of ties of Puget Sound. Puget Sound Nearshore Partnership
valued ecosystem components (VECs). Report No. 2007-02. Published by Seattle District, U.S.
The list of VECs is meant to represent a Army Corps of Engineers, Seattle, Washington.
cross-section of organisms and physical
Buchanan, J.B. 2006. Nearshore Birds in Puget Sound. Puget
structures that occupy and interact with
Sound Nearshore Partnership Report No. 2006-05. Pub-
the physical processes found in the near-
lished by Seattle District, U.S. Army Corps of Engineers,
shore. The VECs will help PSNP frame
Seattle, Washington.
the symptoms of declining Puget Sound
nearshore ecosystem integrity, explain Dethier, M.N. 2006. Native Shellfish in Nearshore Ecosys-
how ecosystem processes are linked to ecosystem outputs, tems of Puget Sound. Puget Sound Nearshore Partnership
and describe the potential benefits of proposed actions in Report No. 2006-04. Published by Seattle District, U.S.
terms that make sense to the broader community. A series Army Corps of Engineers, Seattle, Washington.
of “white papers” was developed that describes each of the
Eissinger, A.M. 2007. Great Blue Herons in Puget Sound.
VECs. Following is the list of published papers in the series.
Puget Sound Nearshore Partnership Report No. 2007-06.
All papers are available at www.pugetsoundnearshore.org.
Published by Seattle District, U.S. Army Corps of Engineers,
Seattle, Washington.
Fresh, K.L. 2006. Juvenile Pacific Salmon in Puget Sound.
Puget Sound Nearshore Partnership Report No. 2006-06.
Published by Seattle District, U.S. Army Corps of Engineers,
Seattle, Washington.
Johannessen, J. and A. MacLennan. 2007. Beaches and
Bluffs of Puget Sound. Puget Sound Nearshore Partner-
ship Report No. 2007-04. Published by Seattle District, U.S.
Army Corps of Engineers, Seattle, Washington.
Kriete, B. 2007. Orcas in Puget Sound. Puget Sound Near-
shore Partnership Report No. 2007-01. Published by Seattle
District, U.S. Army Corps of Engineers, Seattle, Washington.
Leschine, T.M. and A.W. Petersen. 2007. Valuing Puget
Sound’s Valued Ecosystem Components. Puget Sound
Nearshore Partnership Report No. 2007-07. Published
by Seattle District, U.S. Army Corps of Engineers, Seattle,
Washington.
Mumford, T.F. 2007. Kelp and Eelgrass in Puget Sound.
Puget Sound Nearshore Partnership Report No. 2007-05.
Published by Seattle District, U.S. Army Corps of Engineers,
Seattle, Washington.
Penttila, D. 2007. Marine Forage Fishes in Puget Sound.
Puget Sound Nearshore Partnership Report No. 2007-03.
Published by Seattle District, U.S. Army Corps of Engineers,
Seattle, Washington.
Front and back covers: Orcas in Puget Sound (courtesy of
Washington Sea Grant)
ii Orcas in Puget Sound
Contents
Executive Summary ....................................................................................................................................v
Preface .......................................................................................................................................................1
Nearshore Habitat Requirements . ...........................................................................................................2
Ecosystem Processes Supporting Habitat Attributes ...........................................................................16
Major Gaps / Critical Uncertainties .........................................................................................................18
Conclusions: Key Measures for Orca Restoration.................................................................................18
References ................................................................................................................................................19
Technical Report 2007-01 Puget Sound Nearshore Partnership iii
Acknowledgments
First and foremost, thanks go to Dr. Megan Dethier and The Puget Sound Nearshore Partnership Steering
the Nearshore Science Team of PSNERP for giving me Committee initiated the concept of this paper and the
the opportunity to write this paper. Valuable unpublished others in this series. The Nearshore Partnership Project
papers and graphs were provided by Peter Olesiuk of Management Team (PMT) — Tim Smith, Bernie Hargrave,
Department off Fisheries and Oceans (DFO), Canada. Curtis Tanner and Fred Goetz — oversaw production of
the papers. The Nearshore Science Team (NST) played a
number of roles: they helped develop conceptual models for
Recommended bibliographical citation:
each valued ecosystem component (VEC), in collaboration
Kriete, B. 2007. Orcas in Puget Sound. Puget Sound Near- with the authors; individual members were reviewers for
shore Partnership Report No. 2007-01. Published by Seattle selected papers; and members were also authors, including
District, U.S. Army Corps of Engineers, Seattle, Washington. Megan Dethier, Tom Mumford, Tom Leschine and Kurt
Fresh. Other NST members involved were Si Simenstad,
Available at www.pugetsoundnearshore.org.
Hugh Shipman, Doug Myers, Miles Logsdon, Randy
Shuman, Curtis Tanner and Fred Goetz.
The Nearshore Partnership organization is especially
grateful for the work done by series science editor Megan
Dethier, who acted as facilitator and coach for the authors
and liaison with the NST and PMT. We also thank the U.S.
Army Corps of Engineers Public Affairs Staff — Patricia
Grasser, Dick Devlin, Nola Leyde, Casondra Brewster and
Kayla Overton — who, with Kendra Nettleton, assisted with
publication of all the papers in the series.
Finally, the Nearshore Partnership would like to thank the
Washington Sea Grant Communications Office — Marcus
Duke, David Gordon, Robyn Ricks and Dan Williams —
for providing the crucial editing, design and production
services that made final publication of these papers possible.
This report was supported by the Puget Sound Nearshore
Ecosystem Restoration Project through the U.S. Army
Corps of Engineers and Washington Department of Fish
and Wildlife.
For further information or printed copies of this report,
contact Curtis Tanner, Local Project Manager, Puget Sound
Nearshore Ecosystem Restoration Project, Washington
Department of Fish and Wildlife, 600 Capital Way North,
Olympia, Washington 98501-1091.
[email protected].
To download PDF files of this and other reports in the
series, visit our Web site at www.pugetsoundnearshore.org.
iv Orcas in Puget Sound
Executive Summary
The stock of southern resident killer whales (SRKW) in Much biological information is available on these popula-
the eastern North Pacific declined by almost 20% in a tions, due to 30 years of research and the animals’ high
five-year period to fewer than 80 individuals in 2001. Data visibility and individual identification. These top predators
suggest that the SRKW population might have previously use nearshore locations for foraging and travel and are very
numbered as many as 200 individuals during the 1800s, susceptible to human disturbances and ecosystem decline.
prior to human impact. The recent decline led the National Their long life expectancy and position at the top of the
Oceanic and Atmospheric Administration (NOAA) to list food web contribute to the whales’ accumulation of toxins,
this resident group of orca as endangered under the Endan- which can be dated back to the 1930s. Decreased reproduc-
gered Species Act (ESA) in November 2005. A combination tive success has also been linked with reduced prey avail-
of natural factors, including El Niño and La Niña but largely ability.
reductions in prey resources, disturbance from vessel traffic,
The variety of human threats currently impacting orcas in-
and toxins, most likely contributed to the whales’ decline.
cludes ecosystem deterioration, direct and indirect effects of
These factors cumulatively affect resident and transient
contaminants on both prey and orca, ‘loving the whales to
whales’ survival to the present. Data on previous numbers of
death’ by the constant presence of whale watch boats much
transient killer whales are not available.
of the year, and historical decline of salmon populations
Ecologically, economically and recreationally, southern caused by habitat disturbance, overharvesting and inappro-
resident and transient killer whales have become greatly priate hatchery practices. Removal of nearly 40 percent of
important to the local nearshore environment. Economi- the SRKW population, as well as a number of transient or-
cally, whale watching in the San Juan Islands alone has cas, during the late 1960s and early 1970s for public display
become a $10 million industry in the last few years. More also harmed the populations. While there is potential to
than 500,000 visitors participate in whale watching on com- restore the whales’ environment by turning around various
mercial vessels in the nearshore waters of Washington and damaged processes, this will take decades to achieve. Local
British Columbia annually, not including visitors on an es- and regional efforts, as well as international agreements and
timated 3,000 to 8,000 private vessels (The Whale Museum laws, regarding toxics disposal will be necessary to achieve
2006). this goal.
Technical Report 2007-01 Puget Sound Nearshore Partnership v
vi Orcas in Puget Sound
Preface
The southern resident population of orca is an extremely population was removed for display in aquaria worldwide.
valuable resource to the Puget Sound area. Ecologically, Orcas became a well-known and much-loved species.
the species inhabits the top of the food chain and serves as a
Over the last 18 years, killer whales have been turned into
sentinel species for environmental health. Being a top car-
‘superstars’ and nowadays draw in tourists and research-
nivore, resident killer whales consume primarily Chinook
ers as well as local, national, and international businesses
salmon, a smaller percentage of other local salmon species
benefiting the local economy. They have become of great
and some bottom fish, while transient orcas feed almost en-
importance economically and recreationally. The status of
tirely on marine mammals.
the species, and the emotional bond that humans have de-
Historically, killer whales were of cultural importance to na- veloped with killer whales, due to similarities in social orga-
tive people but of no recreational or commercial importance nization and culture and through movies, guarantees media
to settlers. Rather, the whales were feared and killed because attention. Annually, approximately 500,000 visitors watch
of their competition with the fishing industry for salmon. this population of whales from boats in nearshore local wa-
This view on orcas changed in the late 1960s and early 1970s ters (The Whale Museum 2006).
when, within four years, approximately 40 percent of the
Many factors affect the health of free-ranging killer whales
noise
genetics
stress
nutrition
immunotoxic
contaminants
age
pathogens
reproductive sex
cycle
Ross et al 2004
Technical Report 2007-01 Puget Sound Nearshore Partnership 1
Nearshore Habitat Requirements
Distribution General Life History Description
Two distinct types of killer whales (Orcinus orca, Linnaeus Resident killer whales are long-lived, highly social marine
1758) are commonly found in Puget Sound: the southern mammals that live in stable matrilineal pods throughout
resident (fish eating) and the transient (marine mammal eat- their entire lives (Baird 2000, Ford et al. 2000, Ford 2002,
ing). A third type of killer whale was recognized in the late Ford and Ellis 2002). Two juveniles who became separated
1980s and described as the offshore killer whale population from their pods, A73 and L98, are considered anomalies.
(Ford et al. 1992, 1994, Walters et al. 1992). Offshore orca Southern resident group sizes vary among the three pods:
and northern residents rarely enter the protected waters of K-pod is the smallest with 18 whales, J-Pod follows with 24
Puget Sound (Wiles 2004) and are therefore not extensively individuals, and L-Pod is the largest group of the southern
described in this paper. resident population with 41 animals (K. Balcomb, pers.
comm., 2006). The pods aggregate temporarily through-
The southern resident killer whale (SRKW) community con-
out the year, and are often seen traveling and socializing
sists of three pods, known as J, K, and L pods, numbering
together (Dahlheim and Heyning 1999, Baird 2000, Ford et
86 whales as of the end of October 2006 (K. Balcomb, pers.
al. 2000). Breeding must also take place during the social
comm., Center for Whale Research 2006). All reside in the in-
encounters, even though it has never reliably been observed
land waters of Washington State and southern British Colum-
in the wild. Pods have individual vocal dialects, as well as
bia (Juan de Fuca Strait, Puget Sound and the Strait of Georgia)
sharing some calls with other pods (Ford 1989).
for a considerable time of the year, predominantly from early
spring until late fall (Ford and Ellis 2002, Krahn et al. 2002) Transient killer whales show much less stability in their so-
(Figure 1). Most often the resident pods are seen in Haro cial groupings. Wiles (2004) states that at least 225 transient
Strait, along the west side of San Juan Island, and in the south- killer whales have been photo-identified in Washington,
ern part of Georgia Strait, Boundary Passage, the southern Gulf British Columbia and Alaska, with an estimate of 300-400
Islands and the eastern end of Juan de Fuca Strait (Heimlich- transients for the entire North American west coast. About
Boran 1988, Felleman et al. 1991, Olsen 1998, Ford et al. 2000, one-third of this population has been observed in Washing-
The Whale Museum 2006) (Figures 1 and 2). ton state. Due to transient whales’ irregular occurrences, it
is difficult to determine deaths over time; a complete num-
During early autumn, southern resident pods, especially
ber of transients and accurate population assessment cannot
J pod, expand their routine movements into Puget Sound
be given (Baird 2001a).
proper; probably to take advantage of Chinook and chum
salmon runs (Osborne 1999). In recent years, it has become Transient pods are smaller in number than resident pods,
fairly common for K and L pods to feed in the sound. The ranging from 1 to 4 whales per pod (Baird and Dill 1996,
resident pods are seen in Admiralty Inlet (Whidbey Island) Ford and Ellis 1999, Baird and Whitehead 2000). They also
and Puget Sound (Osborne 1999) (Figure 2), as well as along live in fairly stable maternal groups, generally consisting of
the Oregon and California coasts. All three pods travel out- an adult female and one or two of her offspring. However,
side the inshore waters throughout the year, venturing out dispersal of members from their natal pods is common.
to the west side of Vancouver Island and the outer coast of The smaller numbers of whales in transient groups very
the Olympic Peninsula. During the late fall to late winter, the likely aid the whales in detecting and capturing their patch-
SRKW travel as far south as Monterey, California, and north ily distributed food, which includes seals, sea lions, harbor
to the Queen Charlotte Islands, British Columbia. SRKWs and Dall’s porpoises, minke whales and particularly harbor
generally stay within 50 km of the shore (Ford et al. 2005a) seals (Hoyt 1990, Jefferson et al. 1991, Dahlheim and Heyn-
(Figures 2 and 3). ing 1999, Baird and Dill 1996, Ford et al. 1998). A smaller
transient pod minimizes competition and maximizes in-
Transient orcas’ distribution encompasses a much larger
dividual energy intake (Baird and Dill 1996, Ford and Ellis
geographic area, ranging from Los Angeles, California, to
1999, Baird and Whitehead 2000), while the larger numbers
Icy Strait and Glacier Bay in Alaska (Goley and Straley 1994,
in a resident pod probably help in finding schools of fish
Ford and Ellis 1999, Baird 2001a, Barrett-Lennard and Ellis
(Ford et al. 2000).
2001) (Figure 4a). Wiles (2004) reports that most transients
along the Puget Sound and Vancouver Island shorelines are Genetic evidence (Stevens et al. 1989, Hoelzel et al. 1998,
recorded during the summer and early fall, which coincides Barrett-Lennard 2000, Barrett-Lennard and Ellis 2001) sug-
with seal pupping and more search effort. gests that transient and resident killer whale populations in
the Pacific Northwest have been isolated from each other
Offshore killer whales’ distribution ranges from Los Angeles,
for thousands of years (Bigg et al. 1987, Hoelzel et al. 1998).
California, to the eastern Aleutian Islands (Ford and Ellis
Genetic and morphological differences between northern
1999) (Figure 4b). They generally stay more than 15 km off-
and southern resident orca in Washington and British Co-
shore (Krahn et al. 2002). This group’s distribution is poorly
lumbia waters suggest that these two populations are repro-
understood due to infrequent observations.
ductively isolated. While both types of orca belong to the
2 Orcas in Puget Sound
Figure 1. Typical distribution and relative occurrence of Southern Resident Killer Whales in northern Puget
Sound during June, which is also representative of overall spring-fall occurrence (The Whale Museum 2006).
same species and share considerable overlap in their range, Ellis 2001). Most births take place between October and
mitochondrial DNA sequence data indicate that resident March (Olesiuk et al. 1990). Calving intervals were estimat-
haplotypes are divergent from transient types. Southern ed to range from 4.9 to 7.7 years (Olesiuk et al. 1990, Krahn
residents satisfy all of the criteria necessary to delineate a et al. 2002, 2004, Matkin et al. 2003).
separate stock under the Marine Mammal Protection Act
Since annual identification of each individual resident orca
(MMPA) (Krahn et al. 2002), while sharing similarities with
has been done for the last 32 years, long-term population
other populations of killer whales in behavior, morphology
dynamics of this group of whales are known. Despite this
and ecology. While no subspecies are recognized, Krahn et
unusually large database, uncertainties persist because the
al. (2004) suggested that all resident orca in the northeast
studies only span about half the average lifetime of a female.
Pacific should be treated as a single unnamed subspecies,
As with other mammals, the SRKW population has differ-
separate from transient killer whales.
ences in survival with age, with relatively low early survival,
Offshore killer whales are morphologically similar to the high adult survival, and declining survival in older indi-
SRKW; i.e., their dorsal fins appear to be more rounded at viduals (Caughley 1966). Survival also differs between sexes.
the tip, and most saddle patches appear to be closed (Na- Olesiuk et al. (1990) determined that local females have an
tional Marine Mammal Lab unpubl. data). They do not mix average life expectancy of about 50 years, which may extend
with residents or transients. Hoelzel et al. (1998) showed to a maximum age of 80-90 years. The youngest known
that offshores are genetically more closely related to the female to give birth was 11 years old, while the mean age of
southern residents, yet are probably genetically isolated females at first birth was 15 years. On average, five viable
from local resident or transient orcas. Offshore orca groups calves (calves that survive to their first summer) are born to
ranging from 10 to 70 whales have been observed. a single female over her 25-year reproductive lifespan. Since
the mid 1990s, females’ average age of first birth has been
Genetic studies also indicate that local resident killer whales
observed to occur one year later in SRKW females, to 16
are polygamous, and males mate only with females outside
years of age (Olesiuk et al. 2005 and 2006).
their natal pod (Barrett-Lennard 2000, Barrett-Lennard and
Technical Report 2007-01 Puget Sound Nearshore Partnership 3