Conservation Genetics of the Killer Whale Enabling the Legislative Protection of an Endangered Distinct Population Segment (DPS)
Submitting InstitutionUniversity of Durham
Unit of AssessmentBiological Sciences
Summary Impact TypeEnvironmental
Research Subject Area(s)
Environmental Sciences: Environmental Science and Management
Biological Sciences: Ecology
Summary of the impact
Listing an endangered DPS under US law (governed by the Endangered
Species Act, ESA, of 1973) requires the use of genetic markers to assess
the extent of reproductive isolation, direction and pattern of gene flow,
and effective size of the DPS under assessment. Professor Hoelzel's group
provided these essential data from work in multiple peer-review
publications, and in a commissioned report in 2004 in support of a
successful petition by the National Marine Fisheries Service (NMFS) to
protect the killer whale population residing in the inland waters of
Washington State, USA, after it was shown to have declined by 20% in 10
years (Krahn et al. 2004; see volume 79, No.222 of the Federal Register
for DPS listing). This formed the foundation for on-going impact on policy
and regulation between 2008 and the present, including support in response
to petitions filed in 2012 and 2013 (see testimonial from the Branch
Chief, NOAA Fisheries). Killer whale sustainability in this region
reflects general ecosystem health and supports an economically important
Research led by Professor Hoelzel in the School of Biological and
Biomedical Sciences has assessed the units of management and conservation
for killer whales (Orcinus orca) worldwide. The killer whale is a
top predator species that forms long-term stable social groups (`pods').
These pods are matrifocal in organisation, and so the founding of regional
populations will be by a group of individuals related to each other along
the matriline. Details of kinship within and among these groups were
determined by research conducted in Prof. Hoelzel's group (Pilot et al.
2010), and showed that both males and females often remained in
association with maternal kin, with mating apparently happening during
temporary associations with other pods. The impact on the genetic
structure of populations was reported earlier when regional populations
were shown to have fixed matriline marker (mitochondrial DNA) genotypes,
and to be differentiated from each other (Hoelzel et al. 1998, 2002,
2007). Each social group specializes in prey choice, and this served as an
apparent boundary to gene flow such that populations of different foraging
strategists (marine mammal eating compared to fish eating) in the same
geographic region (`sympatric' populations) were found to be genetically
differentiated from each other (Hoelzel et al 1998). At the same time, it
was shown that there was a pattern of genetic isolation by geographic
distance within an `ecotype' (Hoelzel et al. 2002). It was also shown that
genetic diversity for the species as a whole was low, suggesting an
historical population bottleneck, but not one likely influenced by
anthropogenic factors, as it occurred an estimated 150,000 years ago
(Hoelzel et al. 1998, 2002). The importance of group activities towards
efficient prey capture in the `southern resident', fish-eating population
of killer whales in Washington State waters was demonstrated (Hoelzel
1993), indicating the importance of group composition and stability.
Evidence for a population decline and the suggestion that some animals may
have starved promoted concern for the future of the southern resident
population in particular. It was also demonstrated by Prof. Hoelzel's
group that the whales in this population had changed their behaviour in
response to anthropogenic disturbance - the increasing number of boats
associated with the whale-watching industry in this region (Foote et al.
2004). The change was manifest in `anti-masking' behaviour such that
beyond an apparent threshold level, increasing numbers of boats in
association with the whales led to them increasing the duration of their
vocal calls. These data were later reviewed in support of new regulations
(2010 Environmental Assessment; RIN 0648-AV15, pg. 3-28) governing vessel
traffic in the vicinity of this population of killer whales. Although
there was evidence for ongoing gene flow at a low level, various analyses
showed that the southern resident population was differentiated from all
other local populations, and that the rate of gene flow was low enough for
the population to be designated a DPS (Hoelzel et al 1998, 2002, 2007).
These data were summarised in a report commissioned by NMFS for the ESA
listing procedure (Hoelzel 2004), and both the report and supporting
papers were cited extensively by the proposers in support of their
petition for DPS listing and in support of later policy reviews and
References to the research
Papers on population genetics and behaviour cited in petition and
review to support case for listing
Hoelzel, A.R., Hey, J., Dahlheim, M.E., Nicholson, C., Burkanov, V. &
Black, N. 2007. Evolution of Population Structure in a Highly Social Top
Predator, the Killer Whale. Mol. Biol. Evol. 24:1407-1415
Hoelzel, A.R., Natoli, A., Dahlheim, M., Olavarria, C., Baird, R.W.,
Black, N. 2002. Low world-wide genetic diversity in the killer whale (Orcinus
orca); Implications for demographic history. Proc. Royal Soc. B
Hoelzel, A.R., Dahlheim. M. and Stern, S.J. 1998. Low genetic variation
among killer whales (Orcinus orca) in the eastern North Pacific,
and genetic differentiation between foraging specialists. J. Hered.
Hoelzel, A.R. 1993. Foraging behaviour and social group dynamics in Puget
Sound killer whales. Animal Behaviour, 45:581-591.
Report commissioned by BRT in support of petition:
Hoelzel, A. R. 2004. Report on killer whale population genetics for the
BRT review on the status of the southern resident population. Unpublished
report to the National Marine Fisheries Service. 27 pg. (supported by NMFS
Further studies supporting case that were in support of ongoing
conservation efforts - evidence of ongoing impact (1 example):
Foote, A.D., Osborne, R.W. & Hoelzel, A.R. 2004. Killer whale
anti-masking response to whale-watcher boat noise. Nature 428:
Pilot, M., Dahlheim, M.E. & Hoelzel, A.R. 2010. Social cohesion among
kin, gene flow without dispersal and the evolution of population genetic
structure in the killer whale (Orcinus orca). J. Evol. Biol.
Details of the impact
The primary impact of this study comes from on-going efforts to protect
the `Southern Resident' killer whale population in Washington State
waters. Long-term data suggesting a population decline convinced local
management authorities that protection under the Endangered Species Act
was necessary. Supported by Prof Hoelzel's research establishing genetic
isolation (e.g. Hoelzel et al. 1998, 2002), the Southern Resident
community was designated as a Distinct Population Segment in 2005 (the
smallest division of a species permitted to be protected under the US
Endangered Species Act), which led to the group being listed as an
endangered species by the National Marine Fisheries Service (NOAA
Fisheries). The listing process is intentionally long and difficult, with
relatively few applications succeeding. Prof Hoelzel's research was vital
in the designation of the killer whale as endangered, with his work
"important to the original listing" and continuing "to inform status
updates and response to petitions under the ESA" (NOAA testimonial). The
initial petition in 2001 cited Prof. Hoelzel's work 23 times, the status
reviews in 2002 and 2004 cited Prof. Hoelzel's work 12 and 26 times
respectively. The ESA listing provided the "foundation" for a variety of
organisations to develop policies and action plans to help recovery of the
killer whale DPS. Prof Hoelzel's research has provided academic evidence
in support of the `Determination of Critical Habitat' and a `Species
Recovery Plan' that are legally required following the listing process,
and including support for legislation providing new regulations on vessel
activities approved and established in 2011.
The killer whale is an alpha predator species that has a key impact on
local species communities and ecosystems, as the primary predator of other
marine mammals, and an important predator of fish species. It is also a
high profile flagship species of great interest to the public through
exposure in the media, `whale-watching' businesses, and at aquarium parks.
At the end of 2012 there were only 84 whales in the Southern Resident
population, which supports a significant whale-watching industry on the
Washington coast (76 boats and 500,000 passengers per year in 2006 at $100
per passenger; Oliver 2008). According to a report from 2001 (Hoyt 2001)
the overall value of the local whale watching industry was assessed as
$66.2M annually and wildlife watching (whales and other animals) in
Washington State produced an annual economic output of $1.78BN,
maintaining over 21,000 jobs (more than Microsoft and almost as many as
In 2008 NOAA completed a Recovery Plan identifying actions needed for the
conservation and recovery of the Southern Residents (NMFS 2008). Again
influenced by Prof Hoelzel's work, this plan was reviewed in 2011. Since
the species was listed, "a variety of federal, state, non-profit, and
local organisations implemented conservation actions to benefit the
whales, their salmon prey, and the ecosystem" (NOAA testimonial). Results
from this include:
- NOAA, the Environmental Protection Agency and the Washington
Department of Ecology are working to reduce pollution in the Puget
Sound, such as reducing agricultural run-off and examining the impacts
of flame retardants (PBDEs) on the killer whales (NOAA testimonial).
- An oil spill response plan has been specifically developed for killer
whales in the event of a major spill in Washington and Oregon State (Oil
Spill Response and Killer Whales).
- Noise reduction regulations were enacted in 2011 to reduce disturbance
from the significant fishing and whale-watching industry (Be Whale
Wise). Vessels are now prohibited from approaching within 200 yards of a
killer whale and must not park in front of their path when in the inland
waters of Washington State. This work was supported in part by data from
Prof. Hoelzel's lab on the quantifiable impact of boat noise on the
behaviour of affected whales (Foote et al. 2004).
Prof Hoelzel's work has also informed the submission of recent petitions
calling for changes to the status of the southern resident killer whale
under the Endangered Species Act. For example, in August 2012 a petition
submitted by the Pacific Legal Foundation, on behalf of the Center for
Environmental Science Accuracy and Reliability, Empresas Del Bosque, and
Coburn Ranch, called for the Southern Residents to be delisted under the
ESA. Both the petition and the resolution of the case (rejecting
delisting, consistent with comments provided by Prof. Hoelzel) "relied
heavily" on a paper from Prof Hoelzel's lab (Pilot et al. 2010).
Prof Hoelzel has been thanked repeatedly by stakeholders involved in
researching and protecting the killer whales, for "numerous contributions
on killer whale genetics and valuable insights into killer whale stock
structure" (NOAA testimonial).
Sources to corroborate the impact
Center for Biological Diversity (2001) Petition to list the southern
resident killer whale (Orcinus orca) as an endangered species under
the endangered species act.
Krahn, M.M., et al. (2002) Status review of Southern Resident killer
whales (Orcinus orca) under the Endangered Species Act. U.S. Dept.
Commerce, NOAA Tech. Memo. NMFS-NWFSC-54, 133 p.
Krahn, M.M., M.J. Ford, W.F. Perrin, P.R. Wade, R.P. Angliss, M.B.
Hanson, B.L. Taylor, G.M. Ylitalo, M.E. Dahlheim, J.E. Stein, and R.S.
Waples (2004) 2004 Status review of Southern Resident killer whales (Orcinus
orca) under the Endangered Species Act. U.S. Dept. Commerce, NOAA
Tech. Memo. NMFSNWFSC-62, 73 p.
50 CFR Part 224 [Docket No. 041213348-5285-02; I.D. 110904E] RIN
0648-AS95 Endangered and Threatened Wildlife and Plants: Endangered Status
for Southern Resident Killer Whales. Federal Register, Vol 70, No. 222/
Friday November 18, 2005.
NMFS report (2006) Designation of critical habitat for southern resident
Oliver (2008) Recovery plan for southern resident killer whales (Orcinus
orca). NOAA NMFS report: http://www.nwr.noaa.gov/Marine-Mammals/Whales-Dolphins-Porpoise/Killer-Whales/ESA-
50 CFR Part 224 [Docket No. 070821475-81493-01] RIN 0648-AV15 Protective
Regulations for Killer Whales in the Northwest Region Under the Endangered
Species Act and Marine Mammal Protection Act. Federal Register, Vol. 74,
No. 144, Wednesday, July 29, 2009.
RIN 0648-XV19 Endangered and Threatened Species; Initiation of 5-Year
Review for Southern Resident Killer Whales. Federal Register, Vol. 75, No.
65, Tuesday, April 6, 2010.
50 CFR Part 224 [Docket No. 070821475-91169-02] RIN 0648-AV15 Protective
Regulations for Killer Whales in the Northwest Region Under the Endangered
Species Act and Marine Mammal Protection Act. Federal Register, Vol. 76,
No. 72, Thursday, April 14, 2011.
NMFS (2011) 5-year review: summary and evaluation. http://www.nwr.noaa.gov/Marine-Mammals/Whales-Dolphins-Porpoise/Killer-Whales/ESA-Status/upload/KW-review-2011.pdf
Testimonial from the Branch Chief, Protected Resources Division, NOAHH