Alaska Marine Mammal Stock Assessments, 2014

313 Pages·2015·9.44 MB·English

NOAA Technical Memorandum NMFS-AFSC-301
doi:10.7289/V5NS0RTS
Alaska Marine Mammal
Stock Assessments, 2014
B. M. Allen and R. P. Angliss
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration

National Marine Fisheries Service

Alaska Fisheries Science Center

June 2015
NOAA Technical Memorandum NMFS
The National Marine Fisheries Service's Alaska Fisheries Science Center uses
the NOAA Technical Memorandum series to issue informal scientific and
technical publications when complete formal review and editorial processing
are not appropriate or feasible. Documents within this series reflect sound
professional work and may be referenced in the formal scientific and technical
literature.
The NMFS-AFSC Technical Memorandum series of the Alaska Fisheries
Science Center continues the NMFS-F/NWC series established in 1970 by the
Northwest Fisheries Center. The NMFS-NWFSC series is currently used by
the Northwest Fisheries Science Center.
This document should be cited as follows:
Allen, B. M., and R. P. Angliss. 2015. Alaska marine mammal stock
assessments, 2014. U.S. Dep. Commer., NOAA Tech. Memo. NMFS­
AFSC-301, 304 p. doi:10.7289/V5NS0RTS.
Document available: http://www.afsc.noaa.gov/Publications/AFSC-TM/NOAA -TM-AFSC-301.pdf.
Reference in this document to trade names does not imply endorsement by
the National Marine Fisheries Service, NOAA.
Cover photo: Fin whale photographed during the AFSC's Aerial Surveys of Arctic Marine Mammals (ASAMM) surveys
in the Chukchi Sea, September 2012. Photographer: Allison Henry (AFSC-NMML), NMFS Permit No.
14245, Funded by BOEM (IA Contract No. M11PG00033).
NOAA Technical Memorandum NMFS-AFSC-301
doi:10.7289/V5NS0RTS
Alaska Marine Mammal
Stock Assessments, 2014
by
B. M. Allen and R.P. Angliss
with contributions from
P. R. Wade, J. M. Breiwick, L. W. Fritz, M. C. Ferguson, M. E. Dahlheim, J. M. Waite, R. R. Ream,
M. F. Cameron, J. M. London, P. L. Boveng, E. L. Richmond, K. E. W. Shelden, B. S. Fadely, R. C. Hobbs,
R. G. Towell, S. P. Dahle, P. J. Clapham, V. T. Helker, A. S. Kennedy, G. R. Lewis, S. A. Mizroch,
and the Communications Program of the Alaska Fisheries Science Center
Alaska Fisheries Science Center
7600 Sand Point Way NE
Seattle, WA 98115-6349
www.afsc.noaa.gov
U.S. DEPARTMENT OF COMMERCE
Penny S. Pritzker, Secretary
National Oceanic and Atmospheric Administration
Kathryn D. Sullivan, Under Secretary and Administrator
National Marine Fisheries Service
Eileen Sobeck, Assistant Administrator for Fisheries
June 2015
This document is available to the public through:
National Technical Information Service
U.S. Department of Commerce
5285 Port Royal Road
Springfield, VA 22161
www.ntis.gov
PREFACE
On 30 April 1994, Public Law 103-238 was enacted allowing significant changes to provisions within the
Marine Mammal Protection Act (MMPA). Interactions between marine mammals and commercial fisheries are
addressed under three new sections. This new regime replaced the interim exemption that has regulated fisheries-
related incidental takes since 1988. Section 117, Stock Assessments, required the establishment of three regional
scientific review groups to advise and report on the status of marine mammal stocks within Alaska waters, along the
Pacific Coast (including Hawaii), and the Atlantic Coast (including the Gulf of Mexico). This report provides
information on the marine mammal stocks of Alaska under the jurisdiction of the National Marine Fisheries Service.
Each stock assessment includes, when available, a description of the stock’s geographic range, a minimum
population estimate, current population trends, current and maximum net productivity rates, optimum sustainable
population levels and allowable removal levels, and estimates of annual human-caused mortality and serious injury
through interactions with commercial fisheries and subsistence hunters. These data will be used to evaluate the
progress of each fishery towards achieving the MMPA’s goal of zero fishery-related mortality and serious injury of
marine mammals.
The Stock Assessment Reports should be considered working documents, as they are updated as new
information becomes available. The Alaska Stock Assessment Reports were originally developed in 1995 (Small
and DeMaster 1995). Revisions have been published for the following years: 1996 (Hill et al. 1997), 1998 (Hill and
DeMaster 1998), 1999 (Hill and DeMaster 1999), 2000 (Ferrero et al. 2000), 2001 (Angliss et al. 2001), 2002
(Angliss and Lodge 2002), 2003 (Angliss and Lodge 2004), 2005 (Angliss and Outlaw 2005), 2006 (Angliss and
Outlaw 2007), 2007 (Angliss and Outlaw 2008), 2008 (Angliss and Allen 2009), 2009 (Allen and Angliss 2010),
2010 (Allen and Angliss 2011), 2011 (Allen and Angliss 2012), 2012 (Allen and Angliss 2013), and 2013 (Allen
and Angliss 2014). Each Stock Assessment Report is designed to stand alone and is updated as new information
becomes available. The MMPA requires stock assessment reports to be reviewed annually for stocks designated as
strategic, annually for stocks where there is significant new information available, and at least once every 3 years for
all other stocks. New information for all strategic stocks (Steller sea lions, northern fur seals, bearded seals, ringed
seals, Cook Inlet beluga whales, AT1 transient killer whales, harbor porpoises, sperm whales, humpback whales, fin
whales, North Pacific right whales, and bowhead whales) was reviewed in 2013-2014. This review, and a review of
other stocks, led to the revision of the following stock assessments for the 2014 document: Steller sea lions (western
and eastern U.S. stocks), northern fur seal, spotted seal, bearded seal, ringed seal, ribbon seal, beluga whales
(Beaufort Sea, eastern Chukchi Sea, eastern Bering Sea, Bristol Bay, and Cook Inlet stocks), AT1 transient killer
whale, harbor porpoises (southeast Alaska, Gulf of Alaska, and Bering Sea stocks), sperm whale, western and
central North Pacific stocks of humpback whales, fin whale, eastern North Pacific right whale, and bowhead whale.
The stock assessment reports for all stocks, however, are included in this document to provide a complete reference.
Those sections of each stock assessment report containing significant changes are listed in Appendix Table 1. The
authors solicit any new information or comments which would improve future stock assessment reports.
The U.S. Fish and Wildlife Service (USFWS) has management authority for polar bears, sea otters, and
walrus. Copies of the stock assessments for these species are included in this NMFS Stock Assessment Report for
your convenience.
Ideas and comments from the Alaska Scientific Review Group (SRG) have significantly improved this
document from its draft form. The authors wish to express their gratitude for the thorough reviews and helpful
guidance provided by the Alaska Scientific Review Group members: Karl Haflinger, Lloyd Lowry (Chair from 2012
to present), Beth Mathews, Craig Matkin, Mike Miller, Grey Pendleton, Robert Small, Kate Stafford, Robert
Suydam, David Tallmon, and Kate Wynne.
The information contained within the individual stock assessment reports stems from a variety of sources.
Where feasible, we have attempted to utilize only published material. When citing information contained in this
document, authors are reminded to cite the original publications, when possible.
iii

CONTENTS
SPECIES STOCK PAGE
Pinnipeds
Steller Sea Lion Western U.S. 1

Steller Sea Lion Eastern U.S. 16

Northern Fur Seal Eastern Pacific 27

Harbor Seal Aleutian Islands, Pribilof Islands, Bristol Bay, N. Kodiak,

S. Kodiak, Prince William Sound, Cook Inlet/Shelikof,

Glacier Bay/Icy Strait, Lynn Canal/Stephens,

Sitka/Chatham, Dixon/Cape Decision, Clarence Strait 37

Spotted Seal Alaska 50

Bearded Seal Alaska 56

Ringed Seal Alaska 63

Ribbon Seal Alaska 72

Cetaceans
Beluga Whale Beaufort Sea 77

Beluga Whale Eastern Chukchi Sea 82

Beluga Whale Eastern Bering Sea 87

Beluga Whale Bristol Bay 92

Beluga Whale Cook Inlet 97

Narwhal Unidentified 104

Killer Whale Eastern North Pacific Alaska Resident 108

Killer Whale Eastern North Pacific Northern Resident 117

Killer Whale Eastern North Pacific Gulf of Alaska, Aleutian Islands,

and Bering Sea Transient 124

Killer Whale AT1 Transient 132

Killer Whale West Coast Transient 138

Pacific White-Sided Dolphin North Pacific 145

Harbor Porpoise Southeast Alaska 149

Harbor Porpoise Gulf of Alaska 155

Harbor Porpoise Bering Sea 161

Dall’s Porpoise Alaska 167

Sperm Whale North Pacific 172

Baird’s Beaked Whale Alaska 177

Cuvier’s Beaked Whale Alaska 181

Stejneger’s Beaked Whale Alaska 185

Humpback Whale Western North Pacific 188

Humpback Whale Central North Pacific 198

Fin Whale Northeast Pacific 209

Minke Whale Alaska 215

North Pacific Right Whale Eastern North Pacific 218

Bowhead Whale Western Arctic 227

Appendices
Appendix 1. Summary of changes for the 2014 stock assessments 240

Appendix 2. Stock summary table 242

Appendix 3. Summary table for Alaska category 2 commercial fisheries 245

Appendix 4. Interaction table for Alaska category 2 commercial fisheries 246

Appendix 5. Interaction table for Alaska category 3 commercial fisheries 248

Appendix 6. Observer coverage in Alaska commercial fisheries, 1990-2009 250

Appendix 7. Self-reported fisheries information 253

Appendix 8. Stock Assessment Reports published by the U.S. Fish and Wildlife Service 257

v

Revised 10/09/2014
STELLER SEA LION (Eumetopias jubatus): Western U.S. Stock
STOCK DEFINITION AND GEOGRAPHIC RANGE
Steller sea lions range along
the North Pacific Rim from northern
Japan to California (Loughlin et al.
1984), with centers of abundance and
distribution in the Gulf of Alaska and
Aleutian Islands (Fig. 1). Large
numbers of individuals disperse widely
outside of the breeding season (late
May-early July), probably to access
seasonally important prey resources.
This results in marked seasonal patterns
of abundance in some parts of the range
and potential for intermixing in foraging
areas of animals that were born in
different areas (Sease and York 2003).
Despite the wide-ranging movements of
juveniles and adult males in particular,
Figure 1. Generalized distribution (crosshatched area) of Steller sea
exchange between rookeries by breeding
lions in the North Pacific and major U.S. haulouts and rookeries (50
adult females and males (other than
CFR 226.202, 27 August 1993), as well as active Asian and
between adjoining rookeries) is low,
Canadian (British Columbia) haulouts and rookeries (points:
although males have a higher tendency
Burkanov and Loughlin 2005; S. Majewski, Fisheries and Oceans
to disperse than females (NMFS 1995,
Canada, personal communication). Black dashed line (144°W)
Trujillo et al. 2004, Hoffman et al.
indicates stock boundary (Loughlin 1997) and solid black line
2006).
delineates U.S. Exclusive Economic Zone.
Loughlin (1997) and Phillips et
al. (2009) considered the following
information when classifying stock structure based on the phylogeographic approach of Dizon et al. (1992): 1)
Distributional data: geographic distribution continuous, yet a high degree of natal site fidelity and low (<10%)
exchange rate of breeding animals between rookeries; 2) Population response data: substantial differences in
population dynamics (York et al. 1996); 3) Phenotypic data: skull morphology (Phillips et al. 2009); and 4)
Genotypic data: substantial differences in mitochondrial DNA (Bickham et al. 1996). Based on this information,
two separate stocks of Steller sea lions were recognized within U.S. waters: an eastern U.S. stock, which includes
animals born east of Cape Suckling, Alaska (144W), and a western U.S. stock, which includes animals born at and
west of Cape Suckling (Loughlin 1997; Fig. 1). However, Jemison et al. (2013) summarized that there is regular
movement of Steller sea lions from the western DPS (males and females equally) and eastern DPS (almost
exclusively males) across the DPS boundary.
Steller sea lions that breed in Asia are considered part of the western stock. Whereas Steller sea lions
seasonally inhabit coastal waters of Japan in the winter, breeding rookeries outside of the U.S. are currently only
located in Russia (Burkanov and Loughlin 2005). Analyses of genetic data differ in their interpretation of separation
between Asian and Alaskan sea lions. Based on analysis of mitochondrial DNA, Baker et al. (2005) found evidence
of a genetic split between the Commander Islands (Russia) and Kamchatka that would include Commander Island
sea lions within the western U.S. stock and animals west of there in an Asian stock. However, Hoffman et al. (2006)
did not support an Asian/western stock split based on their analysis of nuclear microsatellite markers indicating high
rates of male gene flow. Berta and Churchill (2012) concluded that a putative Asian stock is “not substantiated by
microsatellite data since the Asian stock groups with the western stock”. All genetic analyses (Baker et al. 2005;
Harlin-Cognato et al. 2006; Hoffman et al. 2006, 2009; O’Corry-Crowe et al. 2006) confirm a strong separation
between western and eastern stocks, and there may be sufficient morphological differentiation to support elevating
the two recognized stocks to subspecies (Phillips et al. 2009), although a recent review by Berta and Churchill
(2012) characterized that status of these subspecies assignments as “tentative” and requiring further attention before
their status can be determined. Recent work by Phillips et al. (2011) addressed the effect of climate change, in the
form of glacial events, on the evolution of Steller sea lions and reported that the effective population size at the time
of the event determines the impact of change on the population. The results suggested that during historic glacial
periods, dispersal events were correlated with historically low effective population sizes, while range fragmentation
type events were correlated with larger effective population sizes. This work again reinforced the stock delineation
concept by noting that ancient population subdivision likely led to the sequestering of most mtDNA haplotypes as
DPS, or subspecies-specific (Phillips et al. 2011).
In 1998, a single Steller sea lion pup was observed on Graves Rock in northern Southeast Alaska, and by
2013, pup counts had increased to 551 (DeMaster 2014). Mitochondrial and microsatellite analysis of pup tissue
samples collected in 2002 revealed that approximately 70% of the pups had mtDNA haplotypes that were consistent
with those found in the western stock (Gelatt et al. 2007). Similarly, a rookery to the south on the White Sisters
Islands where pups were first noted in 1990 was also sampled in 2002 and approximately 45% of those pups had
western stock haplotypes. Collectively, this information demonstrates that these two most recently established
rookeries in northern southeast Alaska have been partially to predominately established by western stock females.
Movements of animals marked as pups in both stocks support these genetic results (Jemison et al. 2013). Overall,
however, the observations of marked sea lion movements corroborate the extensive genetics research findings for a
strong separation between the two currently recognized stocks. Although recent colonization events in the far
northern part of the eastern DPS indicate movement of western sea lions into this area, the mixed part of the range
remains small (Jemison et al. 2013), and the overall discreteness of the eastern from the western stock remains
distinct. Hybridization among subspecies and species along a contact zone such as now occurs near the stock
boundary is not unexpected as the ability to interbreed is a primitive condition whereas reproductive isolation would
be derived. In fact, as stated by NMFS and FWS in a 1996 response to a previous comment regarding stock
discreteness policy (61 FR 47222), “The Services do not consider it appropriate to require absolute reproductive
isolation as a prerequisite to recognizing a distinct population segment” or stock. The fundamental concept
overlying this distinctiveness is the collection of morphological, ecological and behavioral, and genetic evidence for
stock differences initially described by Bickham et al. (1996) and Loughlin (1997), and supported by Baker et al.
(2005), Harlin-Cognato et al. (2006), Hoffman et al. (2006, 2009), O’Corry-Crowe et al. (2006), and Phillips et al.
(2009, 2011).
POPULATION SIZE
The most recent comprehensive aerial photographic and land-based surveys of western Steller sea lions in
Alaska were conducted in 2008-2013 (Fritz et al. 2013, DeMaster 2014). An estimate of the total population size of
western Steller sea lions in Alaska can be obtained by multiplying the best estimate of total pup production by 4.5
(Calkins and Pitcher 1982). Total pup production in Alaska in 2013 was estimated to be 12,316 (95% credible
interval: 11,741-12,926) using a Bayesian hierarchical model, agTrend (Johnson and Fritz 2014), and 2013 survey
results (DeMaster 2014). When multiplied by 4.5, this yields a total population estimate of 55,422 (95% credible
interval: 52,834-58,167). This is not a minimum abundance estimate since it is an extrapolated total population size
from pup counts based on survival and fecundity estimates for an assumed stable, mid-1970s central Gulf of Alaska
population (Fig. 2; Calkins and Pitcher 1982) and may not be appropriate for use in estimating the abundance of the
Alaskan western stock as a whole given the considerable regional variation in current trends: populations east of
Samalga Pass are generally increasing, while those to the west are decreasing (Fig. 2; Fritz et al. 2013, DeMaster
2014). Vital rates of Steller sea lions in the central Gulf of Alaska may have changed considerably since the mid­
1970s as the population declined through the 1980s and 1990s and has been slowly increasing in the 2000s (York
1994, Holmes and York 2003, Fay and Punt 2006, Pendleton et al. 2006, Winship and Trites 2006, Holmes et al.
2007, DeMaster 2014). For the increasing eastern stock of Steller sea lion, Pitcher et al. (2007) showed that the
multiplier could range between 4.2 and 5.2 depending on the combination of changes to survival and natality.
Methods used to survey Steller sea lions in Russia differ from those used in Alaska, with less use of aerial
photography and more use of skiff surveys and cliff counts for non-pups and ground counts for pups. The most
recent counts of non-pup Steller sea lions in Russia were conducted in 2007-2011, and totaled ~12,700 (V.
Burkanov, NMFS Alaska Fisheries Science Center, NMML, 7600 Sand Point Way NE, Seattle, WA 98115, pers.
comm.). The most recent estimate of pup production in Russia is available from counts conducted in 2011 and
2012, which totaled 6,021 pups and yields a total population abundance estimate of 27,100 Steller sea lions using the
4.5 multiplier.
An estimate of the abundance of the entire (U.S. and Russia) western stock of Steller sea lions (pups and
non-pups) can be made by adding the most recent estimates of U.S. and Russian pup production, and multiplying by
4.5 (12,316 + 6,021 = 18,337 pups × 4.5), which yields 82,516.
2