Download Beluga, Cook Inlet population - Alaska Center for Conservation

Alaska Species Ranking System Summary Report - Beluga, Cook Inlet population
Beluga, Cook Inlet population
Class: Mammalia
Order: Cetacea
Delphinapterus leucas
Conservation Status
Heritage
G Rank: G4T1
Agency
USFWS/NOAA: Listed Endangered
BLM:
AA:
S Rank: S1
SOA: Species of Greatest Conservation Need
USFS:
IUCN: Critically Endangered
Final Rank
Conservation category: II. Red
II = high status and either high biological vulnerability or high action need
Category
Score
Status:
Range
-20 to 20
Biological:
-50 to 50
22
Action:
-40 to 40
-40
20
Higher numerical scores denote greater concern
Status - variables measure the trend in a taxon’s population status or distribution. Higher status scores denote taxa with
known declining trends. Status scores range from -20 (increasing) to 20 (decreasing).
Score
Population Trend (-10 to 10)
10
50% decline from 1994-1998 (Hobbs et al. 2000). A trend line for the 1998-2008 data estimates a decline of 1.45% per year
(Allen and Angliss 2010b).
Distribution Trend (-10 to 10)
10
Surveys through the 1990s indicated that the summer range was shrinking, with a dramatic decrease in whale sightings in the
central and lower portions of the inlet compared to previous decades (Rugh et al. 2000). 96% to 100% of beluga whales now
gather in shallow areas near river mouths in the upper inlet near Anchorage (Shelden 2011). This change is consistent with
reports of great numbers occurring in Trading Bay until 10-15 years ago (Huntington 2000) and reports of belugas
commonly occurring in Kachemak Bay until about 1996 (Rugh et al. 2000).
Status Total:
Biological - variables measure aspects of a taxon’s distribution, abundance and life history. Higher biological scores suggest
greater vulnerability to extirpation. Biological scores range from -50 (least vulnerable) to 50 (most vulnerable).
Population Size (-10 to 10)
20
Score
10
Annual aerial counts corrected for missed groups : 653, 491, 594, 440, 347, 367, 435, 386, 313, 357, 366, 278, 302, 375 in
the years 1994-2007, respectively (Hobbs et al. in review), 321 in 2009 (Allen and Angliss 2010b), and 340 in 2010 (Shelden
2011).
Range Size (-10 to 10)
8
Restricted to Cook Inlet. In spring and early summer, they concentrate near river mouths and shallow waters in northern Cook
Inlet. In winter, belugas are found in the northern and central portions of the inlet, but belugas are only occasionally seen in
the southern portion of the inlet. The mouths of Beluga and Susitna Rivers, as well as Chickaloon Bay, Knik Arm, and
Turnagain Arm are used as calving areas. Total range is around 19,000 km2, but estuary concentration ~330 km2 calculated
in ARCMAP.
Population Concentration (-10 to 10)
2
Aerial surveys and TEK reports indicate that belugas consistently use limited areas near river mouths and shallow estuaries in
northern Cook Inlet, such as Beluga River, Susitna delta, Little Su River, Knik Arm, Turnagain Arm, and Chickaloon Bay
(Goetz et al. 2007).
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Alaska Species Ranking System Summary Report - Beluga, Cook Inlet population
Reproductive Potential
Age of First Reproduction (-5 to 5)
1
Estimates range from 4-10 for females and 8 to 15 for males
Number of Young (-5 to 5)
5
Single calf every 2-3 years.
Ecological Specialization
Dietary (-5 to 5)
-5
Opportunistic feeders known to prey on a wide variety of animals. More than 100 prey species have been identified in diets,
including octopus, squid, crabs, shrimp, clams, mussels, snails, sandworms, and fish such as capelin, cod, herring, smelt,
flounder, sole, sculpin, lamprey, lingcod and salmon. Eulachon and salmon are important food sources for the Cook Inlet
population.
Habitat (-5 to 5)
1
In summer, largest concentrations are associated with very shallow, low-salinity water at the outflow of major rivers in the
upper part of Cook Inlet, where prey availability is relatively high and predator occurrence low.
Biological Total:
22
Action - variables measure current state of knowledge or extent of conservation efforts directed toward a given taxon. Higher
action scores denote greater information needs due of lack of knowledge or conservation action. Action scores range
from -40 (lower needs) to 40 (greater needs).
Management Needs (-10 to 10)
Score
-10
Designated as depleted by NMFS under the Marine Mammal Protection Act, and listed as endangered under the Endangered
Species Act. In 2011, two areas comprising 7,800 square kilometers were designated as critical habitat in the Cook Inlet
(Federal Register 2011). Subsistence harvest management plan designates annual harvest levels and rules based on not
increasing recovery time by more than 25% with 95% certainty, with harvest limits of only 1-2 strikes per year (Angliss and
Outlaw 2006). No subsistence hunting will occur from 2008-2012 because the most recent 5 year average abundance was
below 350 whales (Shelden 2011).
Monitoring Needs (-10 to 10)
-10
Annual abundance estimates have been calculated since 1993. Aerial surveys are flown in June and cover approximately 30%
of Cook Inlet. Year-round aerial surveys were done in 2001 and 2002. NNML also obtains aerial video of whales in August
to determine age structure and the number of calves (Shelden 2011). Satellite tagging by NMFS of 14 beluga whales 20002003 (NMFS 2004a, Angliss and Outlaw 2005).
Research Needs (-10 to 10)
-10
Key factors well documented. Subsistence harvest key limitation to population growth. Other factors such as disease and
contaminant analysis are currently being studied. Other factors potentially affecting abundance include commercial fishing,
shipping, oil exploration, development, water quality from discharge, stranding due to extreme tidal fluctuations, predation
by killer whales.
Survey Needs (-10 to 10)
-10
Cook Inlet has been surveyed thoroughly each year since 1994 and marine mammal surveys have been conducted in
neighboring Alaska waters sufficiently to provide a fairly accurate documentation of beluga distribution. In addition, belugas
have been tagged and their movements monitored (Rugh et al. 2000; Laidre et al. 2000; Hobbs et al. in review.).
Action Total: -40
Supplemental Information - variables do not receive numerical scores. Instead, they that are used to sort taxa to answer specific
biological or managerial questions.
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Alaska Species Ranking System Summary Report - Beluga, Cook Inlet population
Harvest:
Not substantial
Seasonal Occurrence:
Year-round
Taxonomic Significance:
Population
% Global Range in Alaska:
>10%
% Global Population in Alaska:
>25%
Peripheral:
No
Range Map
References
Allen, B. M. and R. P. Angliss. 2010b. Beluga whale (Delphinapterus leucas). NOAA Marine Mammal Stock Assessment
Report. NOAA-TM-AFSC-223.
Angliss, R. P. and K. L. Lodge. 2003. Beluga Whale (Delphinapteras leucas): Cook Inlet Stock. Alaska Marine Mammal
stock assessment reports (SARs). National Marine Mammal Laboratory. Alaska Fisheries Science Center, Seattle, WA.
Available online at: http:
Angliss, R. P. and K. L. Outlaw, Editors. 2003. Draft Alaska marine mammal stock assessments 2003. National Marine
Mammal Laboratory. Alaska Fisheries Science Center, Seattle, WA. Available online at:
http://www.nmfs.noaa.gov/pr/sars/species.htm#smallwhal
Angliss, R. P. and R. B. Outlaw (eds). 2005. Alaska Marine Mammal stock assessment reports (SARs). National Marine
Mammal Laboratory. Alaska Fisheries Science Center, Seattle, WA. Available online at:
http://www.nmfs.noaa.gov/pr/sars/species.htm#otariids.
Angliss, R. P. and R. B. Outlaw (eds). 2006. Alaska Marine Mammal stock assessment reports (SARs). National Marine
Mammal Laboratory. Alaska Fisheries Science Center, Seattle, WA. Available online at:
http://www.nmfs.noaa.gov/pr/sars/species.htm#otariids.
Federal Register. April 11, 2011. Endangered and threatened species: designation of critical habitat for cook inlet beluga
whale. Vol. 76, No. 69: 20180-20214.
Goetz, K. T., D. J. Rugh, A. J. Read, and R. C. Hobbs. 2007. Habitat use in a marine ecosystem: beluga whales
Delphinapterus leucas in Cook Inlet, Alaska. Marine Ecology Progress Series. 330:247-256.
Hobbs, R. C., D. J. Rugh, and D. P. Demaster. 2000. Abundance of belugas, Delphinapterus leucas, in Cook Inlet,
Alaska, 1994-2000. Marine Fisheries Review 62(3):37-45.
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Alaska Species Ranking System Summary Report - Beluga, Cook Inlet population
Hobbs, R. C., K. E. W. Shelden, D. J. Rugh, and S. A. Norman. In review. Draft 2008 status review and extinction
assessment of Cook Inlet belugas (Delphinapterus leucas). AFSC Processed Report.
Huntington, H. P. 2000. Traditional knowledge of the ecology of belugas, Delphinapterus leucas, in Cook Inlet, Alaska.
Marine Fisheries Review 62:134-140.
Laidre, K. L., K. E. W. Shelden, D. J. Rugh, and B. A. Mahoney. 2000. Beluga, Delphiapterus leucas, distribution and
survey effort in the Gulf of Alaska. Marine Fisheries Review 62: 27-36.
Moore, S. E., K. E. W. Shelden, L. K. Litzky, B. A. Mahoney, and D. J. Rugh. 2000b. Beluga, Delphinapterus leucas,
habitat associations in Cook Inlet, Alaska. Marine Fisheries Review 62:60-80.
NatureServe. 2007b. NatureServe Explorer: An online encyclopedia of life [web application]. Version 6.2. NatureServe,
Arlington, Virginia. Available http://www.natureserve.org/explorer.
National Marine Fisheries Service (NMFS). 2004a. National Species of concern list; establishment, additions to list, and
identification factors; candidate species list revised. National Oceanic and Atmospheric Administration. Notices. Federal
Register: Ap
Nowak, R. M. 1991. Walker's mammals of the world. Fifth edition. Vols. I and II. Johns Hopkins Univ. Press, Baltimore.
1629 pp.
O’Corry-Crowe, G. M., R. S. Suydam, A. Rosenberg, K. J. Frost, and A. E. Dizon. 1997. Phylogeography, population
structure and dispersal patterns of the beluga whale Delphinapterus leucas in the western Nearctic revealed by
mitochondrial DNA. Mol. Ecol
Payne, S. A., B. A. Johnson, and R. S. Otto. 1999. Proximate composition of some north-eastern Pacific forage fish
species. Fisheries Oceanography 8:159-177.
Rugh, J. R., K. E. W. Shelden, and B. A. Mahoney. 2000. Distribution of belugas, Delphinapterus leucas, in Cook Inlet,
Alaska, during June/July, 1993-2000. Marine Fisheries Review 62:6-21.
Shelden, K. 2011. The endangered beluga whales of Cook Inlet, Alaska. AFSC Quarterly Report Feature (JanuaryFebruary-March 2011) 7 p.
Version date: 12/21/2012
Report authors: K. Walton, T. Gotthardt, and T. Fields
Alaska Natural Heritage Program
University of Alaska Anchorage
Anchorage, AK 99501
For details on the development of the ASRS and criteria, please see: Gotthardt, T. A., K. M. Walton, and T. L. Fields. 2012.
Setting Conservation Priorities for Alaska's Wildlife Action Plan. Alaska Natural Heritage Program, University of Alaska
Anchorage, AK.
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