Marine Mammal Protection Act: Stock Assessment Reports,


[Federal Register: February 6, 2008 (Volume 73, Number 25)]


[Page 6994-6996]

From the Federal Register Online via GPO Access []



Fish and Wildlife Service

Marine Mammal Protection Act; Stock Assessment Reports

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Notice of availability of draft revised marine mammal stock assessment reports for three stocks of northern sea otters in Alaska; request for comments.

SUMMARY: In accordance with the Marine Mammal Protection Act (MMPA), the Fish and Wildlife Service (Service) has developed draft revised marine mammal stock assessment reports for the three stocks of northern sea otters (Enhydra lutris kenyoni) in Alaska, which are available for public review and comment.

DATES: Comments must be received by May 6, 2008.

ADDRESSES: Copies of the draft revised stock assessment reports for northern sea otters in Alaska are available from the Marine Mammals Management Office, U.S. Fish and Wildlife Service, 1011 East Tudor Road, Anchorage, AK 99503 (800) 362-5148.

If you wish to submit comments on the draft revised stock assessment reports for northern sea otters in Alaska, you may do so by either of the following methods:

1. You may submit written comments to the Manager, U.S. Fish and Wildlife Service, Marine Mammals Management Office, U.S. Fish and Wildlife Service, 1011 East Tudor Road, Anchorage, AK 99503.

2. You may hand-deliver written comments to our Marine Mammals Management Office at the above address during normal business hours from 8 a.m. to 4:30 p.m. Monday through Friday, or you may fax your comments to 907/786-3816.

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SUPPLEMENTARY INFORMATION: One of the goals of the MMPA is to ensure that stocks of marine mammals occurring in waters under the jurisdiction of the United States do not experience a level of human- caused mortality and serious injury that is likely to cause the stock to be reduced below its optimum sustainable population level (OSP). OSP is defined as ``* * * the number of animals which will result in the maximum productivity of the population or the species, keeping in mind the carrying capacity of the habitat and the health of the ecosystem of which they form a constituent element.''

To help accomplish the goal of maintaining marine mammal stocks at their OSPs, section 117 of the MMPA (16 U.S.C. 1361-1407) requires the Service and the National Marine Fisheries Service (NMFS) to prepare stock assessment reports for each marine mammal stock that occurs in waters under the jurisdiction of the United States. These stock assessments are to be based on the best scientific information available and are, therefore, prepared in consultation with established regional scientific review groups. Each stock assessment must include: (1) A description of the stock and its geographic range; (2) minimum population estimate, maximum net productivity rate, and current population trend; (3) estimate of human-caused mortality and serious injury; (4) commercial fishery interactions; (5) status of the stock; and (6) potential biological removal level (PBR). The PBR is defined as ``* * * the maximum number of animals, not including natural mortalities, that may be removed from a marine mammal stock while allowing that stock to reach or maintain its OSP.'' The PBR is the product of the minimum population estimate of the stock (Nmin), one-half the maximum theoretical or estimated net productivity rate of the stock at a small population size (Rmax); and a recovery factor (Fr) of between 0.1 and 1.0, which is intended to compensate for uncertainty and unknown estimation errors.

Section 117 of the MMPA also requires the Service and the NMFS to review and revise the stock assessment reports: (a) At least annually for stocks that are specified as strategic stocks; (b) at least annually for stocks for which significant new information is available; and (c) at least once every 3 years for all other stocks.

A strategic stock is defined in the MMPA as a marine mammal stock: (A) For which the level of direct human-caused mortality exceeds the potential biological removal level; (B) which, based on the best available scientific information, is declining and is likely to be listed as a threatened species under the Endangered Species Act of 1973, as amended (16 U.S.C. 1531 et seq.), within the foreseeable future; or (C) which is listed as a threatened or endangered species under the Endangered Species Act, or is designated as depleted under the MMPA.

A summary of the draft revised stock assessment reports is presented in Table 1. The table lists the stock=s Nmin, Rmax, Fr, PBR, annual estimated human-caused mortality and serious injury, and the status. After consideration of any public comments received, the Service will revise the stock assessments, as appropriate. We will publish a notice of availability and summary of the final stock assessments, including responses to the comments received.

In accordance with the MMPA, a list of the sources of information or public reports upon which the assessment is based is included in this notice.

Table 1.--Summary of Draft Revised Stock Assessment Reports for Three U.S. Northern Sea Otter Stocks.

Annual 5-year estimated human- Serious caused mortality Stock

Nmin Rmax Fr PBR injury -----------------------

Stock status Fishery/ Other Subsistence

Northern sea otters (Southeast AK)............. 9,136 0.20 1.0




322 Non-strategic Northern sea otters (Southcentral AK).......... 12,774 0.20 1.0 1,277



346 Non-strategic Northern sea otters (southwest AK)............. 38,703 0.20 0.25


0 0.2

91 Strategic

List of References

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496. Dizon, A.E., C. Lockyer, W.F. Perrin, D.P. DeMaster, and J. Sisson. 1992. Rethinking the stock concept: a phylogeographic approach. Conservation Biology 6(1):24-36. Doroff, A.M., J.A. Estes, M.T. Tinker, D.M. Burn, and T.J. Evans. 2003. Sea otter population declines in the Aleutian Archipelago. J. Mammalogy. 84(1):55-64. Doroff, A.M., D.M. Burn, M.T. Tinker, R.A. Stovall, and V.A. Gill. In prep. Sea otter population trends in the Kodiak archipelago: Temporal dynamics at the edge of a large-scale decline in abundance. 32pp. Estes, J.A. 1990. Growth and equilibrium in sea otter populations. J. Anim. Ecol. 59:385-401. Estes, J.A., M.T. Tinker, A.M. Doroff, and D.M. Burn. 2005. Continuing sea otter population declines in the Aleutian archipelago. Marine Mammal Science. 21:169-172. Evans, T.J., D.M. Burn and A.R. DeGange. 1997. Distribution and Relative Abundance of Sea Otters in the Aleutian Archipelago. U.S. Fish & Wildlife Service, Marine Mammals Management Technical Report, MMM 97-5. 29pp. Fadely, B.S., and M. Merklein. 2001. Update of preliminary analysis of marine mammal interactions, entanglements, and mortalities observed during the Cook Inlet salmon drift and set gillnet fisheries, 1999-2000. National Marine Mammal Laboratory, Alaska Fisheries Science Center report. 10pp. Garrott, R.A., L. L. Eberhard, and D.M. Burn. 1993. Mortality of sea otters in Prince William Sound following the Exxon Valdez oil spill. Marine Mammal Science 9:343-359. Garshelis, D.L., and J.A. Garshelis. 1984. Movements and management of sea otters in Alaska. Journal of Wildlife Management 48(3): 665- 678. Garshelis, D.L., A.M. Johnson, and J.A. Garshelis. 1984. Social organization of sea otters in Prince William Sound, Alaska. Canadian Journal of Zoology 62:2648-2658. Garshelis, D.L. 1997. Sea otter mortality estimated from carcasses collected after the Exxon Valdez oil spill. Conservation Biology 11(4): 905-916. Gill, V.A., and D.M. Burn. 2007. Aerial surveys of sea otters in Yakutat Bay, Alaska, 2005. U.S. Fish and Wildlife Service, Marine Mammals Management Office. Technical Report MMM 2007-01. 18pp. Gorbics, C.S., and J.L. Bodkin. 2001. Stock structure of sea otters (Enhydra lutris kenyoni) in Alaska. Marine Mammal Science 17(3):632- 647. Irons, D.B., D.R. Nysewander, and J.L. Trapp. 1988. Prince William Sound sea otter distribution in respect to population growth and habitat type. U.S. Fish and Wildlife Service, Anchorage, Alaska. Jameson, R.J., K.W. Kenyon, A.M. Johnson, and H.M. Wight. 1982. History and status of translocated sea otter populations in North America. Wildl. Soc. Bull. 10:100-107. Johnson, A.M. 1982. Status of Alaska sea otter populations and developing conflicts with fisheries. Pages 293-299 in: Transactions of the 47th North American Wildlife and Natural Resources Conference, Washington DC. Kenyon, K.W. 1969. 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Studies of southeastern Alaska sea otter populations: distribution, abundance, structure, range expansion and potential conflicts with shellfisheries. Anchorage, Alaska. Alaska Department of Fish and Game, Cooperative Agreement 14-16-0009-954 with U.S. Fish and Wildlife Service. 24pp. Riedman, M.L. and J.A. Estes. 1990. The sea otter (Enhydra lutris): behavior, ecology, and natural history. U.S. Fish and Wildlife Service, Biol. Rep. 90(14). 126pp. Simenstad, C.A., J.A. Estes, and K. W. Kenyon. 1978. Aleuts, sea otters, and alternate stable-state communities. Science 200:403-411. 127pp. Siniff, D.B., T.D. Williams, A.M. Johnson, and D.L. Garshelis. 1982. Experiments on the response of sea otters, Enhydra lutris, to oil contamination. Biol. Conserv. 2 OR 23:261-272. Stephensen, S.W., D.B. Irons, S.J. Kendall, B.K. Lance, and L.L. MacDonald. 2001. Marine bird and sea otter population abundance of Prince William Sound, Alaska: trends following the T/V Exxon Valdez oil spill, 1989-2000. 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Dated: January 29, 2008. H. Dale Hall, Director, Fish and Wildlife Service.

[FR Doc. 08-498 Filed 2-5-08; 8:45 am]