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Marine Mammal Protection Act; Stock Assessment Report

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Fish and Wildlife Service, Interior.


Notice of availability of draft revised marine mammal stock assessment report for the northern sea otter stock in Washington State; request for comments.


In accordance with the Marine Mammal Protection Act (MMPA), the Fish and Wildlife Service (Service) has developed a draft revised marine mammal stock assessment report for the northern sea otter (Enhydra lutris kenyoni) stock in Washington State, which is available for public review and comment.


Comments must be received by July 16, 2008.


Copies of the draft revised stock assessment report for the northern sea otter in Washington State are available from the Manager, U.S. Fish and Wildlife Service, Western Washington Fish and Wildlife Office, 510 Desmond Drive, SE., Suite 102, Lacey, WA 98503, (360) 753-9440. It can also be viewed in Adobe Acrobat at​westwafwo.

If you wish to submit comments on the draft revised stock assessment report for the northern sea otter in Washington State, you may do so by any of the following methods:

1. You may mail or hand-deliver (during normal business hours) written comments to the Manager, U.S. Fish and Wildlife Service, Western Washington Fish and Wildlife Office, 510 Desmond Drive, SE., Suite 102, Lacey, WA 98503.

2. You may fax your comments to (360) 753-9405.

3. You may send comments by electronic mail (e-mail) to

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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 Start Printed Page 20932stock 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 report for northern sea otters in Washington State 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 assessment, as appropriate. We will publish a notice of availability and summary of the final stock assessment, 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 Report for the Northern Sea Otter Stock in Washington State

StockNminRmaxFrPBRAnnual estimated average human-caused mortalityStock status
Northern sea otters (Washington State)7900.200.18UnknownNon-Strategic.

List of References

COSEWIC 2007. COSEWIC assessment and update status report on the sea otter Enhydra lutris in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. vii + 36 pp. (​status/​status_​e_​cfm).

DeMaster, D.P., C. Marzin, and R.J. Jameson. 1996. Estimating the historical abundance of sea otters in California. Endangered Species Update 13(12):79-81.

Estes, J. A. 1990. Growth and equilibrium in sea otter populations. J. Anim. Ecol. 59:358-401.

Gearin, P.J., M. E. Gosho, J. Laake, and R. L. Delong. 1996. Acoustic alarm experiments in the northern Washington marine set-net fishery, method to reduce by-catch of harbor porpoise. Rept. Int. Whal. Commn. SC/48/SM10, 13 pp.

Gerber, L.R. and G.R. VanBlaricom. 1999. Potential fishery conflicts involving sea otters (Enhydra lutris [L.] in Washington State waters. Final report to the Marine Mammal Commission, Contract T30917202, October 1999, 69 pp.

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.

Jameson, R. J., K. W. Kenyon, S. Jeffries and G. R. VanBlaricom. 1986. Status of a translocated sea otter and its habitat in Washington. Murrelet 67:84-87.

Jameson, R.J. 1996. Status reports: West Coast translocation projects, Oregon and Washington. The Otter Raft No. 55, Page 8.

Jameson, R.J., and S. Jeffries 1999. Results of the 1999 Survey of the Washington Sea Otter Population. Unpublished Report. 5 pp.

Jameson, R.J. and S. Jeffries. 2006. Results of the 2006 Survey of the Reintroduced Sea Otter Population in Washington State. Unpublished Report. 7 pp.

Laidre, K., R.J. Jameson, S.J. Jeffries, R.C. Hobbs, C.E. Bowlby, and G.R. VanBlaricom. 2002. Estimates of carrying capacity for sea otters in Washington state. Wildl. Soc. Bull. 30(4):1172-1181.

Lance, M.M., S.A. Richardson, and H. Allen. 2004. State of Washington sea otter recovery plan. WDFW, Olympia, WA. 91 pp.

Riedman, M. L., and J. A. Estes. 1990. The sea otter (Enhydra lutris): behavior, ecology, and natural history. U.S. Fish and Wildlife Service, Washington, D.C., Biological Report 90(14). 126 pp.

Scheffer, V.B. 1940. The sea otter on the Washington coast. Pacific Northwest Quarterly, 3:370-388.

Taylor, B.L., M. Scott, J. Heyning, and J. Barlow. 2002. Suggested guidelines for recovery factors for endangered marine mammals. Unpublished report submitted to the Pacific Scientific Review Group. 7 pp.

U.S. Department of Commerce (USDC). National Marine Fisheries Service 2003. Harbor seal (Phoca vitulina richardsi): Washington inland waters stock, stock assessment report. 6 pp.

U.S. Fish and Wildlife Service. 2003. Final revised recovery plan for the southern sea otter (Enhydra lutris nereis). Portland, Oregon. xi + 165 pp.

Watson, J.C. 2000. The effects of sea otters (Enhydra lutris) on abalone (Haliotis spp.) populations. Pages 123-132 In: Workshop on rebuilding abalone stocks in British Columbia. Ed. A. Campbell. Canadian Special Publication of Fisheries and Aquatic Sciences 130 pp.

Wilson, D. E., M. A. Bogan, R. L. Brownell, Jr., A. M. Burdin, and M. K. Maminov. 1991. Geographic variation in sea otters, Enhydra lutris. J. Mammal. 72(1):22-36.

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Dated: April 11, 2008.

Pamela A. Matthes,

Acting Director, Fish and Wildlife Service.

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[FR Doc. E8-8209 Filed 4-16-08; 8:45 am]