[Federal Register Volume 86, Number 119 (Thursday, June 24, 2021)]
[Notices]
[Pages 33334-33337]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2021-13209]


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DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

[FWS-R8-ES-2021-N008; FF08EVEN00-FXES111608MSSO0]


Marine Mammal Protection Act; Stock Assessment Report for the 
Southern Sea Otter in California

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Notice of availability of final revised stock assessment report 
for the southern sea otter in California; response to comments.

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SUMMARY: In accordance with the Marine Mammal Protection Act of 1972, 
as amended (MMPA), and its implementing regulations, we, the U.S. Fish 
and Wildlife Service (Service), announce that we have revised our stock 
assessment report (SAR) for the southern sea otter stock in the State 
of California, including incorporation of public comments. We now make 
our final revised SAR available to the public.

ADDRESSES: Document Availability: You may obtain a copy of the SAR from 
our website at https://www.fws.gov/ventura/endangered/species/info/sso.html. Alternatively, you may contact the Ventura Fish and Wildlife 
Office, U.S. Fish and Wildlife Service, 2493 Portola Road, Suite B, 
Ventura, CA 93003; telephone: 805-644-1766.

FOR FURTHER INFORMATION CONTACT: For information on the methods, data, 
and results of the stock assessment, contact Lilian Carswell by 
telephone (805-677-3325) or by email ([email protected]). Persons 
who use a telecommunications device for the deaf (TDD) may call the 
Federal Relay Service at 800-877-8339.

SUPPLEMENTARY INFORMATION: We are announcing the availability of the 
final revised SAR for the southern sea otter (Enhydra lutris nereis) 
stock in the State of California.

Background

    Under the MMPA (16 U.S.C. 1361 et seq.) and its implementing 
regulations in the Code of Federal Regulations (CFR) at 50 CFR part 18, 
we regulate the taking; import; and, under certain conditions, 
possession; transportation; purchasing; selling; and offering for sale, 
purchase, or export, of marine mammals. One of the goals of the MMPA is 
to ensure that stocks of marine mammals occurring in waters under U.S. 
jurisdiction 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 (OSP) level. OSP is defined under 
the MMPA 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'' (16 U.S.C. 1362(9)).
    To help accomplish the goal of maintaining marine mammal stocks at 
their OSPs, section 117 of the MMPA requires the Service and the 
National Marine Fisheries Service (NMFS) to prepare a SAR for each 
marine mammal stock that occurs in waters under U.S. jurisdiction. Each 
SAR must include:
    1. A description of the stock and its geographic range;
    2. A minimum population estimate, current and maximum net 
productivity rate, and current population trend;
    3. An estimate of annual human-caused mortality and serious injury 
by source and, for a strategic stock, other factors that may be causing 
a decline or impeding recovery of the stock;
    4. A description of commercial fishery interactions;
    5. A categorization of the status of the stock; and
    6. An estimate of the potential biological removal (PBR) level.
    The MMPA defines the PBR 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]'' (16 
U.S.C. 1362(20)). 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. This can be written as:

PBR = (Nmin)(\1/2\ of the Rmax)(Fr)

    Section 117(c)(1) of the MMPA requires the Service and NMFS to 
review the SARs (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. If our review of the status of a stock 
indicates that it has changed or may be more accurately determined, 
then the SAR must be revised accordingly. (16 U.S.C. 1386(c)(2)).
    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 
[PBR] 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.) [the ``ESA''], within the foreseeable future; or 
(C) which is listed as a threatened species or endangered species under 
the [ESA], or is designated as depleted under [the MMPA].'' (16 U.S.C. 
1362(19)).

Stock Assessment Report History for the Southern Sea Otter in 
California

    The southern sea otter SAR was last revised in 2017 (82 FR 40793, 
August 28, 2017). Because the southern sea otter qualifies as a 
strategic stock due to its listing as a threatened species under the 
ESA, the Service reviewed the stock assessment in 2018. The review 
concluded that the status had not changed, nor could it be more 
accurately determined. However, upon review in 2019, the Service 
determined that revision was warranted because its status could be more 
accurately determined. Before releasing our draft SAR for public review 
and comment, we submitted it for technical review internally and for 
scientific review by the Pacific Regional Scientific Review Group, 
which was established under the MMPA (16 U.S.C. 1386(d)). In a January 
27, 2020, Federal Register notice (85 FR 4696), we made our draft SAR 
available for the MMPA-required 90-day public review and comment 
period. Following the close of the comment period, we revised the SAR 
based on public comments we received (see Response to Public Comments) 
and prepared the final revised SAR. Between publication of the draft 
and final revised SARs, we have not revised the status of the stock 
itself (the southern sea otter continues to retain its status as a 
strategic stock). However, we have updated the SAR to include the most 
recent information available.

[[Page 33335]]

Summary of Final Revised Stock Assessment Report for the Southern Sea 
Otter in California

    The following table summarizes some of the information contained in 
the final revised SAR for southern sea otters in California, which 
includes the stock's Nmin, Rmax, Fr, 
PBR, annual estimated human-caused mortality and serious injury, and 
status:

             Summary: Draft Revised Stock Assessment Report for the Southern Sea Otter in California
----------------------------------------------------------------------------------------------------------------
                                                                       Annual estimated human-
    Southern Sea Otter Stock       Nmin      Rmax       Fr      PBR     caused mortality and      Stock status
                                                                           serious injury
----------------------------------------------------------------------------------------------------------------
Mainland.......................     2,863     0.076      0.1    10.88  Figures by specific     Strategic.
                                                                        source, where known,
                                                                        are provided in the
                                                                        SAR.
San Nicolas Island.............        99     0.192      0.1     0.95
Summary........................     2,962  ........  .......       12
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Response to Public Comments

    We received comments on the draft SAR from the Marine Mammal 
Commission (Commission), the California Department of Fish and 
Wildlife, and a consortium of environmental groups consisting of 
Defenders of Wildlife, Friends of the Sea Otter, the Humane Society of 
the United States, Humane Society Legislative Fund, Earthjustice, 
Center for Biological Diversity, Ocean Preservation Society, Animal 
Welfare Institute, Earth Island Institute, and Earth Law Center. We 
present substantive issues raised in those comments that are pertinent 
to the SAR, edited for brevity, along with our responses below.
    Comment 1: The Commission recommends that the Service review and 
revise the ``Current and Maximum Net Productivity Rates'' section of 
the SAR and provide a rationale for using an Rmax that is 
consistent with the numbers used in the calculation of PBR. Further, 
the Commission recommends that the Service consider the theory behind 
use of Rmax in the PBR calculation and whether 0.13 (or the 
default value of 0.12 for sea otters) is appropriate for a single 
range-wide calculation of PBR.
    Response: We have revised the ``Current and Maximum Net 
Productivity Rates'' section of the SAR to clarify our reasons for 
using particular Rmax values. We have considered the theory 
behind the use of Rmax in the PBR calculation and added a 
brief discussion of the relevance of the PBR calculation to the 
southern sea otter stock. We have not adopted a single range-wide value 
of Rmax for the reasons described in the SAR. However, we 
will present the issue for further consideration by the Pacific 
Scientific Review Group upon our next revision of the SAR.
    Comment 2: The Commission recommends that, at a minimum, the 
Service correct the mainland PBR estimate in the SAR using the mainland 
minimum population estimate. Further, the Commission recommends that 
the Service follow the guidance provided in the Guidelines for 
Assessing Marine Mammal Stocks (NMFS 2016) for rounding the PBR 
estimate and report the PBR to one decimal place.
    Response: We have corrected the mainland PBR estimate and have 
followed the rounding guidance provided in NMFS (2016).
    Comment 3: The Commission recommends that the Service make its 
stock assessment reviews available yearly to the appropriate Scientific 
Review Group (SRG) and the Marine Mammal Commission from this point 
forward.
    Response: We typically provide a presentation to the Pacific SRG on 
the status of the southern sea otter. We will continue to make such 
presentations and explain our stock assessment review process to the 
Pacific SRG and Commission.
    Comment 4: Per the Federal Register notice, since the southern sea 
otter stock is considered strategic, the Service is to evaluate the 
stock annually and develop the SAR based on the best scientific 
information available. This draft SAR was presented for public review 
in January 2020 and does not include evaluation of 2019 data readily 
available on population abundance and distribution.
    Response: We review the SAR, based on the best scientific 
information available, annually to determine whether the status of the 
stock has changed or can be more accurately determined. If such 
findings are made, we revise the SAR. Delays in publication of the 
draft SAR in the Federal Register resulted in the notice of 
availability being published after additional census data had been 
reported. We have updated the SAR with the latest available 
information.
    Comment 5: Adult females with pups do utilize open-water, soft-
bottom habitats. Decades ago, it was rare for this demographic to be 
observed in these habitats. We know pups are challenging to spot during 
aerial surveys and are often missed and therefore not well documented 
in the standard survey method for these habitats. More recent ground-
based survey work and incidental boat-based observations have confirmed 
the presences of mom-and-pup pairs in these open-water habitats.
    Response: We have eliminated excessive detail on habitat use.
    Comment 6: Although the pattern of migration to the range 
peripheries was well documented in the past, it has not been observed 
in over a decade.
    Response: We have eliminated outdated data on habitat use.
    Comment 7: A line should be added to Figure 2 to denote the current 
targeted recovery goal.
    Response: We have not added a line representing the threshold for 
delisting consideration for two reasons. First, we do not wish to 
detract from the purpose of this report under the MMPA, which is 
primarily to assess the progress of the stock toward its OSP level and 
toward a zero-mortality goal for commercial fisheries interactions, not 
to evaluate progress toward recovery goals under the ESA. Second, as we 
explain in text that has been added to the Status of Stock section, the 
threshold for delisting consideration was based on assumptions 
regarding the relationship between effective population size and actual 
population size that are now known to be inaccurate.
    Comment 8: If the report is not updated to reflect 2019 data, we 
suggest that references in the report to ``the past 5 years'' identify 
the specific 5-year period under consideration.
    Response: We have updated the SAR to include the most recent 
available information and have identified the 5-year period under 
discussion.
    Comment 9: The paradigm shift in understanding the reason for slow 
population growth rates in California

[[Page 33336]]

was 6-7 years ago and is not a recent development. The previous 
speculation regarding the reasons for slow growth focused on the 
difference in survival, not reproduction.
    Response: We have revised the discussion of the effects of habitat 
configuration on growth rates.
    Comment 10: There is no explanation why 13 percent was selected as 
Rmax for the San Nicolas Island subpopulation.
    Response: We have updated Rmax for the mainland and 
island subpopulations and added citations to identify the source of 
these numbers.
    Comment 11: The Federal Register notice provides an explanation of 
the intent and scale of the recovery factor. We suggest this 
explanation be included in the report with some explanation of how 0.1 
was selected.
    Response: We believe the SAR adequately explains how a recovery 
factor of 0.1 was selected because it cites Taylor et al. (2003) and 
lists the factors from that discussion that apply to the southern sea 
otter stock. We have not added further explanation.
    Comment 12: There is no evidence the California yellowtail, 
barracuda, and white seabass or California thresher shark/swordfish 
drift gillnet fisheries have sea otter incidental take because it is 
unlikely there is any overlap of these fisheries and sea otter habitat. 
We suggest these be deleted.
    Response: We have removed these drift gillnet fisheries due to a 
lack of habitat overlap.
    Comment 13: We suggest the squid purse-seine fishery be presented 
as a potential risk.
    Response: We have added the California squid purse seine fishery to 
the SAR based on analogy with the California purse seine fishery for 
northern anchovy and Pacific sardine.
    Comment 14: Mortality of sea otters in traps set for crabs, 
lobsters, and finfish is likely under-reported due to the challenges of 
identifying drowning as a cause of mortality in marine mammals.
    Response: We have added this information.
    Comment 15: If possible, the hook-and-line fishers should be 
separated from this discussion of trap fishers. The ``stick gear'' used 
by some hook-and-line commercial fishers likely presents a different 
risk (entanglement).
    Response: These fisheries are grouped together in one category in 
the List of Fisheries, and separate data for the different fishery 
components are not available.
    Comment 16: How has ``unknown hook and line'' been confirmed as 
commercial versus recreational fishing activity such that it is 
included in Table 1?
    Response: Because it is often not possible to make a definitive 
determination whether entanglements are due to commercial or 
recreational gear, we have included here all known strandings caused by 
entanglement in unidentifiable gear. As a result, mortality in 
commercial fishing gear may be overestimated for these categories. We 
have added a note to this effect to Table 1.
    Comment 17: Some shootings are related to fishery interactions, and 
this cause of death is likely under-reported due to the lack of 
systematic radiographs of all carcasses.
    Response: We have added language to this effect to the SAR.
    Comment 18: The SAR does not include mention of Gagne et al. 
(2018), who concluded that the suppositions underlying the effective 
population size and the delisting threshold in the Final Revised 
Recovery Plan for the Southern Sea Otter (2003) were flawed.
    Response: We have added a reference to Gagne et al. (2018) to the 
SAR. However, we note that the species status assessment process we are 
undertaking under the ESA is distinct from our obligations under the 
MMPA.

Additional References Cited

Gagne, R.B., M.T. Tinker, K.D. Gustafson, K. Ralls, S. Larson, L.M. 
Tarjan, M.A. Miller, and H.B. Ernest. 2018. Measures of effective 
population size in sea otters reveal special considerations for 
wide-ranging species. Evolutionary Applications 11:1779-1790.
Gobler, C.J., O.M. Doherty, T.K. Hattenrath-Lehmann, A.W. Griffith, 
Y. Kang, and R.W. Litaker. 2017. Ocean warming since 1982 has 
expanded the niche of toxic algal blooms in the North Atlantic and 
North Pacific oceans. Proceedings of the National Academy of 
Sciences of the United States of America 114:4975-4980.
Harvell, C.D., D. Montecino-Latorre, J.M. Caldwell, J.M. Burt, K. 
Bosley, A. Keller, S.F. Heron, A.K. Salomon, L. Lee, O. Pontier, C. 
Pattengill-Semmens, and J.K. Gaydos. 2019. Disease epidemic and a 
marine heat wave are associated with the continental-scale collapse 
of a pivotal predator (Pycnopodia helianthoides). Science Advances 
5, eaau7042. https://doi.org/10.1126/sciadv.aau7042.
Hatfield, B.B., J.L. Yee, M.C. Kenner, and J.A. Tomoleoni. 2019. 
California sea otter (Enhydra lutris nereis) census results, spring 
2019. U.S. Geological Survey Data Series 1118, Reston, Virginia, 
USA. https://doi.org/10.3133/ds1118.
Jeffries, S., D. Lynch, J. Waddell, S. Ament, and C. Pasi. 2019. 
Results of the 2019 survey of the reintroduced sea otter population 
in Washington State. Washington Department of Fish and Wildlife, 
Lakewood, Washington, USA.
Larson, S., R. Jameson, M. Etnier, T. Jones, R. Hall. 2012. Genetic 
diversity and population parameters of sea otters, Enhydra lutris, 
before fur trade extirpation from 1741-1911. PLoS ONE 7, e32205. 
https://doi.org/10.1371/journal.pone.0032205.
Marshall, K.N., I.C. Kaplan, E.E. Hodgson, A. Hermann, D.S. Busch, 
P. McElhany, T.E. Essington, C.J. Harvey, and E.A. Fulton. 2017. 
Risks of ocean acidification in the California Current food web and 
fisheries: ecosystem model projections. Global Change Biology 
23:1525-1539.
Miller, M.A., M.E. Moriarty, L.A. Henkel, M.T. Tinker, T.L. Burgess, 
F.I. Batac, E. Dodd, C. Young, M.D. Harris, D.A. Jessup, J. Ames, 
P.A. Conrad, A.E. Packham, and C.K. Johnson. 2020. Predators, 
disease, and environmental change in the nearshore ecosystem: 
mortality in southern sea otters (Enhydra lutris nereis) from 1998-
2012. Frontiers in Marine Science. https://doi.org/10.3389/fmars.2020.00582.
Moriarty, M.E., M.T. Tinker, M.A. Miller, J.A. Tomoleoni, M.M. 
Staedler, J.A. Fujii, F.I. Batac, E.M. Dodd, R.M. Kudela, V. 
Zubkousky-White, and C.K. Johnson. 2021. Exposure to domoic acid is 
an ecological driver of cardiac disease in southern sea otters. 
Harmful Algae 101. https://doi.org/10.1016/j.hal.2020.101973.
Moxley, J.H., T.E. Nicholson, K.S. Van Houtan, S.J. Jorgensen. 2019. 
Non-trophic impacts from white sharks complicate population recovery 
for sea otters. Ecology and Evolution 9:6378-6388.
National Marine Fisheries Service. 2016. Guidelines for Preparing 
Stock Assessment Reports Pursuant to Section 117 of the Marine 
Mammal Protection Act. National Marine Fisheries Service Instruction 
02-204-01. http://www.nmfs.noaa.gov/op/pds/index.html.
Nichol, L.M., T. Doniol-Valcroze, J.C. Watson, and E.U. Foster. 
2020. Trends in growth of the sea otter (Enhydra lutris) population 
in British Columbia 1977 to 2017. Research Document 2020/039. 
Fisheries and Oceans Canada, Ottawa, Ontario, Canada. http://publications.gc.ca/site/archivee-archived.html?url=http://publications.gc.ca/collections/collection_2020/mpo-dfo/fs70-6/Fs70-6-2020-036-eng.pdf.
Nicholson, T.E., K.A. Mayer, M.M. Staedler, J.A. Fujii, M.J. Murray, 
A.B. Johnson, M.T. Tinker, and K.S. VanHoutan. 2018. Gaps in kelp 
cover may threaten the recovery of California sea otters. Ecography 
41:1751-1762.
Tinker, M.T., S.M. Espinosa, M.M. Staedler, J.A. Tomoleoni, J. 
Fujii, R. Eby, R. Scoles, M.C. Kenner, B. Hatfield, C. Fuentes, J.K. 
Lindsay, T. Nicholson, M. Murray, M. Young, K. Mayer, E. Dodd, S. 
Fork, and K. Wasson. 2018. The population status and ecology of sea 
otters in Elkhorn Slough, California: final report for California 
Coastal Conservancy and U.S. Fish and Wildlife Service. U. S. 
Geological Survey, Santa Cruz,

[[Page 33337]]

California, USA.
Tinker, M.T., V.A. Gill, G.G. Esslinger, J. Bodkin, M. Monk, M. 
Mangel, D.H. Monson, W.E. Raymond, and M.L. Kissling. 2019a. Trends 
and carrying capacity of sea otters in Southeast Alaska. Journal of 
Wildlife Management 83:1-17.
Tinker, M.T., J.A. Tomoleoni, B.P. Weitzman, M. Staedler, D. Jessup, 
M.J. Murray, M. Miller, T. Burgess, L. Bowen, A.K. Miles, N. 
Thometz, L. Tarjan, E. Golson, F. Batac, E. Dodd, E. Berberich, J. 
Kunz, G. Bentall, J. Fujii, T. Nicholson, S. Newsome, A. Melli, N. 
LaRoche, H. MacCormick, A. Johnson, L. Henkel, C. Kreuder-Johnson, 
and P. Conrad. 2019b. Southern sea otter (Enhydra lutris nereis) 
population biology at Big Sur and Monterey, California; 
investigating the consequences of resource abundance and 
anthropogenic stressors for sea otter recovery. U.S. Geological 
Survey Open-File Report 2019-1022. U.S. Geological Survey, Reston, 
Virginia, USA.
Tinker, M.T., J.L. Yee, K.L. Laidre, B.B. Hatfield, M.D. Harris, 
J.A. Tomoleoni, T.W. Bell, E. Saarman, L.P. Carswell, A.K. Miles. 
2021. Habitat features predict carrying capacity of a recovering 
marine carnivore. Journal of Wildlife Management 85:303-323. https://doi.org/10.1002/jwmg.21985.
Wellman, H.P. 2018. Applied zooarchaeology and Oregon Coast sea 
otters (Enhydra lutris). Marine Mammal Science 34:806-822.
Wellman, H.P., R.M. Austin, N.D. Dagtas, M.L. Moss, T.C. Rick, and 
C.A. Hofman. 2020. Archaeological mitogenomes illuminate the 
historical ecology of sea otters (Enhydra lutris) and the viability 
of reintroduction. Proceedings of the Royal Society B: Biological 
Sciences 287, 20202343. https://doi.org/10.1098/rspb.2020.2343.

Authority

    The authority for this action is the Marine Mammal Protection Act 
of 1972, as amended (16 U.S.C. 1361 et seq.).

Signing Authority

    The Director, U.S. Fish and Wildlife Service, approved this 
document and authorized the undersigned to sign and submit the document 
to the Office of the Federal Register for publication electronically as 
an official document of the U.S. Fish and Wildlife Service. Martha 
Williams, Principal Deputy Director Exercising the Delegated Authority 
of the Director, U.S. Fish and Wildlife Service, approved this document 
on June 17, 2021, for publication.

Krista Bibb,
Acting Regulations and Policy Chief, Division of Policy, Economics, 
Risk Management, and Analytics, Joint Administrative Operations, U.S. 
Fish and Wildlife Service.
[FR Doc. 2021-13209 Filed 6-23-21; 8:45 am]
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