Ecological, Economic, and Social Changes as a Result of Sea Otter Recolonization in Southern Southeast Alaska
Investigators
Ginny EckertFisheries DivisionSchool of Fisheries and Ocean Sciences, University of Alaska Fairbanks
Allison RiceMarine Advisory ProgramUniversity of Alaska Fairbanks
Student
- Zachary Hoyt, PhD program
Synopsis
Please see The Southern Southeast Alaska Sea Otter Project website for additional information.
Sea otter numbers and range have expanded throughout southeastern Alaska, with unquantified environmental and economic impacts to commercial fisheries. This project investigates the impact of sea otter recolonization on the region by estimating the rate at which four commercially important species—geoduck clams, California sea cucumbers, red sea urchins, and Dungeness crab—are being depleted by sea otters. Researchers also will conduct an outreach program in the communities of Ketchikan, Craig, Hydaburg, Kake, and Petersburg to present and obtain information on how the growing sea otter population and resulting changes in the environment are affecting the region socially and economically. Finally, researchers will engage stakeholders in a discussion on ecosystem management and potential solutions for these coastal communities.
Overview
The issue
Sea otter population growth, and predation on commercially important shellfish species, are of increasing concern to commercial fishermen in Southeast Alaska. At a recent Board of Fisheries meeting examining shellfish proposals, seven of sixteen Dungeness crab proposals represented attempts to close specific areas to commercial or sport fishing for shellfish species, as a response to predation by sea otters. The proposals are indicative of the contraction of the total area available to commercial shellfish harvest due to sea otter predation. Finding meaningful solutions to the problems this presents to commercial, sport, and subsistence users is difficult, if not impossible, without a good understanding of the extent and nature of sea otter use of these species. Long-term business planning for commercial and sport shellfish harvesters is more difficult when the future health of the stock is uncertain.
Why is this an Alaska Sea Grant project?
One of Alaska Sea Grant's six key goals outlined in the 2009–2013 Strategic Plan is sustained, well-managed, and healthy marine, coastal, and watershed ecosystems in Alaska. The program pursues this goal through support of research that provides decision-makers with science-based information which can be used to craft well-informed policies governing the use and conservation of Alaska's marine and coastal resources.
How will researchers conduct their study?
An important aspect of the management of commercial species in an ecosystem context involves the understanding of the natural predation of those species. A particularly important facet is the impact of marine mammals on fisheries, because in many cases the fished species are desired as prey by the marine mammals. The ongoing resource conflict between sea otters and commercial, sport, and subsistence harvesters in southern Southeast Alaska has been under way for at least 15 years.
This project will investigate sea otter recolonization in southern Southeast Alaska, and the effect this recolonization is having on the region, by estimating the rate at which four commercially important species—geoduck clams, California sea cucumbers, red sea urchins, and Dungeness crab—are being depleted by this keystone species.
Since 1993, the Alaska Department of Fish and Game (ADFG) has closed 18 dive fisheries in Southeast Alaska due to presumed sea otter predation. Further, the continued compression of the Dungeness fleet away from areas with sea otters is causing socioeconomic changes to the region. The four commercial fisheries in this project have an annual value of approximately $16 million dollars in Southeast Alaska. This project is the first to address the sea otter–fisheries conflict in the region. Researchers have worked and will continue to work with industry groups, government agencies, and individual stakeholders to design and develop this project. As part of this project researchers will conduct an outreach program, traveling to the communities of Ketchikan, Craig, Hydaburg, Kake, and Petersburg to present and obtain information on how this changing environment is affecting the social and economic aspect of the region.
The most recently published data show an annual increase in the sea otter population of 6.6%; however, data collected as part of the ADFG research program suggest the sea otter population is increasing more rapidly in both numbers and distribution. Researchers will conduct population abundance estimates of sea otters on the outside coast of southern Southeast Alaska using an aerial survey method during summer 2010. Subsequent to the population estimate, an extensive sea otter prey study will be conducted through observation techniques using a bioenergetics approach. The design of this prey diet study will use information obtained from the outreach, aerial survey, and ADFG fishery assessments to set up shore-based sampling stations over our proposed study site. The data will then be applied to the sea otter population estimates to complete an estimate of commercially important species being consumed by sea otters in the region. The annual predation by sea otters calculated as part of this project will then be compared to fishery assessment data collected by ADFG, and conclusions drawn on the future sustainability and distribution of these fisheries. This summarized information will then travel back to the five communities in a final outreach effort to engage a discussion on ecosystem management and potential solutions for the coastal communities.
Research collaborators
Alaska Department of Fish and Game
Southeast Alaska Regional Dive Fisheries Association
Petersburg Marine Mammal Center
Petersburg Vessel Owners Association
Alaska Sea Grant Marine Advisory Program in Ketchikan and Petersburg
U.S. Fish and Wildlife Service
U.S. Geological Survey
Icicle Seafoods
Results
Research outcomes
Management of sea otters currently has no mechanism for sustainability in southern Southeast Alaska. Data derived from this study on otter abundance and distribution are critical to future management and policy decisions. This project will provide stakeholders with valuable data to make predictions about potential future earnings in their fisheries or businesses. Information gathered and distributed in this project will also allow stakeholders to lobby for management or legislative changes to address any predicted declines in shellfish populations. The results of this project will be included in a doctoral thesis and subsequently prepared as peer reviewed manuscripts. Finally, the project will increase understanding by shellfish users and the public on the biology of sea otters, crabs, geoduck clams, sea urchins, and sea cucumbers.
