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Suggested Citation:"Appendix C: Glossary." National Research Council. 2003. Decline of the Steller Sea Lion in Alaskan Waters: Untangling Food Webs and Fishing Nets. Washington, DC: The National Academies Press. doi: 10.17226/10576.
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APPENDIX C Glossary


Acceptable biological catch (ABC)

a preliminary description of acceptable harvest (or range of harvests) for a given stock or stock complex. Its derivation focuses on the status and dynamics of the stock, environmental conditions, other ecological factors, and prevailing technological characteristics of the fishery. The fishing mortality rate used to calculate ABC is constrained to be lower than rates associated with overfishing.


Catch per unit effort (CPUE)

an index showing the ratio of a catch of fish, in numbers or in weight, and a standard measure of the fishing effort expended to catch them.


Maximum sustainable yield (MSY)

the largest average catch or yield that can be continuously taken from a stock under existing environmental conditions.

Metapopulation

a set of local populations in some larger area, where migration between patches is possible (Hanski and Simberloff, 1997).


Odobenids

one of the three families of pinnipeds. This family is primarily made up of walruses.

Otariids

one of the three families of pinnipeds. This family is primarily made up of sea lions and fur seals.

Suggested Citation:"Appendix C: Glossary." National Research Council. 2003. Decline of the Steller Sea Lion in Alaskan Waters: Untangling Food Webs and Fishing Nets. Washington, DC: The National Academies Press. doi: 10.17226/10576.
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Phocids

one of the three families of pinnipeds. This family is primarily made up of true seals.


Recruitment overfishing

the rate of fishing above which recruitment to the exploitable stock becomes significantly reduced. This is characterized by a greatly reduced spawning stock, a decreasing proportion of older fish in the catch, and generally very low recruitment year after year.


Spawning stock biomass (SSB)

the total weight of all sexually mature fish in the population. This quantity depends on year-class abundance, the exploitation pattern, the rate of growth, fishing and natural mortality rates, the onset of sexual maturity, and environmental conditions.


Total allowable catch (TAC)

an annually determined catch that is species specific and based on consideration of maximum sustainable yield, equilibrium yield, and optimum yield for the groundfish complex as a whole.

Suggested Citation:"Appendix C: Glossary." National Research Council. 2003. Decline of the Steller Sea Lion in Alaskan Waters: Untangling Food Webs and Fishing Nets. Washington, DC: The National Academies Press. doi: 10.17226/10576.
×
Page 188
Suggested Citation:"Appendix C: Glossary." National Research Council. 2003. Decline of the Steller Sea Lion in Alaskan Waters: Untangling Food Webs and Fishing Nets. Washington, DC: The National Academies Press. doi: 10.17226/10576.
×
Page 189
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For an unknown reason, the Steller sea lion population in Alaska has declined by 80% over the past three decades. In 2001, the National Research Council began a study to assess the many hypotheses proposed to explain the sea lion decline including insufficient food due to fishing or the late 1970s climate/regime shift, a disease epidemic, pollution, illegal shooting, subsistence harvest, and predation by killer whales or sharks. The report's analysis indicates that the population decline cannot be explained only by a decreased availability of food; hence other factors, such as predation and illegal shooting, deserve further study. The report recommends a management strategy that could help determine the impact of fisheries on sea lion survival -- establishing open and closed fishing areas around sea lion rookeries. This strategy would allow researchers to study sea lions in relatively controlled, contrasting environments. Experimental area closures will help fill some short-term data gaps, but long-term monitoring will be required to understand why sea lions are at a fraction of their former abundance.

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