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Stock Dynamics and Adaptive Management of Habitat: An Evaluation Based on Simulations
Author(s) -
Williams John G.
Publication year - 1999
Publication title -
north american journal of fisheries management
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.587
H-Index - 72
eISSN - 1548-8675
pISSN - 0275-5947
DOI - 10.1577/1548-8675(1999)019<0329:sdaamo>2.0.co;2
Subject(s) - oncorhynchus , fish migration , chinook wind , habitat , fishery , stock (firearms) , restoration ecology , population , ecology , adaptive management , geography , environmental science , fish <actinopterygii> , biology , demography , archaeology , sociology
Simulations based on the Ricker and Beverton–Holt stock–recruitment models illustrate the difficulties with developing information about the effectiveness of habitat restoration efforts from the relation between measurements of habitat and populations of anadromous fishes. The relation between the two is confounded by density‐dependent mortality and variable density‐independent mortality and is masked by measurement errors. The simulations are considered in terms of populations of fall‐run (ocean‐type) chinook salmon Oncorhynchus tshawytscha from the Sacramento–San Joaquin river system of central California, where major federal and state efforts are underway to restore anadromous fish populations, as well as brackish and freshwater ecosystems. The simulations show that to implement effective adaptive management of salmon habitat, these efforts must move beyond a trial and error approach in which efforts to restore salmon habitat will be evaluated by population responses. A more promising alternative is evaluating restoration efforts by identifying and testing hypotheses about the mechanisms or processes that relate the restoration actions to populations.