Policy decisions in fishery management are becoming increasingly
complex and difficult. This is especially true for the salmon fisheries
where policy outcomes affect the productivity of the salmon
resource and the subsequent well-being of commercial fishermen, charter
boat operators, Indian fishermen, and sport anglers. The objective
of this study was to advance methodology from statistical
decision analysis which would assist fishery managers in Oregon who
must make particularly difficult choices with respect to allocation
and production of coho salmon while recognizing uncertainties in the
environment, incomplete state of knowledge, and the conflicting needs
and desires of different interest groups.
The method chosen given multiple objectives and uncertainty is
multiattribute utility analysis. The approach consists, of two main
components: (1) a computer model which simulates the life cycle of
hatchery and stream spawning coho salmon given environmental variation,
different hatchery juvenile release levels and harvest rates;
and (2) an objective function which relates the different outcomes
from alternative release levels and harvest rates to an assessment
of the degree to which individual objectives are met.
The approach was used to evaluate and rank the expected outcomes
from twelve proposed policies under different hypothesized ocean
environments. Analysis of the results suggest that (1) the most
effective policy is achieved with a relatively low harvest rate and
high smolt release level; (2) selection of a particular harvest rate
is the most important decision variable; and (3) a large smolt release
level can be maintained unless such releases adversely decreases the
ocean survival of stream spawning coho.
Because the coho fishery is a mixed stock fishery consisting of
hatchery and wild stocks, the results suggest that too high a harvest
rate will lead to depletion of wild stocks, considered important because
of their potential contribution to production and diverse genetic
traits and characteristics. Conversely, too low a harvest rate
will lead to excessive escapement of coho and thus reduce the total
catch.
As is illustrated, formulating the coho decision problem in a
multiattribute utility analysis framework is useful in two ways.
First, by quantifying the objectives of the decision maker, consistent
results from following alternative policies can be determined.
These results provide a basis for comparison and serve as a guide for
decision making involving uncertainty. Second, the approach is
useful in isolating major objectives and conflicts, value judgments,
trade-offs, and needed empirical evidence. / Graduation date: 1982
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/26730 |
| Date | 11 February 1982 |
| Creators | Walker, Kevin D. |
| Contributors | Rettig, R. Bruce |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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