The research involved development of two ecological
simulation models to explain the complex dimensionality of
chinook salmon (Oncorhynchus tshawytscha) life history
structure (represented by the age composition of the
spawning stock) and management difficulties entailed in the
complexity.
Since different sizes of chinook salmon are thought to
adapt differently to heterogeneous habitats, age composition
of the spawning stock is determined by characteristics of
the habitats of the substocks. Numerical properties of
substocks result from the incorporation of individual
spawners in different age classes and each substock performs
differently because their age compositions are distinctive.
A stock or population consists of substocks whose age
compositions are concordant with their habitats. The
productive capacity of a population will result from the
incorporation of substocks. If habitat structures of
streams are different, the age and size compositions and
productive capacity of the populations may differ.
Selective harvesting affects spawners in different
ways, so that age compositions must be deformed differently
by fishing pressure. Once the age composition deviates from
the natural age composition, the productivity of the
population will decrease.
Population dynamics are strongly correlated with
substock structure which is determined by habitat structure
in a stream system. Hierarchical population structure make
fisheries management difficult and requires not only
quantitative but also qualitative analysis on the
populations in relation to habitat classification. / Graduation date: 1990
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/38218 |
| Date | 13 March 1990 |
| Creators | Hirai, Takayuki |
| Contributors | Liss, William J. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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