Population viability of the Snake River chinook salmon (Oncorhynchus tshawytscha). Recovery issues for threatened and endangered Snake River salmon, Technical report 11 of 11.

摘要

A stochastic simulation model of spring chinook population dynamics was parameterized using 36 years of redd count data from five index streams on the middle fork of the Salmon River in Idaho. Two versions of the model, one in which spawning age structure was presumed to follow an evolutionarily stable strategy and another in which spawning age structure was constrained to observed values were examined. The models were then used to generate 1000 statistically representative population projections over the next 100 years to assess risk of extinction and prospects for stock rebuilding. Current levels of production and mortality appear to suffice for maintaining the status quo, virtually assuring persistence over the next 100 years, barring catastophes, but providing no hope for rebuilding. A doubling of the current population level over the next 100 years can be expected to follow an increase in (alpha) (density independent mortality or fry production) of 5 to 25%, but rebuilding to the population levels prevailing in the 1950's will require an increase in (alpha) of at least 37%.