Recipient Organization
UNIV OF IDAHO
875 PERIMETER DRIVE
MOSCOW,ID 83844-9803
Performing Department
Fish and Wildlife Sciences
Non Technical Summary
The behavior of individual animals affects survival, growth, and subsequent reproductive potential. Variation in individual behavior and variation in habitat quality interact, creating differences in reproductive potential between animals of the same species. Indeed, differences between individuals within a species is a pre-requisite for evolution by natural selection. This study will quantitatively identify patterns in size and age-at-maturity of individuals within a species and relate it to habitat variation, population productivity, and the evolution of life-history strategies.Chinook salmon and steelhead migrate down river as juveniles, where they are intercepted at Lower Granite Dam. The size and stock identification of these individuals is recorded. As adults, these fish pass Lower Granite dam again during the upstream "run" to spawning grounds, where they are sampled for size, age, and stock identification. The resulting data has not been exhaustively analyzed to identify effects of freshwater and marine habitat conditions that potentially drive variation in growth and survival.Chinook salmon and steelhead in the Snake River basin are listed as threatened under the Endangered Species Act. Large-scale hatchery programs are managed to provide harvest opportunity while recovering natural-origin stocks. The ability to predict adult size and age will help managers structure fisheries and hatchery programs and manage habitats. For example, younger/smaller females will carry fewer eggs to the spawning grounds, thereby reducing recruits per spawners. The ability to predict loss of productivity across space and time would enable prioritization of recovery efforts.Unveiling patterns in life-history strategies will inform the construction and parameterization of a mechanistic model that optimizes trade-offs. This mechanistic model of optimal life-history strategies is an aspirational future product.
Animal Health Component
70%
Research Effort Categories
Basic
30%
Applied
70%
Developmental
(N/A)
Goals / Objectives
The major goals and objectives of this project are:Contribute to the understanding of steelhead and/or Chinook salmon life history strategies through discovery of patterns in size and age of both juvenile and adult fish that pass Lower Granite Dam.Inform future research by establishing preliminary assessments of existing data.Provide research and consulting experience to a master's degree student in the Department of Mathematics and Statistical Science at the University of Idaho.Specific questions include:What drives variation in size and age of adult salmonids at Lower Granite Dam?Can adult size/age be predicted by juvenile size/age?Can adult size/age be predicted by ocean or freshwater conditions?Are there consistent differences between freshwater age composition of returning adults compared to smolts that may indicate size-selective mortality?Are there stock-specific difference in size/age at the juvenile and adult stages?Geographic stocks (populations).Hatchery vs. wild origin stocks.What are the ecological mechanisms and life-history strategies driving size and age?Can egg count and egg mass from hatchery-origin fish of different size/age be combined with mortality rates to derive an optimality strategy that mimics empirical patterns?
Project Methods
This project will use existing data collected and managed by the Idaho Department of Fish and Game. The data are ages, sizes, and stock/population of juvenile and adult salmonids. Modeling of these data will be performed with R. Specific analytical methods include:Proportional odds logistic regression or similar for discrete ages.Nonlinear models of growth (von Bertalanffy models).Hierarchical models or mixed-effects models for spatially and temporally aggregated fish.Calculus, algebra, or stochastic dynamic programing to model and optimize life-history strategies.