Abundance, distribution, and migratory behavior of coastal cutthroat trout in two lower Columbia River tributaries

Identification Information

Citation

Originator: Hering, D. T. Cornwell and K. Jones

Publish Date: 2009

Online Link: None

BPA Project #:

Contact Information

Agency: Oregon Department of Fish and Wildlife

Name: Cedric Cooney

Job Position: Natural Resources Data and Systems Manager

Telephone: 503-947-6094

E-Mail Address: cedric.x.cooney@odfw.oregon.gov

Description

Abstract: Coastal cutthroat trout (Oncorhynchus clarki clarki) exhibit multiple life history types characterized by diverse migratory strategies, including anadromous, potomodromous, and freshwater resident forms. The factors contributing to life history variation within populations are not well understood, but probably are not strictly genetic (e.g. Johnson et al, in review). Variation in migration tendency within cutthroat populations may result from phenotype plasticity, influenced by density, frequency, or condition dependent processes (Hendry et al. 2004). For example, an individual cutthroat’s choice to migrate at a given time or age may be a response to environmental conditions mediated by a genetically determined reaction norm (Hutchings 2004). This report summarizes a study undertaken to describe the expression of migratory behavior within coastal cutthroat trout populations, the relationship among migratory and non-migratory individuals, and the implications of life history diversity for management of cutthroat trout in tributaries of the lower Columbia River. The relationship between resident and migratory populations (or resident and migratory individuals within populations) is of central importance for management of coastal cutthroat trout. In the lower Columbia River and southwest Washington State a proposed rule to list anadromous cutthroat as threatened under the federal Endangered Species Act (ESA) was withdrawn after the US Fish and Wildlife Service (USFWS) decided during its review process to include resident and anadromous forms in the same Distinct Population Segment (DPS). Debate over proposed ESA listing highlighted a general lack of knowledge about coastal cutthroat trout life history, relationships between resident and migratory forms, and estuarine habitat use in the lower Columbia River. In 2009, the decision not to list the DPS as threatened was remanded to the USFWS on the grounds that the Service had not adequately considered whether marine and estuarine habitats formed a significant portion of the range of the DPS (USFWS 2009). We evaluated the distribution and abundance of coastal cutthroat trout in Big Creek and Bear Creek, two tributaries that join the Columbia River estuary from the south (Oregon) side roughly 30 kilometers from the ocean, and monitored the migratory behavior of cutthroat that emigrated from these streams and entered the Columbia River estuary. Big Creek is an interesting system because a fish weir and diversion dam at an ODFW hatchery, established in 1941 and refurbished in 1957, prevent cutthroat trout from passing upstream, isolating the cutthroat spawning population above the hatchery. Despite this barrier to upstream migration, offspring of resident cutthroat in the upper watershed continue to “smolt” and migrate downstream past the barrier. We were interested in the fate of these fish and their contribution to the adult population. Bear Creek, on the other hand, has always had full access for anadromous cutthroat through much of its drainage. These two systems permit a comparison of life history characteristics, migration, and survival of coastal cutthroat rearing in streams above and below migration barriers, and provide study sites in Oregon to compliment research by USFWS of coastal cutthroat migration behavior in tributaries entering the estuary from the north side of the Columbia River (USFWS 2008; and see Hudson et al. 2008; Johnson 2008; Zydlewski et al. 2008). A major objective of our work in Big Creek and Bear Creek was to increase understanding of coastal cutthroat trout biology and the relationship between resident and migratory cutthroat in lower Columbia tributaries. Additionally, we sought to document habitat use in the Columbia River estuary by migrant cutthroat. Our specific objectives were to: • Estimate abundance of coastal cutthroat trout in Big Creek (above hatchery barrier) and Bear Creek (above and below a large dam) • Quantify the proportions of the cutthroat populations that are migratory, identify which individuals migrate and describe the timing of migration • Describe habitats used by anadromous migrants and characterize migration behavior within the Columbia River estuary • Measure estuarine/marine survival of anadromous individuals and document return to natal streams

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Geographic Extent: Big and Bear Creek

Status: Final

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Format: PDF File

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Is a physical copy maintained for reference at Headquarters? No