Abundance, Life History, and Distribution of Bull Trout in the Hood River Basin: A Summary of Findings from 2006 to 2009 Information Reports 2010-01

Identification Information

Citation

Originator: Starcevich, S.J and S.E. Jacobs

Publish Date: April 2010

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: Bull trout have been adversely affected by many land, water, and fisheries management activities throughout the range of the species. Degraded and fragmented habitat and negative interactions with nonnative fishes have led to a decline in bull trout distribution and abundance, several local extirpations, and a federal listing in 1998 as a threatened species under the Endangered Species Act (USFWS 2002). Distribution and abundance of bull trout also have declined in Oregon, and most management units in the state are considered to be threatened by conservation risks (ODFW 2005). One of these at-risk management units exists in the Hood River basin (ODFW 2005). Bull trout in Hood River basin currently are thought to exist as two independent reproductive units (USFWS 2002), known as local populations (Rieman and McIntyre 1995). The Clear Branch local population was isolated from the rest of the basin by the construction of Clear Branch Dam in 1968. This dam provides limited downstream fish passage during periods of spill and no voluntary upstream passage. Bull trout in this population inhabit Laurance Lake reservoir and the tributaries Pinnacle Creek and upper Clear Branch, which flow into the reservoir. The Hood River local population is distributed in the mainstem Hood River, Middle Fork Hood River (Middle Fork), and a few Middle Fork tributaries. Fluvial migrants from Hood River basin also forage and winter in the Columbia River (Pribyl et al. 1996, Buchanan et al. 1997). Bull trout have been observed in the East and West Fork basins of the Hood River, but these sightings have been rare. Presently, there is little evidence to suggest local populations exist in these tributary basins (USFWS 2002, Reagan and Olsen 2008). The status of both local populations is extremely precarious. Threats that put the Clear Branch population at risk of extirpation include low abundance, negative interactions with illegally introduced smallmouth bass, isolation from upstream migration and immigration, and diminished spawning and rearing habitat (USFW 1998). The Hood River population also appears to be small and is affected by passage barriers, unscreened irrigation diversions, impaired water quality, and periodic debris flows during glacial outbursts (USFWS 1998). As mandated by their federally designated threatened status, recovery plans were drafted by the US Fish and Wildlife Service (USFWS) for each distinct population segment, including for Hood River bull trout in 2002. This draft plan listed four goals for recovery in this basin: 1) establish at least one more local population in addition to the two existing populations, 2) increase the estimated adult population in the basin to at least 500 individuals, 3) achieve a stable or increasing trend at the population recovery level for at least two generations (=10 years), and 4) improve habitat connectivity by addressing problems with passage and screening at diversions and seasonal water quality barriers (USFWS 2002). The recovery plan also sets out research and monitoring needs critical to the recovery of these populations. Needed are accurate adult abundance estimates; a standardized monitoring program; more life history information for each local population, including how Hood River bull trout use of the Columbia River and the effects of potential passage obstructions on movement; and more information on the threat posed to the Clear Branch population by the illegal introduction of smallmouth bass in Lake Laurance reservoir. The Oregon Department of Fish and Wildlife (ODFW), with the help of the USDA Forest Service (USFS), initiated a four-year study in 2006 seeking to address these needs by synthesizing available data and conducting further studies to improve our understanding of the abundance, life history, and potential limiting factors of bull trout in the Hood River recovery unit. This report describes our findings, summarizes previous studies in the context of new information, and recommends a standardized monitoring protocol and future research. Our specific study objectives were as follows: 1. Assess adult abundance of the Clear Branch local population and develop a monitoring protocol to track abundance trends that is statistically reliable, cost-effective, and that minimizes potential adverse effects on this small isolated population. 2. Describe the juvenile and adult life history patterns of the Clear Branch local population. 3. Assess the potential impact of smallmouth bass on bull trout in Laurance Lake reservoir. 4. Determine current distribution of bull trout reproduction and early rearing in potential bull trout streams in the Hood River basin. 5. Describe the migratory life history of Hood River bull trout and assess the potential impacts of Coe Diversion and two new falls on the Middle Fork Hood River (scoured by the November 2006 glacial outburst) on bull trout migrations.

Purpose:

Time Period of Content:

Geographic Extent: Hood River Basin

Status: Final

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Format: PDF File

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Is a physical copy maintained for reference at Headquarters? Yes