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wildthing@dfw.wa.gov

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360-902-2534
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Lead Scientist: Kelly Kiyohara

Ecoregions: Puget Trough

   
  Click on map to enlarge
Click on map to enlarge
   

Freshwater Production and Survival of Puget Sound Salmonids

Lake Washington Sockeye and Chinook Evaluation

Project Description

Location: The Cedar inclined-plane trap is located near the mouth of the Cedar River roughly river mile 0.8, near Renton; screw trap at river mile 1.6, near the I-405 overpass. The Bear Creek screw trap is located at river mile 1.0, near Redmond, Washington. (see map)

History: In 1992, the Washington Department of Fish and Wildlife (WDFW), through funding from King County, initiated an evaluation of sockeye fry migrants in the Cedar River to investigate the causes of low adult sockeye returns. In 1999, the Cedar River juvenile monitoring study was expanded in scope in order to include juvenile migrant Chinook salmon in response to being listed as “threatened” under the authority of the Endangered Species Act (NMFS 1999). This new scope extended the trapping season to a six month period and, as a consequence, also allowed production estimates to be derived for coho, steelhead, and cutthroat trout.

In 1997, WDFW initiated an evaluation of sockeye fry migrants in the Sammamish basin. In 1997 and 1998, a juvenile trap was operated in the Sammamish River during the downstream sockeye migration. While this operation was successful in estimating sockeye fry production, velocities in the Sammamish were too low to capture larger migrant species. In 1999, this monitoring study was moved to Bear Creek in order to simultaneously evaluate Chinook and sockeye production. Since 1999, through funds from King County and the King Conservation District, the Bear Creek juvenile monitoring study has also provided production estimates to be derived for coho, steelhead, and cutthroat trout.

In addition to the juvenile trapping, in 1994 WDFW started a project to assess juvenile salmon passage through the Ballard Locks.  With the cooperation of the US Army Corps of Engineers (USACE), the Muckleshoot Tribe and National Marine Fisheries (NMFS), a multi -agency research team studied juvenile salmon passage through the Locks.  As a result, significant changes were made to operations and facilities to improve the survival of juvenile salmon exiting Lake Washington.

In 2001, in cooperation with the USACE, a portion of the juvenile Chinook and coho from both traps were implanted with Passive Integrated Transponder (PIT) tags to evaluate migration timing and survival through Lake Washington to the Ballard Locks. Subsequent years tagging has occurred through continued funding by King County and the King Conservation District.

As part of a multi-stage assessment of sockeye survival through Lake Washington, survival of sockeye smolts from lake entry, through their first year in the lake, is also monitored as migration occurs out of Lake Washington. Beginning in 2004, WDFW, through funding from Seattle Public Utilities, has been collecting sockeye smolts, using a modified purse seine, to estimate relative survival of natural and hatchery origin sockeye and to evaluate various hatchery rearing and release strategies via otolith analysis. The otolith of natural origin sockeye and each rearing/release group of hatchery sockeye are uniquely marked based on the water temperatures experienced during egg incubation, allowing for each fish to be assigned as either natural origin or hatchery, and also to which hatchery rearing and release strategy the fish experienced. Seining efforts have continued through Seattle Public Utilities support.

Objectives

Primary objectives:

  • CHINOOK:

    • Estimate in-river survival. In-river survival is estimated from production of juvenile migrants and estimated egg deposition. Correlation between in-river survival and variables such as spawner abundance, discharge, and habitat condition will identify density dependent and independent factors limiting juvenile production.
    • Determine variables contributing to juvenile production. Identifying variables that limit production of both life history stages may inform management on the current carrying capacities for each watershed.
    • Estimate contribution of lake/marine survival on spawner abundance. Survival from river outmigration to returning spawners indicates the relative contribution of early riverine survival to lake/locks/marine survival for Chinook abundance.
    • Identify variables contributing to life history diversity. Sub yearling Chinook migrate at two different life stages, fry and parr. Identifying habitat or climatic variables that contribute to Chinook life history diversity will develop recovery strategies that support each life history type.
  • SOCKEYE
    • Estimate in-river survival. Overall success of natural spawning sockeye will be determined from natural-origin fry production and estimated egg deposition. Variation in survival among broods, as a function of spawner abundance and flows will be evaluated to assess stream carrying capacity and the relative importance of environmental variables.
    • Estimate incidence of hatchery fry entering Lake Washington from the Cedar River. Relative survival of hatchery and natural-origin sockeye can be determined by comparing the proportion of hatchery and natural-origin sockeye at the fry life history stage with proportions at later life stages (smolts and adults).
    • Compare migration timing of natural-origin and hatchery fry. Environmental predictors of the migration timing for natural-origin sockeye fry will contribute to in-season decisions on hatchery releases and allow in-season estimates of the abundance of natural-origin fry. A comparison of migration timing and subsequent survival of hatchery versus natural-origin sockeye fry will contribute to the adaptive management process guiding the production and release of Cedar River Hatchery sockeye fry.

Secondary objectives:

  • Estimate production of coho, cutthroat, and steelhead/rainbow smolts, when possible, to provide a measurement of ecosystem health in the Cedar River and Bear Creek. Population levels and ratios between these species are indicative of habitat conditions and responses to watershed management.

Key Findings
Click on graphs to enlarge

Dungeness River Wild Chinook Sub Yearling Production Graph

Cedar River Sockeye

Over the course of trapping since 1992, annual freshwater production of Cedar River natural-origin sockeye has been inconsistent ranging from 730,000 to 38.6 million sockeye. Production has been correlated with the number of returning adults that spawn the previous fall and river discharge during the egg incubation period (November through January). Annual sockeye survival from egg deposition in the fall to migration between January and June ranges from 1.91% to 56.6%.  Migration timing has been correlated with water temperatures during the egg incubation period.  Warmer incubation temperatures lead to earlier emergence and migration.


Dungeness River Wild Chinook Sub Yearling Production Graph

Cedar River Chinook

In the Cedar River Chinook salmon migrate in their first year. Cedar River natural-origin Chinook freshwater production has ranged from 32,000 to 769,000 since 1999.  The Chinook in the Cedar River migrate during their first year in two major pulses. The first pulse consists of smaller Chinook that migrate as fry and exit the river between January and April. The second pulse is comprised of larger Chinook that stay in the river to rear and migrate as parr from May to July.  Annual survival of Chinook from egg deposition in the fall to migration which occurs from January through July is 4.7% to 19.2%.


Dungeness River Wild Chinook Sub Yearling Production Graph

Cedar River Coho

Cedar River natural-origin coho freshwater production declined dramatically during the mid-2000’s but over the past two years have rebounded to early 2000 levels. Annual production has ranged from 13,000 to 83,000.


Dungeness River Wild Chinook Sub Yearling Production Graph

Bear Creek Sockeye

Bear Creek sockeye production has been variable since monitoring began in 1999.  The 2007 migration was substantially greater than other years.  Annual freshwater production has ranged from 129,000 to 5.9 million sockeye.  Survival from egg deposition to migration ranges from 3.0% to 36.2%


Dungeness River Wild Chinook Sub Yearling Production Graph

Bear Creek Chinook

Bear Creek natural-origin Chinook freshwater production has been variable since trapping began in 1999.  Annual production has ranged from 9,000 to 65,000.  Unlike the Cedar River where Chinook migrate as fry and parr, Chinook in Bear Creek predominantly migrate as parr. Survival of Chinook in Bear Creek from egg deposition to migration ranges from 1.0% to 11.0%


Dungeness River Wild Chinook Sub Yearling Production Graph

Bear Creek Coho

Annual natural-origin coho freshwater production in Bear Creek shows high variability. Production has ranged from 12,000 to 62,000 over the course of trapping.

Data - data is in MS Excel format

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