Duncan Creek, a Washington tributary that enters the Columbia at River Mile 140 (approximately 6 miles downstream from Bonneville Dam) was an important spawning area for chum salmon.  In 1951, for example, over 500 chum salmon were observed in Duncan Creek. In 1963, a dam was placed near the mouth of the creek and a culvert was installed for fish passage.  However, chum returns rapidly declined after the dam was built and by 1969 no chum were found in the basin.

A three-pronged approach is being used to once again produce a self-sustaining chum salmon population in Duncan Creek. This approach included modifying the dam, enhancing spawning habitat, and using local brood stock to re-introduce chum back into the basin.

The first objective was accomplished in November 2000, when the dam was modified to allow fish passage.  The structure cost approximately $500,000 including a $131,106 self-assessment by the Skamania Landing Owners Association (SLOA).  Washington Department of Fish and Wildlife (WDFW) and SLOA obtained the balance from non-federal sources including the State of Washington Governor's Salmon Recovery Office, Salmon Recovery Funding Board, Washington Department of Natural Resources Aquatic Lands Enhancement Account, and the National Fish and Wildlife Foundation.  The second objective was accomplished in November 2001 when the spring/seep areas that chum historically spawned in Duncan Creek were cleaned of sediment, debris and reed canary grass and suitable spawning gravel was placed back into these areas.  The third objective began in November/December 2001 when adult chum were placed into the renovated channels to spawn naturally.  Concurrently, adult chum were taken to Washougal Hatchery to be artificially spawned to provide fed-fry for release at the mouth of Duncan Creek.

For FY 06, this project addresses the continued collection of brood stock and outlines a comprehensive plan for monitoring and evaluating the Duncan Creek chum re-introduction.  Adults will be collected from volunteers to Duncan Creek, adjacent chum salmon stocks, e.g. Hardy and Hamilton creeks, and the mainstem of the lower Columbia River including individuals salvaged from higher water elevations in the Ives Island area (i.e. areas that may not be protected through 100% emergence by mainstem flows).  These adults will either be placed in the rejuvenated channels to naturally spawn or artificially spawned at Washougal Hatchery.  During the incubation period for artificially produced fry, thermally produced bar codes will be induced into the otoliths of the developing embryos.  After hatching, the fry will be reared for approximately six weeks and released at night.  Naturally produced fry are be trapped as they out-migrate and will be marked by via immersion in a solution of strontium chloride hexahydrate.  Marking of naturally produced fry with strontium chloride hexahydrate is conducted under an Investigative New Animal Drug (INAD) permit issued by the FDA in 2003.  Otolith marks will be utilized to estimate fry-to-adult survival rates of both artificially and naturally produced fish.  Otolith marks and accurate population estimates will be used to estimate straying rates and percent contribution of Duncan Creek project origin adults to other Lower Gorge chum spawning locations.  The occurrence of non-marked adult chum recovered in Duncan Creek will be used to estimate how quickly wild fish are re-colonizing the stream.  Beginning in the fall of 2004, adult chum originating from this project will start returning to Duncan Creek.  They will either be allowed to spawn naturally in the rejuvenated spawning habitat or used as part of the hatchery broodstock program.  The physical conditions in this part of the stream will be monitored and egg-to-fry survival rates will be determined.

The newly established habitat and the reintroduction effort will both provide clear survival benefits to Columbia River chum salmon returning to the Bonneville area and demonstrate the effectiveness of these kinds of reintroduction efforts.  Methods employed and associated results can be used as a template for future reintroduction efforts for Columbia River chum salmon.


Background

In the early twentieth century hundreds of thousands of chum salmon returned to Lower Columbia River tributaries and mainstem spawning sites.  Since then habitat alterations leading to dynamic flow regimes, riverbed movement and heavy siltation have been largely responsible for the decline of this species in the Columbia River.  The few stable spawning areas that still exist are often in danger of being destroyed by flood events, development, or dewatering due to hydropower demands or climatic variation.  Low water years, such as that experienced in 2001 and 2002, and fluctuating flows may limit access to spawning areas below Bonneville Dam preventing successful spawning and potentially creating overcrowded conditions in available areas.

In March 1999, the National Fisheries Service listed Lower Columbia River chum salmon as a threatened species under the auspices of the Endangered Species Act (ESA).  In 1994, using allozyme analysis, only two genetic enclaves of Lower Columbia River chum salmon were recognized, a population that returns to the Grays River and a constellation of stocks that spawn just below the Bonneville Dam, e.g. in Hardy and Hamilton Creeks and also adjacent to Ives Island.  More recently in 2004, WDFW geneticist reported that microsatellite DNA analysis suggest that there are three genetically differentiated chum salmon groups in the lower Columbia River, each associated with an ecological region: a Coastal group, a Cascade group and a Columbia Gorge group.

Duncan Creek, a Washington tributary that enters the Columbia at river mile 140, was historically an important spawning area for chum salmon.  Surveys conducted in 1951 by the Washington Department of Fisheries found over 500 chum salmon utilizing the natural springs in Duncan Creek for spawning.  Duncan Creek has a high concentration of natural seeps, is a relatively short watershed and has a low gradient; all of which make it an ideal spawning location for chum salmon.  Geographically, Duncan Creek is very similar to Hardy and Hamilton creeks.  In 1963, a dam was placed near the mouth of the creek and a culvert was installed for fish passage.  However, chum returns rapidly declined, and by 1969 chum were no longer using this basin.  Landowner agreements and dam modifications completed in the fall of 2000 re-opened Duncan Creek to chum salmon.  Restoration of three spring channel reaches historically used by chum salmon was completed in November 2001.  With passage issues solved and rejuvenated spawning areas available, reintroduction along with monitoring and evaluation efforts began in the fall of 2001.

The Lower Columbia River and Columbia River Estuary Subbasin Summary (Subbasin Summary) prepared for the Northwest Power Planning Council (NWPPC) states that chum salmon stocks in the Columbia River basin have declined to less than 1% of historic levels.  The Subbasin Summary provides a synopsis of the Limiting Factors Analysis completed by the Washington State Conservation Commission for the Bonneville Tributaries Subbasin (2000).  Limiting factors addressed by this proposal include:  (1) the limited amount of lower gradient habitat for spawning and rearing of anadromous salmonids within the subbasin, (2) the accumulation of fine sediments in the spring-fed areas of Duncan Creek, and (3) the lack of water quality data within the subbasin.  This proposal also addresses the general information needs identified in the Subbasin Summary for the reintroduction of chum salmon into Duncan Creek.  These needs include an examination of  (1) egg-to-fry survival rates in the rejuvenated stream channels, (2) survival of eggs and fry used in the artificial rearing program, (3) survival, percent contribution to and spawning ground distribution of adult chum salmon produced from the rejuvenated habitat areas and from the artificial rearing program, (4) the straying rate of non-project chum into Duncan Creek, and (5) the physical characteristics present in the rejuvenated portions of Duncan Creek.  This information will help to answer questions about how well chum salmon native to the Columbia River survive in the rejuvenated areas, and whether the habitat maintains its productive status.

Water levels in the lower Columbia River in the summer of 2001 were the second lowest on record.  At that time, it was feared that if conditions persisted into November and December returning chum salmon would encounter limited access to spawning areas.  During low water conditions, the chum population below Bonneville is the most at risk, as low water in Hamilton and Hardy Creeks may create a complete barrier to fish passage, while much of the Ives Island spawning area may be too low for successful spawning, if not completely un-watered.  The I-205, Multnomah and St. Cloud subpopulations may also be threatened if near-shore seep areas are not accessible.  Allowed to fare on their own, these populations may experience overcrowding resulting in high instantaneous and overall densities on the spawning grounds.  High instantaneous densities can result in high egg retention rates and promote superimposition of redds.  High overall density can result in redd superimposition and egg loss due to mechanical agitation or being uplifted by spawning activities of later spawning females.  Under extreme conditions these and related factors may cause brood year failures.


In response to the situation, the Bonneville Power Administration (BPA) requested the Washington Department of Fish and Wildlife (WDFW) generate a chum salmon "salvage" plan outlining potential options for emergency intervention.  A plan was developed (Chum Salmon Salvage Plan:  Fall 2001) with the goal of preserving genetic diversity within the population by ensuring adequate numbers of chum salmon survived to spawn successfully, either naturally or artificially.  The plan outlines options for expanding the Duncan Creek reintroduction brood stock collection protocol to encompass other areas determined to be at risk (Table 1).  The plan was submitted as an addendum to the Duncan Creek reintroduction project and was incorporated into the Hatchery Genetic Management Plan (HGMP) for Washougal Hatchery chum salmon.


Table 1.  Summary of strategies for Columbia River Chum Salmon salvage plan.
Case   Columbia River   Tributaries     Spawning area                             Strategy
  1          low      low              low        Juvenile supplementation in the mainstem Columbia River and  tributaries
  2          low      low          adequate        Adult supplementation in tributaries and juvenile supplementation in the mainstem Columbia River
  3       adequate      low              low        Juvenile supplementation in tributaries, and no action in the mainstem Columbia River
  4          low adequate         adequate        Juvenile supplementation in the mainstem Columbia River, and no action in tributaries
  5       adequate adequate         adequate        No intervention, rely on natural production, and monitor


Our current proposal proposes to continue the collection of brood stock for the Duncan Creek reintroduction project and activities related to the monitoring and evaluation plan designed to assess the viability of these strategies for reintroduction of chum salmon into other Columbia River tributaries.