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Ephrata, WA, United States

Pearsons T.N.,Grant County Public Utility District
Transactions of the American Fisheries Society | Year: 2010

We evaluated the changes in (1) the abundance, size, and biomass of rainbow trout Oncorhynchus mykiss, (2) the abundance of spring Chinook salmon O. tshawytscha parr, and (3) the combined biomass of rainbow trout and Chinook salmon parr after nine annual releases of approximately 250,000 Chinook salmon and coho salmon O. kisutch smolts into the North Fork of the Teanaway River, Washington. The trout and salmon were sampled in two treatment locations consisting of five sites and three control locations consisting of seven sites before (1990-1998) and during hatchery releases (1999-2007). We detected statistically significant decreases of rainbow trout abundance and biomass in both treatment streams relative to two of the three control streams. Furthermore, all of the differences in abundance between treatment and control streams were in the negative direction. All but one of the differences in biomass was negative. The only statistically significant change in the combined biomass of spring Chinook salmon parr and rainbow trout before and during supplementation was negative, and five of the six differences in combined biomass were negative. Only one of the four comparisons of the ratio of the log-transformed weight to length of rainbow trout was statistically significant, and it decreased during supplementation; one-half of the comparisons were positive and the other half negative. The changes to rainbow trout abundance and biomass were probably the result of the cumulative impacts from hatchery-released Chinook salmon smolts and an increase in naturally produced Chinook salmon parr. © Copyright by the American Fisheries Society 2010. Source


Pearsons T.N.,Grant County Public Utility District
Environmental Biology of Fishes | Year: 2012

Hatchery cultured salmon have the potential to interact strongly with other valued fish taxa (non-target taxa; NTT) in the natural environment. Monitoring and managing adverse interactions between hatchery supplemented salmon and NTT is one unique characteristic of a hatchery salmon supplementation program in the Yakima River, Washington. In this study, we evaluate impacts of spring Chinook salmon Oncorhynchus tshawytscha and coho salmon O. kisutch reintroduction to 15 NTT after 11 years of stocking approximately one million yearling smolts annually in the upper Yakima Basin between 1999 and 2009. Our risk management monitoring indicated changes in important response variables for NTT were within acceptable limits. Rigorous pre-implementation planning likely prevented many undesirable ecological impacts from the hatchery supplementation program. We illustrate a number of important features associated with risk management of hatchery and wild fish interactions. First, pre-project planning can eliminate many risks of concern and substantially reduce the need for risk containment during project implementation. Second, the sieve approach for monitoring impacts provided an acceptable balance between monitoring effort and risk containment ability, although in some cases, we would not detect impacts of interest. Third, rare and disbursed species that cannot be monitored effectively benefit from risk averse hatchery release strategies. Fourth, risk containment monitoring programs can be used to refute unsubstantiated claims of undesirable impacts. In short, our experience suggests that risk management of ecological interactions can occur by using a combination of pre-project adjustments through risk assessment and risk reduction, and by cost-effective risk containment monitoring and management. © 2011 Springer Science+Business Media B.V. 2011. Source


Dittman A.H.,National Oceanic and Atmospheric Administration | Pearsons T.N.,Grant County Public Utility District | May D.,University of Washington | Couture R.B.,Oregon State University | Noakes D.L.G.,Oregon State University
Fisheries | Year: 2015

Straying by hatchery-reared salmon is a major concern for conservation and recovery of many salmon populations. Fisheries managers have attempted to minimize negative ecological and genetic interactions between hatchery and wild fish by using parr-smolt acclimation facilities to ensure successful olfactory imprinting and homing fidelity. However, the effectiveness of offsite acclimation for returning adults to targeted locations has been mixed. Since laboratory and field studies indicate that the period of hatching and emergence from the natal gravel is a sensitive period for olfactory imprinting, we propose an alternative imprinting approach wherein salmon are exposed as embryos to targeted waters transferred to their rearing hatchery. To test the feasibility of this approach, we conducted a series of electrophysiological and behavioral experiments to determine whether water can be successfully transferred, stored, and treated for pathogens without jeopardizing its chemical integrity. Stream water could be frozen or stored for one week at 4° or 10° C without affecting the olfactory signature. Ultraviolet light treatment altered the responses of the olfactory epithelium to stream water; however, behavioral studies suggested that this treatment did not alter the attractiveness of this water. Finally, we describe several alternative approaches to embryonic imprinting using artificial odors. © 2015, American Fisheries Society. Source


Annual differences in ecological interactions between hatchery origin fish and the taxa that interact with them should be considered when managing hatcheries because of the potential for impacts to target and non-target taxa (i.e., taxa that are not the target of a management action). A major component of the traditional hatchery paradigm is to release approximately the same number of fish of the same species every year from the same location(s) regardless of ecological conditions. This paradigm occurs in integrated and segregated hatchery programs and generally ignores ecological feedback mechanisms within the environment that can reduce survival of hatchery and wild fish. In addition, it assumes that the carrying capacity of the environment is static and underseeded, which if incorrect can result in replacement of wild fish by hatchery con-specifics. Furthermore, practitioners of the paradigm may not consider impacts to other species that are not the target of enhancement or assumes impacts to be acceptable. To address these issues, I describe an alternative approach that prescribes stocking in places and times when: (1) ecosystem indicators suggest that risks to non-target taxa are acceptable, (2) the environment is near or below carrying capacity or density-dependent impacts are considered acceptable, and (3) ecological feedback mechanisms are in a desirable state. Indicators can also be used to refine fish rearing and stocking practices to enhance ecosystem benefits. According to this concept, fish would not be stocked in places and at times where ecosystem indicators are unfavorable. Although there are many potential ecological, genetic, and economic benefits of context-specific hatchery releases, the concept should be tested before it is applied broadly. This concept may be untenable in areas with legally-mandated release locations and numbers, or unnecessary for hatchery programs where all management goals are met. Source


Cram J.M.,University of Washington | Torgersen C.E.,U.S. Geological Survey | Klett R.S.,University of Washington | Pess G.R.,National Oceanic and Atmospheric Administration | And 3 more authors.
Environmental Biology of Fishes | Year: 2013

Spawning site selection by female salmon is based on complex and poorly understood tradeoffs between the homing instinct and the availability of appropriate habitat for successful reproduction. Previous studies have shown that hatchery-origin Chinook salmon (Oncorhynchus tshawytscha) released from different acclimation sites return with varying degrees of fidelity to these areas. To investigate the possibility that homing fidelity is associated with aquatic habitat conditions, we quantified physical habitat throughout 165 km in the upper Yakima River basin (Washington, USA) and mapped redd and carcass locations from 2004 to 2008. Principal components analysis identified differences in substrate, cover, stream width, and gradient among reaches surrounding acclimation sites, and canonical correspondence analysis revealed that these differences in habitat characteristics were associated with spatial patterns of spawning (p < 0. 01). These analyses indicated that female salmon may forego spawning near their acclimation area if the surrounding habitat is unsuitable. Evaluating the spatial context of acclimation areas in relation to surrounding habitat may provide essential information for effectively managing supplementation programs and prioritizing restoration actions. © 2012 Springer Science+Business Media B.V. Source

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