Susan A. Hinton

Distribution and Migration of Juvenile Chinook Salmon Derived from Coded Wire Tag Recoveries along the Continental Shelf of Western North America

Abstract The effects of ocean conditions on highly migratory species such as salmon are difficult to assess owing to the diversity of environments they encounter during their marine life. In this study, we reconstructed the initial ocean migration routes of juvenile Chinook salmon Oncorhynchus tshawytscha originating from Oregon to Southeast Alaska using coded wire tag recovery data from Canadian Department of Fisheries and Oceans and National Marine Fisheries Service research surveys conducted between 1995 and 2006. Over this 12-year period, 1,862 coded-wire-tagged juvenile Chinook salmon were recovered along the coasts of Oregon, Washington, British Columbia, and Alaska from March to November. Except for those from the Columbia River, most juvenile Chinook salmon remained within 100–200 km of their natal rivers until their second year at sea, irrespective of their freshwater history and adult run timing. Northward migration of most coastal stocks was initiated during their second or possibly third year ...

Distribution of the invasive New Zealand mudsnail ( Potamopyrgus antipodarum ) in the Columbia River Estuary and its first recorded occurrence in the diet of juvenile Chinook salmon ( Oncorhynchus tshawytscha )

Estuaries play an important role as nurseries and migration corridors for Chinook salmon and other fishes. The invasive New Zealand mudsnail, Potamopyrgus antipodarum (Gray, 1843), has been noted in the Columbia River Estuary and other estuaries in the western USA, yet no studies have addressed the estuarine impacts of this invader. Our data show P. antipodarum is currently found in five peripheral bays and many tributaries of the Columbia River Estuary, where it can constitute a major portion of the benthic invertebrate biomass and where it co-occurs with native amphipod species. We review the history of the P. antipodarum invasion in the Columbia River Estuary and discuss potential impacts on estuarine food webs. We also report the first occurrence of P. antipodarum in the diet of juvenile Chinook salmon from the Columbia River Estuary. Although present in Chinook diets at very low frequencies, our observations of P. antipodarum in Chinook gut contents may represent early stages of food web change due to the establishment of dense estuarine snail populations. Additional research is needed to determine the effects of P. antipodarum on benthic resources, native benthic invertebrates, and benthic predators. We encourage biologists working in western USA estuaries to be alert to the possibility of encountering P. antipodarum in benthic habitats and predator diets.

Early Ocean Dispersal Patterns of Columbia River Chinook and Coho Salmon

AbstractSeveral evolutionarily significant units (ESUs) of Columbia River asin Chinook Salmon Oncorhynchus tshawytscha and Coho Salmon O. kisutch are listed as threatened or endangered under the U.S. Endangered Species Act. Yet little is known about the spatial and temporal distributions of these ESUs immediately following ocean entry, when year-class success may be determined. We documented differences in dispersal patterns during the early ocean period among groups defined by ESU, adult run timing, and smolt age. Between 1995 and 2006, 1,896 coded-wire-tagged juvenile fish from the Columbia River basin were recovered during 6,142 research trawl events along the West Coast of North America. Three distinct ocean dispersal patterns were observed: (1) age-1 (yearling) mid and upper Columbia River spring-run and Snake River spring–summer-run Chinook Salmon migrated rapidly northward and by late summer were not found south of Vancouver Island; (2) age-0 (subyearling) lower Columbia River fall, upper Columbia ...

Genetic Identification of Chinook Salmon in the Columbia River Estuary: Stock-Specific Distributions of Juveniles in Shallow Tidal Freshwater Habitats

AbstractExtensive efforts are underway to restore and conserve nearshore shallow water habitats in the Columbia River estuary with the intent of increasing the estuarys capacity to provide food, refuge, and other crucial ecosystem functions for juvenile salmon. Juvenile Chinook Salmon Oncorhynchus tshawytscha, including those from the five Evolutionarily Significant Units listed as threatened or endangered under the U.S. Endangered Species Act, are particularly expected to benefit from the habitat improvements. However, information on the temporal and spatial estuarine distributions of juveniles from specific populations or stocks is lacking and impedes restoration planning for at-risk salmon. We conducted a series of surveys to sample juvenile Chinook Salmon occupying shallow-water habitats with sandy beaches in six hydrogeomorphic reaches across the tidal freshwater portion of the estuary and also at one long-term reference site near the estuary mouth. Sites were sampled bimonthly over 26 months during...

Stock-Specific Size and Timing at Ocean Entry of Columbia River Juvenile Chinook Salmon and Steelhead: Implications for Early Ocean Growth

Abstract Juvenile salmon transitioning from freshwater to marine environments experience high variation in growth and survival, yet the specific causes of this variation are poorly understood. Size at and timing of ocean entry may contribute to this variation because they influence both the availability of prey and vulnerability to predators. To explore this issue, we used stock assignments based on genetic stock identification and internal tags to document the stock-specific size and timing of juvenile hatchery and presumed wild Columbia River Chinook Salmon Oncorhynchus tshawytscha and steelhead O. mykiss at ocean entry during 2007–2011. We found that juvenile salmon and steelhead had consistent stock-specific capture dates, with lower-river stocks typically having earlier timing than those originating farther upstream. Mean size also varied among stocks and was related to hatchery practices. Hatchery yearling Chinook Salmon and steelhead were consistently larger than wild fish from the same stocks, although timing in the estuary was similar. In contrast, hatchery subyearling Chinook Salmon were of similar size to wild fish but entered the ocean up to a month earlier. We evaluated the potential importance of these traits on early marine growth by estimating stock-specific growth rates for Chinook Salmon caught in estuarine and ocean habitats. Growth rates were related to relative ocean entry timing, with lower growth rates for stocks that had only recently arrived in marine waters. Our results demonstrate that stocks within a single basin can differ in their size and timing of ocean entry, life history traits that contribute to early marine growth and potentially to the survival of juvenile salmon. Our results also highlight the necessity of considering stock-specific variation in life history traits to understand salmon ecology and survival across the entire life cycle.

Introduction of a Siberian Freshwater Shrimp to Western North America

Robert L. Emmett1,∗, Susan A. Hinton1, Daniel J. Logan2 & George T. McCabe, Jr.1 1Northwest Fisheries Science Center, National Marine Fisheries Service, 2725 Montlake Blvd, East Seattle, WA 98112-2097, USA; 2National Marine Fisheries Service, Protected Resources Division, 777 Sonoma Street, Room 325 Santa Rosa, CA 95404, USA; *Author for correspondence (e-mail: robert.emmett@noaa.gov; fax: +1-541-867-0389)