Conference Paper

Spawning Migrations of American Shad in the Columbia River

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Abstract

We sampled American shad, Alosa sapidissima, in the Columbia and Snake Rivers during 2005-2007 & 2010 to characterize basic migration biology of the population, as a model system to test general migration ecology hypotheses, and to determine if dam passage metrics for shad in the Columbia River are better than those for eastern United States populations, which are imperiled. We PIT-tagged and released 2496 adults during the 2005-2007 study period. We simultaneously determined length, mass, sex, age and spawning history (from scales) and energetic status (using a Fatmeter) for a subset of PIT tagged fish in an effort to relate individual traits to migration behavior. Collections of adults at Bonneville and Lower Granite dams and of juveniles at six lower Columbia and Snake river dams characterized seasonal and longitudinal patterns during upstream and downstream migration, respectively. Analyses demonstrated that: 1) individual adults returned to the Columbia Basin spawn in multiple years; 2) the adult populations at Lower Granite Dam (rkm 695) were younger and male-biased compared to adults at Bonneville Dam (rkm 235); 3) that mean initial lipid content of adults detected at McNary Dam (rkm 470) was higher than adults detected only at Bonneville Dam; and 4) juvenile growth rates were higher in upstream reaches of the basin, particularly in the Snake River reservoirs. In 2010, we radio- and PIT-tagged 234 adult fish to estimate individual passage behavior and success at the four lower Columbia River dams. A total of 26% of the tagged fish passed Bonneville Dam. A total of 78% of the fish passing Bonneville Dam passed The Dalles Dam, 45% of those passed John Day Dam, and 48% of those passed McNary Dam. A seasonal effect was evident, with 57% of the fish tagged in the early part of the run passing Bonneville Dam, compared to 18 and 4% during the middle and late parts of the run. Collectively, the results suggest that: 1) shad passage behavior and performance at dams differ from salmonids; 2) that adult upstream migration behavior appears to be relatively flexible, may be dependent on life history stage and/or initial condition of individuals, and may affect offspring growth and survival; 3) the ecological effects of adults in reservoirs differs longitudinally; and 4) indicate greater passage success than observed in East Coast rivers.

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Maltais E, Daigle G, Colbeck G, Dodson JJ. Spawning dynamics of American shad (Alosa sapidissima) in the St. Lawrence River, Canada–USA. Ecology of Freshwater Fish 2010: 19: 586–594. © 2010 John Wiley & Sons A/SAbstract –  The most northerly population of American shad (Alosa sapidissima), located in the St. Lawrence River, is considered vulnerable because of low population abundance and limited spawning habitat located at the upstream extent of the population’s anadromous migration. Here, we aimed to establish the temporal and spatial extent of spawning based on a novel hatch-date analysis of juveniles. Spawning activity lasted from early May to early July. We found that juveniles captured downstream during the summer hatched later in the year than those captured further upstream. As a result, younger juveniles were distributed somewhat further downstream. In addition, we found significant multimodality in hatch-date distributions at midstream and downstream sampling stations. Together, these results provide evidence that the 2-month spawning period involved numerous spawning events that progressed in a downstream direction as the season advanced, rather than being restricted to upstream sites over the spawning season.
Adaptive fishway design: a framework and rationale for effective evaluations. Monitoring, Funktionskontrollen und Qualitätssicherung an Fischaufstiegsanlagen. 2. Kolloquium zur Herstellung der ökologischen Durchgängigkeit der Bundeswasserstraßen
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