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Last modified
7/14/2009 5:01:45 PM
Creation date
5/20/2009 1:33:57 PM
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UCREFRP
UCREFRP Catalog Number
7605
Author
Schaeffer, L.
Title
Avian Predators at ODFW Hatcheries
USFW Year
1992.
USFW - Doc Type
Their Identification and Control.
Copyright Material
YES
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<br />for methods that would reduce predation if they were incorporated <br />into current release strategies. Some suggestions were: <br /> <br />1. Night releases. <br /> <br />2. Releases during freshets (into muddy water). <br /> <br />3. Coastal releases during tidal flushes. <br /> <br />4. Massive releases to overwhelm predators. <br /> <br />5. Trickle releases so as not to attract predators. <br /> <br />6. Hazing or human presence in the release area. <br /> <br />7. Releases into a pipeline to tidewater. <br />8. Acclimation ponds at tidewater or net pens in estuaries. <br /> <br />9. Clearing predators' cover. <br /> <br />10. Clearing roosting or perching places. <br />11. Providing cover in the water for fish to hide. <br /> <br />12. Releases of fish from boats in reservoirs. <br /> <br />13. For releases below dams, increasing flows in rivers. <br /> <br />14. Avoid releasing fish in areas with heavy predator <br />populations, nesting sites, or flyways. <br /> <br />Some of these strategies are currently being tried but they <br />are applicable only to certain hatcheries. Constraints such as <br />shortages of equipment, overcrowding in the hatchery, diseases, <br />and lack of satisfactory water flow can affect release <br />strategies. <br /> <br />Cost Benefit <br /> <br />Managers of 38 facilities responded to the questions about <br />costs, which ranged from $225 at Fall River Hatchery to <br />$1,000,000 at Bonneville Hatchery. Estimates of fish lost to <br />predation ranged from 500 fish at Wallowa Hatchery to 2.8 million <br />at Wahkeena Pond (Table 4). Because of manpower requirements to <br />do a detailed study, the relationship between predation and fish <br />loss has not been precisely determined. Each facility must be <br />looked at individually to determine the type and amount of <br />protection that is appropriate (Table 4). If some loss is <br />acceptable, then many different strategies are available. <br /> <br />10 <br />
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