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Incidence of Predation on Chum Salmon Fry in Marine Waters near Juneau

Incidence of Predation on Chum Salmon Fry in Marine Waters near Juneau. Craig Farrington Alaska Dept of Fish & Game The Southeast Sustainable Salmon Funds made this project possible. Gastric lavage apparatus, a.k.a. the Vomit-O-Matic. DIPAC fry monitoring.

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Incidence of Predation on Chum Salmon Fry in Marine Waters near Juneau

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  1. Incidence of Predation on Chum Salmon Fry in Marine Waters near Juneau Craig Farrington Alaska Dept of Fish & Game The Southeast Sustainable Salmon Funds made this project possible

  2. Gastric lavage apparatus, a.k.a. the Vomit-O-Matic

  3. DIPAC fry monitoring

  4. Relative abundance of chum fry from mid-May to mid-June in marine waters near Juneau

  5. Potential predators of salmon fry in marine waters near Juneau

  6. Salmon fry predation by species

  7. CPUE of Dolly Varden using variable mesh gillnet

  8. Cumulative percent cpue for Dolly Varden

  9. Size of Dolly Varden captured by variable mesh gillnet

  10. Condition of chum fry in stomachs

  11. Incidence of prey items in stomach contents

  12. Percent incidence of predation on wild chum fry, early vs late

  13. Conclusions (preliminary • Peak of the relative abundance of chum salmon fry (predominantly hatchery origin) in local waters is May 21 - June 1 • Wild chum fry likely appear earlier in local waters with unknown abundance and run timing • Dolly Varden char are the main early marine predators on chum salmon fry (28% incidence of chum fry in stomachs) in local Juneau waters • Dolly Varden peak abundance – May 27- and midpoint of ‘run’ – May 29 - are both concurrent with the peak residence of hatchery chum fry • Larger sized Dolly Varden in early Spring targeted chum fry; smaller sized Dolly Varden arrive later and target other smaller prey items (invertebrates) in their diets • As a prey item in the diet of Dolly Varden, the potential energetic value of chum fry is roughly 4 times that for non-chum prey items

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