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The impacts of exotic species on native fish assemblages

The impacts of exotic species on native fish assemblages. By: Heather Bradley, James Hulslander & Katie McGohan. Photo by: Heather Bradley. Sources of exotic species to lakes. Accidental Ballast water Bait bucket dumping Aquaria Intentional Game fish stocking

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The impacts of exotic species on native fish assemblages

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  1. The impacts of exotic species on native fish assemblages By: Heather Bradley, James Hulslander & Katie McGohan Photo by: Heather Bradley

  2. Sources of exotic species to lakes • Accidental • Ballast water • Bait bucket dumping • Aquaria • Intentional • Game fish stocking • Unofficial stocking by locals

  3. Research Questions • Does the number of native fish species in a lake decrease as the number of exotic fish species increases? • What impact do exotic species have on overall biodiversity within the lake? • Which habitats support more diverse fish communities?

  4. Why ask these questions? • Large predatory fish stocking • Native fish are likely to be out competed or consumed by these predators • Exotics may not have natural predators in the new system they are introduced to

  5. How to answer these questions? • Go Fishing! • Trap nets, Gill nets and minnow traps • Cover as many habitat types within the lake as possible • Catch LOTS of fish (and their delightful parasites)

  6. Methods continued…. • Sample the invertebrates of the lake • Important for assessing food availability and making comparisons between lakes • Plankton tows, Ekman grab samples

  7. Diversity by Lake

  8. Diversity by Lake and Habitat

  9. Diversity Results • Wolf Lake highest richness • Wolf Lake highest Shannon Diversity (eveness considered) • Cranberry highest Simpson’s

  10. Catlin Lake Biomass

  11. Cranberry Lake Biomass

  12. Conclusions • Exotic species impact fish species diversity • Wolf lake highest richness and diversity when evenness included • Biomass for native vs exotic species even for Catlin and Cranberry • 3 habitats vary in diversity but vegetated highest richness

  13. Suggestions • Other sampling techniques for larger fish (gillnets, deeper water sets, rods) • More Samples collected in: • Varying weather • Huntington lakes • Seasons • More habitats

  14. Sources of Error • Incorrect ID • Digital scales not working properly • Dead/mangled/rotting samples • More sampling of Cranberry • Net holes and mistakes

  15. Treatment • Education of public • Biological Control? • Chemical treatments

  16. Questions???

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