Alewife in Lake Champlain

Alewife in Lake Champlain

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Problem Statement. The presence and possible reproduction of the alewives in Lake Champlain has been confirmed in recent years, which can potentially alter the zooplankton community and cause a decline in native fish stocks.. Purpose Statement. This presentation provides an assessment of the
Alewife in Lake Champlain

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1. Alewife in Lake Champlain A serious problem, seriously David Brownlow, Natalia Fajardo, April Kane, William Wilson III

2. Problem Statement The presence and possible reproduction of the alewives in Lake Champlain has been confirmed in recent years, which can potentially alter the zooplankton community and cause a decline in native fish stocks.

3. Purpose Statement This presentation provides an assessment of the impacts that alewives will likely have in Lake Champlain by integrating available information on the issue. An analysis of the possible management strategies was conducted, and preferred alternatives were proposed.

4. EPA/ERA Framework

5. EPA/ERA Framework

6. Objectives Review literature on the status of the alewife in Vermont Evaluate relevant case studies Determine potential ecological effects of alewife establishment in Lake Champlain Propose possible management practices

7. Stakeholders USFWS VTDFW Quebec Ministry of Nat. Resources NY - DEC Lake Champlain Basin Program Fishermen Recreational Users (swimmers)

8. Background Alewife Biology Alewife in Vermont Possible Modes of Entry

9. Alewife Biology Alosa pseudoharengus A member of the herring family (clupeidae) Habitat Anadromous Species Primarily found along Atlantic Coast in riverine and estuarine environments Colored dorsally grey to grey-green and laterally silver with a prominent dark shoulder spot.

10. Alewife Biology Length ? Adults are 6-12? Spawning period ? Late March thru early June Spawn in shallow lake edge waters, spend the rest of the time in the deeper water Can establish freshwater populations in large lakes

11. Alewife in Vermont Lake St. Catherine, Rutland, VT First Alewife in VT, discovered 1997 Lake Champlain Alewives identified in 2003 11 have been found to date

12. Alewife in Lake Champlain

13. Possible Modes of Entry Canals Saint Lawrence Seaway Lake St. Catherine via Champlain Barge Canal

14. Possible Modes of Entry

15. Thiamine Deficiencies Alewife contain thiaminase Predators experience decreased thiamine Leads to Early Mortality Syndrome

16. Ecological Effects ? Case Studies Otsego Lake, New York Chosen because of similar biological communities and both lakes have seasonal turnover (dimictic) Lake Michigan Similar in size and extent to Lake Champlain and very well-studied

17. Otsego Lake, New York

18. Zooplankton community changes Shift from large to small species and decreased filtering rate Algal changes Increase in nutrient cycling rate, which favors smaller algal cells Changes in fish communities Other fish species suffer from competition for plankton and predation of their fry and eggs by alewife Otsego Lake, New York

19. Lake Michigan

20. Lake Michigan Invasion by alewife resulted in declines of shiner, perch, and bloater In 1990s length of alewife decreased Not density-dependent Due to decreases in Diporeia (an alewife food source) Stocking of salmonid species effectively reduced alewife population

21. Lake Michigan Long-tern surveillance of alewife essential to understanding lake dynamics

22. Management Options Two primary methods to reduce or control alewife population Population reduction Netting Predation Reclamation

23. Management Options Netting Gillnetting, seining, electrofishing Electrofishing having success in Lake St. Catherine Has to be done both day and night during the spawning season Predation Stocking brown and rainbow trout Sustaining a viable Atlantic Salmon population problems

24. Management Options Lake reclamation (eradicating alewife population) Rotenone breaks down readily and by-products are non-toxic Antimycin breaks down more quickly than rotenone, more toxic than rotenone Have been disastrous effects in the past A mixture of all three, or just the two population reduction methods would be best

25. Conclusion Alewife population establishment is highly probable However, introduction to the Lake is recent and their effect is uncertain If Alewife proves disruptive, netting or biological control through fish stocking will become necessary

26. Acknowledgments Thanks to Bernie Pientka for sharing his expertise and providing guidance.

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