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

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Alewife in lake champlain

Alewife in Lake Champlain

A serious problem, seriously

David Brownlow, Natalia Fajardo,

April Kane, William Wilson III


Problem statement
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
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.




Objectives
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


Stakeholders
Stakeholders

  • USFWS

  • VTDFW

  • Quebec Ministry of Nat. Resources

  • NY - DEC

  • Lake Champlain Basin Program

  • Fishermen

  • Recreational Users (swimmers)


Background
Background

  • Alewife Biology

  • Alewife in Vermont

  • Possible Modes of Entry


Alewife biology
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.


Alewife biology1
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


Alewife in vermont
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



Possible modes of entry
Possible Modes of Entry

  • Canals

    • Saint Lawrence Seaway

    • Lake St. Catherine via

    • Champlain Barge Canal


Possible modes of entry1
Possible Modes of Entry

  • Accidental Release

    • Alewife are common bait

    • First specimen found in Missisquoi Bay, indicating accidental release as mode of entry


Thiamine deficiencies
Thiamine Deficiencies

  • Alewife contain thiaminase

  • Predators experience decreased thiamine

  • Leads to Early Mortality Syndrome


Ecological effects case studies
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



Otsego lake new york1
Otsego Lake, New York

  • 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



Lake michigan1
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


Lake michigan2
Lake Michigan

  • Long-tern surveillance of alewife essential to understanding lake dynamics


Management options
Management Options

  • Two primary methods to reduce or control alewife population

    • Population reduction

      • Netting

      • Predation

    • Reclamation


Management options1
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


Management options2
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


Conclusion
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


Acknowledgments
Acknowledgments

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

Questions?


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