1. Alewife: Assessment and Impacts on Lake Champlain
(Brooks and Dodson, 1965)
Marty Frye, Lecia Babeu, Will Matukonis, Zack Clark

2. Goal/Purpose Statement
We seek to understand the impacts of alewives on:
Trophic interactions
Species populations
Aquatic ecosystem balance
In Lake Champlain

3. OBJECTIVES
Select specific endpoints for assessing alewife impacts on natural systems in Lake Champlain.
Examine the effects of alewife on:
Other fish specie’s eggs and larvae
Salmonid populations  (Early Mortality Syndrome)
Zooplankton and Phytoplankton

4. Who's da Fish with da Funny Name?
   -Alosa pseudoharengus
      -Anadramous fish of the herring family native to the Atlantic coast north from the Carolinas
      -Planktivorous, focusing on larger zooplankton.  
Also eat the larvae of other fish
      -Preyed upon by most larger piscivorous fish
      -A "brittle" species
                -doesn't do well with dramatic temperature changes
                -not easily transported by humans
       
(Bean 2002)  (USGS 2010)  

5. Ecology and Life History (in Land locked Lakes)
    - Generalists.  Highly invasive.  
    - Out-compete other fish and over-feed on macro-                       zooplankton.  
    - Can become a huge part of the diet of larger fish.
    - Don't like the super-cold.  
            - Retreat to deeper water during winter.
            - Move towards shallow waters in April.
            - Spawning peaks in July
Disclaimer: Alewife is a native and culturally valued fish along the Atlantic coast and connected river-ways and there are efforts to restore impaired populations in these areas.
(Bean 2002) (Madenjian et al 2008)
   

6. Introduction and Invasion in Other Lakes
    - First detected in Lake Ontario in  Established in all  Great Lakes by 1954.
    - Modes of Introduction:
          - Natural movement between water bodies 
          - Human stocking
          - Movement through human-built waterways
    - Recorded in Lake St. Catherine in 1997
(Bean 2002) (Good and Cargnelli 2004)

7. (USGS 2010)

8. Good and Cargnelli 2004

9. Alewife in Lake Champlain
  - First observed in 2003
  - Exhibited a population boom and a winter mass die-off in
  - Monitoring and assessment underway 
             - No conclusive alewife impacts on the lake yet
             - No management plan established   
(Vermont Agency of Natural Resources 2008)

10. Findings Case Study - Otsego Lake, NY
Case Study - Otsego Lake, NY
Introduced in 1986, established population
Shallower than Lake Champlain, biologically similar 
                                                                              (Harman, 2006)
In 1990s Otsego Lake exhibited increases in:
Oxygen depletion rates
Chlorophyll a
Phosphorus
Decrease in transparency
Introduced fish species studied since 1930s, lots of pre-alewife data                                                                 
                                                                              (Albright et al., 2002)
Otsego Lake in New York has been studied to determine the effects of alewives on zooplankton populations and top down trophic cascades. Alewives were introduced into Otsego Lake in 1986, so the established population that has been studied (Harman, 2006). Although Otsego Lake is shallower than Lake Champlain, they are biologically similar lakes. In the 1990s Otsego Lake had an increase in oxygen-depletion rates, chlorophyll a levels, and phosphorus while also having a decrease in transparency, which is thought to be caused by introduced fish such as alewife. Research on introduced fish species has been studied in Otsego Lake since the 1930s, so there is a lot of data on the physical and biological conditions of the lake prior to and after alewife introduction (Albright et al., 2002). 

11. Following Introduction
Water turned green with algae
Lack of large algal grazing zooplankton
Large zooplankton population reduced by alewife                                                              
Increased algal blooms increased turbidity
Reduced Secchi depth measurements 
                                                                     
 Post introduction, the lake water turned green from a lack of algal grazing zooplankton in the lake due to large zooplankton populations being reduced by alewife (Harman, 2006). The increase in algal blooms resulting from established alewife populations also increased the turbidity of the water and reduced Secchi depth measurements (Figure 1; Harman, 2006).
(Harman, 2006)
lakechamplaincommittee.org
co.carver.mn.us

12. Secchi disk transparency in Otsego Lake prior to alewife introduction, and post alewife introduction (Harman, 2006).

13. Zooplankton Size Distribution
Introduction changes size distribution
Alewife prey selectively on large zooplankton
Zooplankton size distribution useful indicator of ecological impacts of alewife
                                                                          (Kraft, 2006)
In Otsego Lake ciscoes dominated from
Large bodied zooplankton dominated 
Grazing on algae, low algal biomass
Alewife become more abundant
High transparency, deeper Secchi depth
                                                            
                                                                     (Albright et al., 2002) 
alewives are a small forage fish that selectively prey on large zooplankton. Old studies have shown how alewife impact food webs, but they are not specific to Lake Champlain. Several studies have looked at zooplankton size distribution after alewife establishment which have shown that larger zooplankton populations essentially disappear. Therefore, zooplankton size distribution is a useful variable to study in evaluating the ecological impacts of alewife (Kraft, 2006).
    The population of certain fish species and zooplankton abundances were studied in Otsego Lake. From 1970 to 1988, ciscoes were a dominant fish species in the lake until alewife became more abundant. While cisco dominated the lake, large bodied zooplankton also dominated the zooplankton community. During this time, the abundance of large bodied zooplankton allowed for the grazing of algae, creating low algal biomass in the lake (Albright et al., 2002). This resulted in high transparency and deeper Secchi disk measurements during this time period (Figure 1; Harman, 2006).
hamiltonnature.org

14. Size Distribution Cont.
Post introduction shift in zooplankton community
        Alewife selectively prey on large zooplankton 
Daphnia and Leptodora
        Since 1990s  
Bosmina coregoni
        smaller zooplankton species has dominated Otsego Lake
                                                                    (Albright et al, 2002)
Alewife have top down effect on food web
Establishment -- fewer large cladoceran, especially daphnia
Increased populations of small cladocerans and copepods
Increased algal biomass, lack of large cladocerans consuming large algal particles
                                                                             (Kraft, 2006)
cf.adfg.state.ak.us

15. The composition of the crustacean zooplankton of Crystal Lake (Stafford Springs, Connecticut) before (1942) and after (1964) a population of Alosa aestivalis had become well established. Each square of the histogram indicates that 1 percent of the total sample counted was within that size range. The larger zooplankters are not represented in the histograms because of the relative scarcity of mature specimens. The specimens depicted represent the mean size (length from posterior base lines to the anterior end) of the smallest mature instar. The arrows indicate the position of the smallest mature instar of each dominant species in relation to the histograms. The predaceous rotifer, Asplanchna priodonta, is the only noncrustacean species included; I other rotifers were present but not included in this study.
(Brooks and Dodson, 1965)

16. Landlocked vs. Anadromous Alewife
Both prey on zooplankton
Landlocked, continuous interaction with zooplankton
Keystone species in some E. North American lakes
Dominant in determining structure of zooplankton communities
Lakes with landlocked alewife
Smaller bodied zooplankton
After introduction, rapid decline in zooplankton body size
Constant predation pressure on zooplankton 
Zooplankton size remains small throughout growing season
Changes in zooplankton community drive natural selection of next generation
Eco-evolutionary feedbacks strong
-Landlocked alewives spend entire life in freshwater lakes
-Lakes with landlocked populations consistently have smaller bodied zooplankton populations than lakes without alewives
-introduction of alewife populations into lakes previously lacking alewives causes rapid declines in zooplankton body size
-In landlocked lakes, where predation pressure is continuous, changes in zooplankton communities caused by one alewife generation are likely to carry over to drive strong natural selection on the traits of the next generation
(Palkovacs and Post, 2008)

17. Eco-evolutionary Feedbacks
Strong in landlocked populations
Landlocked alewives become morphologically adapted to foraging on smaller prey
Consume smaller prey/zooplankton 
Shift in body size of zooplankton present after introduction
More pronounced for cladocerans than copepods
(Palkovacs and Post, 2008)
fmel.ifas.ufl.edu

18. (Study in CT lakes with anadromous and landlocked alewife)
-In spring landlocked lakes had smaller zooplankton
-During summer landlocked lakes had significantly larger zooplankton than anadromous lakes
-reason--> average size of zooplankton decreased significantly in anadromous lakes and did not change in landlocked lakes
-summer copepod populations significantly higher in landlocked lakes
**smaller zooplankton to start with in landlocked lakes
(Palkovacs and Post, 2008)

19. Condition prevalent in species that prey upon alewife.
(Lake Trout, Atlantic Salmon)
Lake Champlain: The extent to which alewife contribute to thiamine deficiency in fish species in unknown, however thiamine deficiencies have been recorded in Lake Trout, this is probably true for other species as well.
(Marsden 2010)

20. An enzyme present in certain plant/fish species that splits Thiamine molecules in two.
A vitamin of the B-complex, essential to animals.

21. Family Cyprinidae (Minnows or carps):
Common bream (Abramis brama) Central stoneroller (Campostoma anomalum) Goldfish (Carassius auratus) Common carp (Cyprinus carpio) Emerald shiner (Notropis atherinoides) Spottail shiner (Notropis hudsonius) Rosy red, Fathead minnow (Pimephales promelas) Olive barb (Puntius sarana)
Family Salmonidae (Salmonids):
Lake whitefish (Coregonus clupeaformis) Round whitefish (Prosopium cylindraceum)
Family Catostomidae (Suckers):
White sucker (Catostomus commersonii) Bigmouth buffalo (Ictiobus cyprinellus) 
Family Ictaluridae (North American freshwater catfishes):
Brown bullhead catfish (Ameiurus nebulosus) Channel catfish (Ictalurus punctatus) 
Other families: Bowfin (Amia calva) - family Amiidae (Bowfins) Burbot (Lota lota) - family Lotidae (Hakes and burbots) White bass (Morone chrysops) - family Moronidae (Temperate basses) Rainbow smelt (Osmerus mordax) - family Osmeridae (Smelts) Loach, Weatherfish (Misgurnus sp.) - family Cobitidae (Loaches)

22. Characterized by: -Loss of Equilibrium -Lethargy -Hemorrhaging
-Hyperexcitability
-Ultimately, death.

23. -Effects of EMS found in Atlantic Salmon, Steelhead Trout, and Lake Trout in the Great Lakes. (Mandenjian, 2008)
“The proliferation of alewives in the late 1870’s appears to have been the keystone change in the great lakes ecosystem that pushed the Atlantic Salmon population to extirpation via EMS reducing fry survival and perhaps also via anorexia, induced by thiamine deficiency, causing starvation of adults.” (Ketola et al., 2000)

24. Heavily Impacted Fish Species
*NOT AT ALL TO "SCALE"*
pond.dnr.cornell.edu

25. Atlantic Salmon
Early life stages of atlantic salmon are not at risk of predation by alewife because they do not overlap spatially.
Atlantic salmon spawn in up-stream reaches where they spend up to two years.  (Ketola,2000)
Threat to Atlantic Salmon is mainly Early Mortality Syndrome
Lag time in negative effects on salmon populations
EMS chokes recruitment rates (Madenjian, 2008)
Lake Ontario Example
Strong correlation between alewife invasion and atlantic salmon extirpation. (Madenjian, 2008)

26. Lake Trout
The early life history of lake trout allows larvae to be vulnerable to predation by alewife.
Spatial Overlap!
Pelagic lake trout eggs typically hatch during April and May           (Madenjian, 2008)
Tank experiments have shown that the predator avoidance response shown by lake trout larvae is to flee upward in the water column 
Creates spatial overlap and leaves lake trout larvae very susceptible to predation by alewives                                                  (Strakosh and Krueger 2005)
sciencenews.org

27. Lake Trout
Several other compounding factors which contribute to Lake Trout population declines
Overfishing
Predation by sea lamprey
EMS
Important to differentiate between lake trout population declines induced by different factors.
Which declines are more heavily alewife related?
sportfishingamericas.files.wordpress.com

28. Lake Trout
Lake trout stocks collapsed in all five Laurentian Great Lakes by 1960, primarily through overfishing and predation by sea lampreys. (Hansen, 1999)
Regardless of lake trout stocking programs begun in the 1960s and 1970s, only lake trout populations in Lake Superior have recovered.
   **highly correlated with a very low abundance of alewife**                                             (Madenjian, 2008)
Remember: Even with successful recruitment, lake trout face a double threat from alewife - EMS and predation

29. Emerald Shiner
Due to its physical and ecological similarity to alewife, it is particularly at risk to alewife invasions.
OVERLAP!
Alewife interfere with emerald shiner reproduction by feeding on pelagic eggs and fry
Peak hatching of emerald shiner eggs occurs in June and July
Eggs and larvae are pelagic, and newly hatched larvae have been observed primarily in shallow water  (Madenjian, 2008)
This life cycle overlaps spatially and chronologically with alewife reproductive cycles and puts the emerald shiner at high risk of predation.

30. Emerald Shiner in the Great Lakes
Studies in the great lakes have shown a high correlation between alewife population increases and emerald shiner population crashes.
Studies in Lakes Michigan and Huron have shown that Emerald Shiner populations were greatly reduced during the early 1960s
Coincident with the increased abundance of alewives in both lakes                                                                  (Madenjian, 2008)
The emerald shiner population collapse in Lake Michigan spread from the northern part of the lake southward
Spatially coincident with the spread of alewives into the lake                                                                     (Wells, 1977)
Emerald shiner populations in Lakes Michigan, Huron, and Ontario have not recovered since 1960
Largely due to a lack in alewife population declines (Wells, 1977)

31. These aren't the only impacted fish species....
Slimy sculpin
Lake whitefish
Cisco
Bloater
Rainbow smelt
Atlantic salmon
Lake trout
Emerald shiner
Yellow perch
Deepwater sculpin
Strongest 
Effect
Minimal Effect
Chart Recreated from Madenjian, 2008
image: csulb.edu

32. Social Implications Die-offs reek and are unsightly
Lost cultural heritage attached to native fish being displaced
Reduced recreation/use of lake with more die-offs
May increase algal blooms
bobberbobsfishen.com

33. Economic Implications
Reduced lake trout and salmon viability makes for bad fishing.
Tourism hurts: mass die-offs, fishing, stigma of having a non-pristine lake dominated by invasives
Algal blooms lead to decreased use of lake for many activities
bizbox.slate.com/blog/dollar-sign.jpg

34. Ecological Implications ...a take home message
Prey fish species are largely displaced 
Shifting trophic interactions
Larger zooplankton are selectively preyed upon
Small zooplankton and phytoplankton proliferate.
Large fish subject to EMS      are less viable
Die-offs don't seem to have major ecological impacts.

35. Assessment Endpoints Secchi depth measuring turbidity
Zooplankton species populations
Phytoplankton species populations/abundance
Population of at-risk fish species
Salmonid egg hatching success (EMS effects)
Direct testing for thiamine deficiency in salmonids
Lecia
seagrant.wisc.edu

36. Recommendations Action- Preventative Measures-
Increase stocking of lake trout and atlantic salmon following die-offs 
Increase monitoring
zooplankton size distribution and populations
More research on diet of alewife and ecological niche in Lake Champlain
Assess effectiveness of monitoring
Preventative Measures-
Strict measures restricting transportation of alewife in-state are already in place.
... or dead ones.

37. Literature Cited
Albright., M.F., Harman, W.N, & Warner, D.M. (2002). Trophic changes in Otsego Lake, NY following the introduction of the alewife (Alosa psuedoharengus). Lake and Reservoir Management, 18(3),
Bean, Tim. (2002) “Introduced Species Summary Project: Alewife: /Alosa pseudoherengus/.” Retrieved from
Brooks, J. L. & Dodson, S. I. (1965). Predation, body size, and composition of plankton. Science, 150,
Flittner, G. A. (1964). Morphometry and life history of the emerald shiner, Notropis atherinoides Rafinesque. Doctoral dissertation.University of Michigan, Ann Arbor.Hansen, M. J. (1999). Lake trout in the Great Lakes: basin wide stock collapse and binational restoration. Michigan State University Press
Good, S and Cargnelli, L. (2004) "Alternative Strategies for the Management of Non-Indigenous Alewives in Lake St. Catherine, Vermont." Retrieved from _http:// Reports_and_Documents/Fish_and_Wildlife/Alewife_Final_Report_-_April_2004.pdf_.
Ketola, G. H., Bowser, P.R., Wooster, G.A., Wedge, L.R., & Hurst, S.S. (2000). Effects of thiamine on reproduction of Atlantic salmon and a new hypothesis for their extirpation in Lake Ontario. 
 Transactions of the American Fisheries Society, 129:607–612.
Lake Champlain Alewife Impacts – February 2006 Workshop Summary (3 Speakers)
  Harman, W. N. (2006, February). Trophic Changes Following the Introduction of the Alewife in Otsego Lake, NY. Lecture presented at Burlington, VT.
   Kraft, C. E. (2006, February). Food Web Effects and Population Dynamics of Alewives, Lecture presented at Burlington, VT.
Madenjian, C.P. (2008). Adverses Effects of Alewives on Laurentian Great Lakes Fish Communities. North American Journal of Fisheries Management, 28(1):
Palkovacs, E.P., and Post, D.M. (2008). Eco-evolutionary interactions between predators and prey: can predator-induced changes to prey communities feed back to shape predtor foraging traits? Evolutionary Ecology Research, 10:

38. Post, D. M. , Palkovacs, E. G. , Schielke, E. G. , & Dodson, S. I
Post, D.M., Palkovacs, E.G., Schielke, E.G., & Dodson, S.I. (2008). Intraspecific phenotypic variation in a predator affects zooplankton community structure and cascading trophic interactions. Ecology, 89:
Strakosh, T. R., and Krueger, C.C. (2005). Behavior of postemergent lake trout fry in the presence of the alewife, a nonnative predator. Journal of Great Lakes Research, 31:296–305.
USGS. (2010). “Non-Indigenous Aquatic Species.” Retrieved from speciesmap.aspx?SpeciesID=490.
Vermont Agency of Natural Resources. (2008). "Lake Champlain Sees Its First Alewife Die-Off." Retrieved from _http://
Wells, L. (1977). Changes in yellow perch (Perca flavescens) populations of Lake Michigan, 1954–75.Journal of the Fisheries Research Board of Canada, 34: