Tyler J. Winter

Advanced Composition

Section 1




Proposal for: Population Dynamics and Competition of Lake Herring, Bloaters, and Kiyi in Lake Superior - Mechanisms of Community Structure




I propose to write an UROP proposal to investigate the populations, diets, and interactions between the three dominant planktivores of the western arm of Lake Superior.




Historically, Lake Superior has supported several commercially important fish including lake trout (Salvelinus namaycush), white fish (Coregonus clupeaformis), and lake herring (Coregonus artedi).  Over time exotic species and mismanagement has had a devastating impact on the fish community.  Sea lamprey (Petromyzon marinus) invaded the Great Lakes in 1938 and preyed on large lake trout.  Rainbow smelt (Osmerus mordax mordax) dominated the forage base from 1950 to 1981 and replaced lake herring as the principle forage of lake trout (Lake Superior Committee 2003).  Over-fishing was responsible for the decline in lake herring in the 1960’s (Selgeby 1982); after their decline bloaters (C. hoyi) and kiyi (C. kiyi) became commercially important. 

Today the abundance of smelt and lamprey has been reduced by 90% (Bronte et al. 2003, Lake Superior Committee 2000).  Before smelt invaded Lake Superior the primary planktivores were lake herring, bloaters, kiyi, and short jaw cisco (C. zenithicus) respectively.  The reduction in smelt has allowed native planktivores to recover.  Lake herring suffered poor recruitment even after smelt biomass declined; they have produced only five significant year classes in 22 years (Bronte et al. 2003).  Herring biomass decreased 80% between 1990 and 1998 (Hoff and Bronte 1998).  Today the pelagic fish community is dominated by bloaters and siscowet lake trout (Salvelinus namaycush siscowet). 




Lake herring, bloaters, and kiyi all have similar life histories, diets, and distributions.  The goal of this project is to document the abundance, distribution, age, growth rate, diet, consumption rate, and prey selectivity for each species.  This information will allow us to determine if these species are competing for limited resources and if any of them have a competitive advantage.  Understanding the interactions between these fish enables us to better understand, manage, and predict changes in Lakes Superior’s fish communities.






Fish collections will be made aboard the “Kiyi”, which sails from Ashland, WI, and the “Blue Heron” which sails from Duluth, MN.  These ships are equipped with trawl nets and acoustic sampling equipment that will be used to count and collect fish.  Fish and plankton sampling will take place in transects along the south shore of Lake Superior between Duluth, MN and Houghton, MI.  All herring, bloaters, and kiyi that are collected will be weighed and measured.  Scales, otoliths, and stomachs will be collected from at least 30 fish from each segment of each transect.  Scales and otoliths will be used to determine the fish’s age and growth rate.  Age and growth data will be compiled to determine the annual mortality and production for each species.  Stomach contents will be identified counted and weighed to determine the consumption rate for each species.  Stomach contents will be compared to plankton samples to determine prey preferences for each species; these will then be compared between species to determine the amount of competitive interaction.  Consumption rates will be used to estimate the amount of prey each species consumes daily.  The final analysis will include all the data and will determine the effect that each species has on the others and on its environment.         




The natural communities of the Great Lakes have been highly impacted by human activity, both intentional and unintentional.  If we intend to preserve, maintain, and utilize these expansive resources we must understand them better.  Precisely, we are interested in the mechanisms that control community structure, population dynamics, and competition.  These mechanisms have been determining the rise and fall of species since the origins of life.  This is a unique and important opportunity to learn about the Great Lakes and the food webs within them.  Studies like this have the potential to show us how to protect native fish and repair our damaged ecosystems.  I hereby seek permission to initiate this investigation.




Write Proposal

March 2005

Collect and count fish

August 2005

Ages, growth, and mortality rates

September 2005

Gut analysis, consumption, and selectivity

October 2005

Diet overlap/ competition

November 2005

Write report

December 2005/ January 2006









As an undergraduate, I have made it my goal to obtain as much experience in the fields of ecology, ichthyology, and fisheries management as possible.  To that end I have successfully completed a research project “Population size, growth, and control of exotic goldfish (Crassius atratus) in a small impoundment:  implications for managing future invasions”.  In the course of completing that project I learned a great deal about both fish populations and the effort it takes to study them.  For over a year I have been employed by the Natural Resources Research Institute.  During that time I have learned to identify many of the macro-invertebrates that I may encounter in the course of this project.  My employment at NRRI has also taken me onto both lakes Huron and Superior to sample fish.  During my undergraduate career I have been continuously employed in the Biology Department Stock Room at the University of Minnesota, Duluth.  My time at the stock room has further demonstrated to me the importance of consistency and focus in the biology field.  I have also had classroom experience in related fields, such as geological limnology, entomology, lake ecology, plankton biology and ichthyology.  In the future I plan on pursuing a master’s degree in fisheries ecology and then a Ph.D. in a related field. 




Bronte, C. R. and M. P. Ebener, D. R. Schreiner, D. S. DeVault, M. M. Petzold, D. A. Jensen, C. Richards, S. J. Lozano (2003) Fish community change in Lake Superior,1970–2000. NRC Research Press Website. http://cjfas.nrc.ca


Hoff, M. H. and C. R. Bronte.  (1998) Population status and trends for economically and

ecologically important fishes in Lake Superior, 1978-97.  Minutes of the Lake Superior

Committee Meeting, March 17-18, 1998, Great Lakes Fishery Commission.


Horns, W.H., C.R. Bronte, T.R. Busiahn, M.P. Ebener, R.L. Eshenroder, T. Gorenflo, N. Kmiecik, W. Mattes, J.W. Peck, M. Petzold, D.R. Schreiner. (2003) Fish-community objectives for Lake Superior. Great Lakes Fish. Comm. Spec. Pub. 03-01. 78 p.


Selgeby, J. H. (1982) Decline of lake herring (Coregonus artedii) in Lake Superior: an analysis of the Wisconsin herring fishery, 1936–78. Can J Fish Aquat Sci 39:554–63.



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