Developing Life-History Based Population Dynamics Models for Great Lakes Fishes

Since 1997 we have been exploring the use of mechanistic models to link changes in habitat conditions with the population dynamics of important fish species. Our initial work in this area was supported by a GLFC research grant held jointly with Dr. Dan Hayes (MSU) and Dr. Nigel Lester (Ontario Ministry of Natural Resources). Collectively we developed habitat supply - population dynamics models for Lake Erie walleye, yellow perch and smallmouth bass, Au Sable River steelhead, and Lake Superior lake trout. More recently we initiated a project funded by the US FWS Restoration Act to use a similar approach for Lake Superior cisco. We have also used the Lake Erie walleye model to explore the potential effects of climate change on Great Lakes fisheries.  More details on the lake trout and cisco modeling efforts, both carried out by Jones lab students, are provided below.



Students involved:
Lake trout in Lake Superior (John Netto, MS)

We developed a habitat supply model for Lake Superior "lean" lake trout populations along the shore of Minnesota, and have used the model to examine the relationship between habitat supply and lake trout population dynamics in Lake Superior. By looking at habitat needs for specific life stages of lake trout, we are able to describe the effects of habitat supply and the mechanisms by which changes in habitat supply might drive lake trout population dynamics in Lake Superior. Although it is common to associate general categories of habitat with certain species (i.e. cold, deep lakes for lake trout), the habitat requirements of a fish species are very different at each life stage in the a fish's life history.  In developing the lake trout model, we let the habitat requirements at each lifestage determine how we model survival and growth for that lifestage.  Our model results suggested that variation along Lake Superior's Minnesota shoreline in spawning habitat quality may explain spatial differences in the success of lake trout restoration in this region.		 Collaborators:
Cisco in Lake Superior (Jared Myers, MS)

Many factors may affect the population dynamics of cisco, a species that exhibits extreme variations in year-class-strength in Lake Superior. These include but are not limited to: predation and competition, particularly with non-native species; environmental factors; commercial exploitation; and disease. A combination of these factors, functioning at different life stages, likely determine the size of a cohort. We will be using publsihed information on these factors as well as expert opinion to develop a simulation model that will provide a basis for understanding the mechanistic links to growth and survival between life stages. The model will track individual cohorts in a population from eggs to spawning stock. Modeling individual year classes will help  to identify and evaluate the relative importance of mortality between life stages. Of particular interest is the influence of hypothesized factors affecting the life stages between egg deposition and age-1 survival, because it is believed that this period of development determines year class strength. Where data and information are lacking, the model will help reveal the importance of particular sources of uncertainty through sensitivity and uncertainty analysis.

Funding partners:

Reports and publications:
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