Climate and dynamics of walleye (Sander vitreus, formerly Stizostedion vitreum vitreum) populations in North America.
Published: 2005
Language: eng
Number of pages: 197
Description: Climatic conditions significantly influenced growth of walleye in North America. Genetically distinct walleye populations appear to have developed their own adaptation strategies to respond to their regional climatic conditions. Walleye early growth rate showed a significant latitudinal trend: the populations at low latitudes, experiencing high thermal input, had a high early growth rate (o) and a high value for k, the rate of approaching asymptotic length (Linfinity) as defined in the von Bertalanffy growth model. However, the impact of climatic conditions on walleye growth in later life, as characterized by L infinity was not significant.In Lake Erie, three walleye sub-populations (i.e. the western basin, Van Buren Bay, and Grand River) showed distinct demographic characteristics. The western basin walleye had a lower early growth rate than the eastern basin walleye. The differences in early growth rate among these walleye subpopulations were associated with the differences in thermal regimes experienced by each sub-population during the growing season. The overheated western basin provided the worst growth habitat for walleye during summer/fall. Younger fish cannot avoid these overheated conditions and thus may be exhibiting reduced growth rates because of the unsuitable growth habitat in the western basin. The survival rates of adult walleye in the eastern basin were higher than the lakewide average, but the abundance was less than one percent of the lakewide adult walleye abundance. The warmer and clearer water conditions in 1998 created more walleye habitat than in 1993. The increases in water temperature and decreases in water level that may result from climate change will have different impacts on the habitat suitable for walleye among the three basins, with the greatest effect in the western basin. A simulation study showed that density-dependent early survival and density-dependent adult growth and egg production significantly affect the dynamics of the walleye metapopulation in Lake Erie. Walleye early survival (i.e. recruitment) could be a bottleneck, setting the overall sizes of the western basin and eastern basin sub-populations. This bottleneck would be sensitive to the changes in habitat expected from climate change.
Notes: Source: Dissertation Abstracts International, Volume: 66-10, Section: B, page: 5205.

Thesis (Ph.D.)--University of Toronto, 2005.

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