Efforts to rehabilitate lake trout in the upper Great Lakes have met with limited success. One key factor hypothesized to impede progress towards rehabilitation is inadequate age-0 survival (from egg deposition to age-1). We evaluated age-0 survival rates for lean lake trout populations in the Michigan waters of Lake Superior during three periods of significantly different abundance levels and mortality regimes: pre-sea lamprey (1929–1950), sea lamprey-dominant (1951–1962), and current (1988–1993). Current age-0 survival rate was calculated to be 0.00118 which is lower than age-0 survival rates corresponding to the pre-sea lamprey (0.00372) and sea lamprey-dominant (0.00416) periods. Population growth rates of lake trout were found to be extremely sensitive to changes in age-0 survival rates. We found that if the current lake trout population in the Michigan waters of Lake Superior exhibited an age-0 survival rate similar to that of the pre-sea lamprey population, the current population would be increasing in numbers rather than decreasing. As increasing age-0 survival will greatly increase the population growth rate and facilitate the rehabilitation process, we recommend that future research and management efforts place a high priority on evaluating the factors that are currently depressing survival rates of age-0 lake trout in Lake Superior in order to develop strategies to overcome these impediments.
All Science Journal Classification (ASJC) codes
- Ecology, Evolution, Behavior and Systematics
- Aquatic Science