Science Advisory Report 2008/042
Recovery Potential Assessment of Great Lakes and St. Lawrence River watersheds (Designatable Unit 8) Lake Sturgeon (Acipenser fulvescens) population
Summary
- Lake sturgeon remain widespread throughout the Great Lakes and St. Lawrence River basin (Designatable Unit 8), but serious declines in the number and size of populations have occurred.
- A recovery target of 1188 spawning females per year was developed for 12 Sturgeon Management Units around the basin that were either genetically distinct or geographically isolated.
- Model projections suggest that recovery without intervention is possible over 170 - 300 years under the currently estimated suite of mortality rates and life history parameters.
- Based on the recovery target and assuming that current abundances are 10% of this target, the time to 95% probability of recovery range from 20 years to over 100 years (1-3 generations), depending on the recovery actions implemented.
- The presence of dams and exploitation, were the most important lake sturgeon threats in Designatable Unit 8.
- Dams result in habitat fragmentation, flow manipulation, habitat loss, and limit access to spawning habitat.
- Exploitation (commercial fishing, First Nation harvest, and poaching) impacts survival of sturgeon and changes the time to reach recovery.
- Early adult survival is the vital rate most sensitive to perturbations for DU8 lake sturgeon.
- Maximum proportional increases in population growth rates, however, can be achieved by focusing recovery efforts on age-0 and juvenile survival.
- While adult habitat is not believed to be limiting, there is much uncertainty around whether spawning habitat is limiting in some of the Sturgeon Management Units.
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