Thermal Benchmark Development for Round and Lake Whitefish Based on Lab Incubation Studies

There is a need to further refine thermal effect endpoints for fish species such as round and lake whitefish.  Establishment of thermal preferences, tolerances and regimes will permit accurate risk assessment evaluations by life stage for these species. The objective of the study was to develop updated thermal preferences and tolerances for round and lake whitefish eggs. Earlier studies on developing thermal tolerances for round whitefish are over 30 years old, and were not conducted with ambient lake temperatures. Present studies were conducted in a hatchery specially design for thermal inputs which were computer controlled.  Egg incubation studies focused on the temperature effects on embryo development for both species. Results will be presented on survival at various stages of development including hatch under each temperature regime. Temperature units will be calculated for each species when subjected to thermal inputs. Preliminary data suggests high survival, even for embryos incubated under maximum temperature changes.