**The title, authors, and abstract for this completion
report are provided below. For a copy of the completion report, please
contact the GLFC via e-mail
or via telephone at 734-662-3209**
Coordination
Workshops Concerning Early Mortality of Lake Trout in the Great Lakes
June 2010
2 Quantitative
Fisheries Center, Michigan State University, 153 Giltner
Hall, East Lansing, MI 48824
3 Alpena Fisheries Research Station, Michigan Department of Natural Resources and Environment
160 E. Fletcher St. Alpena, MI
49707
ABSTRACT:
Two workshops were convened
that brought together fishery researchers and biologists from across the Great Lakes
basin to discuss the current state of knowledge regarding early mortality of
lake trout and how low survival rates in some lakes may be impeding the
transition to self sustaining populations. The first workshop was held in October
2008 and consisted of a total of 22 presentations that summarized current
understanding of lake trout ecology and population dynamics across the lakes.
In addition, a discussion session was held for the purpose of synthesizing
presented information and to propose answers, new ideas, or new questions
regarding early mortality of lake trout and how it is influencing lake trout
populations in the Great Lakes. Through this discussion session, it became apparent
that providing answers as to what factors were causing low survival rates would
be difficult given the wide-spread environmental changes that most of the lakes
have undergone; as well, it would be difficult to evaluate stocking or
management strategies for increasing survival of early life stages of lake
trout as it is not clear how relevant previous research findings are given the
environmental changes that have occurred. The consensus among the participants
of the first workshop was that it would be advantageous if the second workshop was
devoted primarily to brainstorming and discussing possible research projects to
answer lingering questions regarding differences in survivability and ecology
of both stocked and wild lake trout. The second workshop was held in April 2010
and, as requested, was devoted to brainstorming and discussing potential
research areas. The five areas of research that were primarily discussed by
participants of the second workshop were to: 1) conduct across-lake comparison
of differences in survival of stocked fry, fingerlings, and yearling, 2) assess
behavior and mortality of lake trout immediately after stocking, 3) evaluate
how modifications to rearing environments might increase survival rates of
stocked fish, 4) compare diets of wild and hatchery lake trout diets and
physiological differences between wild and hatchery fish that might be
influencing their feeding (e.g., gillraker spacing),
5) conduct hatchery-based evaluations of lethality limits of early life stages
of lake trout and of bioenergetic model inputs.