**ABSTRACT NOT FOR CITATION WITHOUT AUTHOR PERMISSION. The title, authors, and abstract for this completion report are provided below. For a copy of the full completion report, please contact the author via e-mail at brenden@anr.msu.edu. Questions? Contact the GLFC via email at stp@glfc.org or via telephone at 734-662-3209.**
Coordination Workshops Concerning Early
Mortality of Lake Trout in the Great Lakes
Travis O. Brenden1, Ji X. He2
1 Quantitative
Fisheries Center, Michigan State University, 153 Giltner
Hall, East Lansing, MI 48824
2 Alpena Fisheries Research Station, Michigan Department of Natural
Resources and Environment, 160 E. Fletcher St., Alpena, MI 49707
June 2010
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.