Effectiveness of the Gull Island Refuge for Lake Trout in Lake Superior
File(s)
Date
2014-12Author
Johnson, Melissa J.
Publisher
University of Wisconsin-Stevens Point, College of Natural Resources
Metadata
Show full item recordAbstract
The Gull Island refuge was created in 1976 in response to overfishing of the lake trout population in the Apostle Islands. My objective was to determine if lake trout abundance, growth, maturity, and mortality differed inside and outside the refuge, before and after the refuge was created. To address my objective, I compared abundance, growth, maturity, and mortality between lake trout captured inside and outside the refuge during spring large-mesh and summer graded-mesh gill-net surveys. Wild adult lake
trout abundance increased significantly while stocked adult lake trout abundance
decreased significantly after the refuge was created . Wild adult and juvenile lake trout
were significantly more abundant in side than outside the refuge and stocked adult lake
trout were less abundant inside than outside the refuge. Lake trout grew faster to a shorter asymptotic length inside the refuge than outside the refuge. Lake trout matured at an older age inside the refuge than outside the refuge. Lake trout suffered significantly lower mortality inside the refuge than outside the refuge. I conclude that the Gull Island refuge enhanced wild lake trout population growth in the Apostle Islands region and should be retained in the future to sustain conditions that favor population growth.