Effectiveness of a refuge for lake trout in western Lake Superior I: Empirical analysis of past performance

North American Journal of Fisheries Management
By: , and 

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Abstract

The Gull Island Shoal Refuge was created in 1976 in response to overfishing of the Lake Trout Salvelinus namaycush population in the Apostle Islands region of western Lake Superior. Our objective was to evaluate effectiveness of the refuge by determining whether Lake Trout abundance, growth, maturity, and mortality differed inside and outside the refuge. We compared abundance of wild and stocked fish captured inside and outside the refuge during spring large-mesh gill-net and summer graded-mesh gill-net surveys. We compared growth and mortality during four periods corresponding to four generations of wild Lake Trout, including the last generation that hatched before the refuge was instituted (sampled in 1981–1984) and three generations that were protected by the refuge (sampled in 1985–1992, 1993–2000, and 2001–2010). Maturity of wild fish inside and outside the refuge was compared only for the latter period (2001–2010) because maturity was not assessed earlier. After the refuge was created, wild Lake Trout abundance increased and stocked Lake Trout abundance decreased. Wild adults and juveniles were more abundant inside than outside the refuge, and stocked adults were less abundant inside than outside the refuge. Growth of wild fish did not differ inside versus outside the refuge before 2001, but wild fish grew faster to a shorter asymptotic length inside than outside the refuge during 2001–2010. Wild fish matured at a similar length but an older age inside than outside the refuge during 2001–2010. Survival of wild fish did not differ inside versus outside the refuge before 1993, but mortality was lower inside than outside the refuge during later periods (1993–2000 and 2001–2010). We conclude that the Gull Island Shoal Refuge enhanced the population growth of wild Lake Trout in the Apostle Islands region and should be retained in the future to sustain conditions that favor population growth.

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Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Effectiveness of a refuge for lake trout in western Lake Superior I: Empirical analysis of past performance
Series title North American Journal of Fisheries Management
DOI 10.1080/02755947.2015.1074959
Volume 35
Issue 5
Year Published 2015
Language English
Publisher American Fisheries Society
Contributing office(s) Great Lakes Science Center
Description 15 p.
First page 988
Last page 1002
Time Range Start 1981-01-01
Time Range End 2010-12-31
Country United States
State Wisconsin
Other Geospatial Lake Superior
Online Only (Y/N) N
Additional Online Files (Y/N) N
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