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Changes in growth and maturity of walleyes associated with stock rehabilitation in western Lake Erie, 1964-1983

North American Journal of Fisheries Management

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Abstract

The precipitous decline in abundance of walleyes (Stizostedion vitreum vitreum) in western Lake Erie during the 1960s caused major concerns for the future of this resource. Mercury contamination in walleyes in 1970 resulted in a moratorium on commercial fishing in United States and Canadian waters. The opportunity arose for resource agencies to develop a plan for rehabilitation of the walleye stocks, and quota management for walleyes was begun in 1976. After 8 years, the resource had recovered dramatically and the estimated standing stock in 1983 was more than three times that in 1976. In the mid-1970s, however, certain detrimental changes suggested that self-regulatory mechanisms were occurring. The growth rate declined gradually but rather consistently. Growth changes were most evident for young-of-the-year (YOY), yearlings, and 2-year-old fish, which usually constituted more than 80% of the standing stock in 1976-1983. Average lengths of YOY fish decreased by nearly 50 mm (from about 240 mm in 1961 to 190 mm in 1983). Average lengths and weights of yearling and older fish began to decline after 1975 and decreased markedly after 1980. Historically, growth of walleyes in western Lake Erie exceeded that reported for many walleye populations in other waters. Another sign of self-regulation was an increasing delay in the onset of maturity. Most (usually more than 90%) of the yearling males were sexually mature each fall before 1979, but this percentage decreased to only 32 by fall 1983. Usually 80% or more of the age-II females were mature each fall during the 1960s and early 1970s, but this percentage decreased rapidly to only 7 by fall 1983. Prey fish populations declined somewhat in the early 1980s, and their ability to sustain the high abundance of walleyes is a great concern to resource managers.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Changes in growth and maturity of walleyes associated with stock rehabilitation in western Lake Erie, 1964-1983
Series title:
North American Journal of Fisheries Management
Volume
6
Issue:
2
Year Published:
1986
Language:
English
Contributing office(s):
Great Lakes Science Center
Description:
p. 168-175
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
North American Journal of Fisheries Management
First page:
168
Last page:
175
Number of Pages:
7