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Fecundity Changes in Two Exploited Walleye Populations

1988; Wiley; Volume: 8; Issue: 2 Linguagem: Inglês

10.1577/1548-8675(1988)008 2.3.co;2

1548-8675

Dominic A. Baccante, David M. Reid,

Aquatic Invertebrate Ecology and Behavior

Fish in Henderson and Savanne lakes, boreal lakes located near Thunder Bay, Ontario, were experimentally exploited for 6 years by different harvest strategies. The adult population of walleyes Stizostedion vitreum in Henderson Lake, estimated from trap nets, was drastically reduced over a period of 3 years, from 1,336 to 375 fish; exploitation rates ranged from 25 to 65%. In Savanne Lake, intermediate-size walleye (25–54 cm total length) were harvested for 5 years; yield was slightly less than the average adult production. The walleye population was reduced from 5,595 to 4,206 fish by exploitation rates of 12–16%. Both populations have shown statistically significant annual increases in fecundity since the start of exploitation. Yearly fluctuations in fecundity, especially of older fish, were noted in both lakes; high values occurred in even-numbered years and low values in odd-numbered years. We hypothesize that these fecundity changes reflect food availability, particularly alternate-year fluctuations in the abundance of adult mayflies Hexagenia limbata.