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Age truncation of alewife in Lake Michigan

Journal of Great Lakes Research
By: , , , and 
https://doi.org/10.1016/j.jglr.2019.06.006

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Abstract

Empirical evidence has shown increased variability in harvest and recruitment of exploited fish populations, which can result directly from exploitation or indirectly from interactions between external drivers and the internal dynamics of age-structured populations. We investigated whether predation in a freshwater system could affect a prey fish population, in the same way fishing affects targeted populations. Using fishery-independent trawl survey data and a suite of quantitative indicators, we evaluated changes in the alewife population in Lake Michigan. Our results provide evidence for a reduction in the mean spawner age, a reduction in the diversity of age classes and the distribution of biomass across them, and increased variability in the proportion of first time spawners in the spawning stock. We used wavelet analysis and estimates of lifetime egg production to demonstrate how the alewife population displays behaviors of instability as the overall biomass declines. Our results provide evidence that predation pressure can influence prey fish populations in a similar manner to fishing on harvested populations, and that conservation of a broad reproducing age structure is likely to be important for buffering against adverse environmental fluctuations and for sustainable management of fish populations.

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Publication type Article
Publication Subtype Journal Article
Title Age truncation of alewife in Lake Michigan
Series title Journal of Great Lakes Research
DOI 10.1016/j.jglr.2019.06.006
Volume 45
Issue 5
Year Published 2019
Language English
Publisher Elsevier
Contributing office(s) Coop Res Unit Atlanta, Great Lakes Science Center
Description 11 p.
First page 958
Last page 968
Country United States
Other Geospatial Lake Michigan
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