Yellow perch in Lake Michigan: investigating size-selective mortality and alternative estimators of age
Dub, Joshua
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https://hdl.handle.net/2142/46662
Description
Title
Yellow perch in Lake Michigan: investigating size-selective mortality and alternative estimators of age
Author(s)
Dub, Joshua
Issue Date
2014-01-16T17:58:03Z
Director of Research (if dissertation) or Advisor (if thesis)
Czesny, Sergiusz J.
Wahl, David H.
Department of Study
Natural Resources and Environmental Sciences
Discipline
Natural Resources and Environmental Sciences
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
M.S.
Degree Level
Thesis
Keyword(s)
Yellow perch
Lake Michigan
age
size-selective mortality
Abstract
Understanding the recruitment dynamic of fishes is a critical component of fisheries research and management. However, the interplay of both biotic (i.e. spawning stock biomass and predation) and abiotic (i.e. water temperature and currents) factors throughout pre-recruit life stages makes recruitment predictions challenging. A combination of multiple variables is likely responsible for year-class strength and the prevalence of any individual factor may vary from year to year. Within Lake Michigan, yellow perch, Perca flavescens, have experienced widespread recruitment failure persisting from the early 1990s to the present. As one on the most sought after recreationally and commercially valuable native species within Lake Michigan, exhaustive research has attempted to identify the timing and factors influencing recruitment variability of yellow perch. Difficulties sampling and ageing juvenile fishes have largely limited these investigations to the larval and adult life stages, while the juvenile life stage has been understudied. To improve our knowledge of yellow perch early life history dynamics and accuracy of age estimates, I performed two separate studies. First, I examined size variability and size-selective mortality during the juvenile life stage of yellow perch in southwestern Lake Michigan. Second, I assessed the utility of sagittal otolith weight as a rapid and objective predictor of yellow perch age using random forest analysis. My investigation provided significant evidence of size-selective mortality beyond the first year of life and size-specific growth during the first year, overwinter period. Sagittal otolith weight provided accurate estimates of yellow perch age, although the utility of these estimates diminished as age increased. My results suggest that size-selective mortality may influence the size-structure, number of recruits, and therefore year-class strength of yellow perch in Lake Michigan. Additionally, age estimates from otolith weight represent a rapid and objective alternative to traditional methods and may provide substantial resource savings. Further research is required to assess the population level influences of size-selective mortality in Lake Michigan while the utility of otolith weight as a predictor of age is likely species and system specific and should be investigated on an individual basis prior to implementation.
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