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Lake-wide mark and recapture investigation of Lake Michigan yellow perch: evaluation of interstate movements, spawning site fidelity, spawning population abundance, and sources of mortality
David C. Glover1, John M. Dettmers2, and David F. Clapp3
1 Department of Natural Resources and Environmental Sciences, University of Illinois and Center for Aquatic Ecology, Illinois Natural History Survey
2 Lake Michigan Biological Station, Illinois Natural History Survey
3 Charlevoix Fisheries Research Station, Michigan Department of Natural Resources
In Lake Michigan, yellow perch Perca flavescens have suffered from poor recruitment since 1989. Until mechanisms affecting recruitment are identified, it is essential to properly manage the existing adult population. Delineation of yellow perch stocks has proven difficult to achieve but is an integral element for successful management of this species. To evaluate the stock structure of yellow perch in the southern basin of Lake Michigan and Green Bay, we used recaptures and recoveries from a lake wide mark-recapture study implemented from 1996-2001. Yellow perch exhibited directional preference toward or within rocky substrate during summer (June – August) and non-summer months, increasing in magnitude for the later period. Movement was generally random where rocky substrate was lacking. Ninety percent dispersal distances ranged from 12.8 to 101.4 km during summer, resulting in overlap among yellow perch in the southern basin (particularly between adjacent states) as well as movement across state boundaries. Because dispersal distances overlap current management boundaries, managers should carefully consider the delineation of biologically significant management boundaries to incorporate the range and patterns of yellow perch movements. Spawning site fidelity was highly variable, ranging from 35 to 80.0%. Results from Illinois suggest fidelity is directed toward larger areas rather than specific sites, indicating that large spawning complexes exist. Despite strong fidelity in some areas, straying was evident from all sites during the spawning season, resulting in mixing throughout the entire southern basin, which could promote gene flow. Differences in growth rates observed for fish released from Michigan, however, indicate that the population is not completely panmictic and may display differences in characteristics that justify treating certain portions of the population separately in terms of management.
We also evaluated whether survival was similar or different among the four states within the southern basin of Lake Michigan (i.e., Wisconsin, Illinois, Indiana, and Michigan) and determined movement rates across jurisdictional boundaries using mark-recapture models. Using the most complete data set available within Illinois, we evaluated survival and movement rates on a much smaller scale. We also examined survival of yellow perch in Green Bay through time and determined the utility of mark recapture as an estimator of abundance for this region. The Green Bay, Lake Michigan, and Illinois mark-recapture models fit the data poorly, which was evident from the large number of parameters that were inestimable, standard errors near the boundaries of theoretical thresholds (extending beyond in some cases), and the inability to achieve numerical convergence for many models. The poor fit of these models is most likely due to extremely low recapture/ recovery rates, but may also be due to bias introduced through assumption violations such as tag loss. Although specific design criteria will depend on the questions desired to be answered, we also recommend several important considerations for future tagging studies.