Yellow perch recruitment

Yellow perch supported one of the most important fisheries on the Great Lakes. However, since 1990, the Lake Michigan population has been experiencing recruitment failures. With no new fish recruiting to the population, and a fishery still in operation, the abundance of perch in Lake Michigan declined quickly. Moreover, because the gill net fishery was size-selective, larger and predominately female fish were removed from the population in disproportionate numbers. This has produced a population that is lower in abundance, composed of smaller fish overall, and with a male biased sex ratio.

To address these concerns the management agencies and academic institutions that border Lake Michigan asked the Yellow Perch Task Force of the Great Lakes Fishery Commission to develop a multi-agency research initiative to elucidate factors possibly responsible for the decline. Management agencies have increased fishery-independent monitoring to provide baseline data. The academic research response has been to develop a series of coordinated Sea Grant projects involving scientists from Wisconsin, Michigan, Illinois, Indiana, Maryland and North Carolina. The coordination between the different groups is a central feature of the research. Individual groups can only sample a limited geographic area at the temporal resolution required. However, by coordinating sampling protocols and then combining results from separate areas around the lake, the group will be able to draw inferences about the mechanisms potentially contributing to year class strength in perch on a lake wide basis.

Wisconsin Sea Grant funded two collaborative projects to work on yellow perch in Green Bay and in Lake Michigan. Fred Binkowski, (WATER Institute, University of Wisconsin – Milwaukee), Brian Belonger (WDNR), Jim Rice (North Carolina State Univ) and Tom Miller (Chesapeake Biological Lab) are PI’s on the projects. Brian Belonger (WDNR) has been monitoring perch spawning in the southern end of Green Bay for almost 20 years. He has a unique time series of spawning and larval surveys conducted around Little Tail Point. Importantly, the perch population in Green Bay does not seem to be showing the same declines as that in Lake Michigan. Consequently, the Green Bay project provides an important comparison for results from Lake Michigan.

The projects involve both field and lab components. In the field, identical sampling programs sought to follow 4 d birthdate cohorts throughout the summer, from the larval to the juvenile stage. Sampling was conducted using neuston nets, Miller high speed samplers and beach seines. Larval samples were immediately frozen for subsequent age and condition analysis. Juvenile samples were preserved for age analysis. Samples of the food base were also taken for diet information. Field samples are currently being processed. However, even from the limited data available it is clear that while larvae were abundant in Green Bay, they were extremely rare in samples from Lake Michigan.

In the laboratory, experiments focused on determining the potential role of maternal effects on larval survival and growth. Half-sib groups from 10 different females were produced by artificially fertilizing the eggs of females collected from gill nets set in Lake Michigan. Research aimed to answer two questions: Are there maternal effects, and for how long can they be detected. A replicated experiment in which half sib groups were either fed or starved was used to address both questions. The fed group were followed for 30 days following hatching, to a size at which they would switch from the pelagic to a benthic mode. Larvae were sampled every 2 d from the tanks to assess growth and condition. Results are currently being analyzed. The data collected in the laboratory will be used to explain patterns observed in the field collections.

Perch Publications

Heyer, C. J., T. J. Miller, F. P. Binkowski, E. M. Caldarone and J. A. Rice. 2001. Maternal effects as a ecruitment mechanism in Lake Michigan yellow perch (Perca flavescens). CJFAS 58:1477-1487

Last revised: 11/14/2003