Project Account Number: R/EC-01-99
PRINCIPAL INVESTIGATOR: John M. Dettmers
INITIATION DATE:  February 1, 1999
COMPLETION DATE: July 31,1999
AFFILIATION: Illinois Natural History Survey

John Dettmers
Illinois Natural History Survey
Lake Michigan Biological Station
400 17th St.
Zion, IL  60099-0634
Phone: (847) 872-8677
Fax: (847) 872-8679
dettmers@inhs.uiuc.edu

OBJECTIVES

1. Count zooplankton already collected from Green Bay

2. Contribute to a lakewide understanding of mechanisms limiting recruitment of yellow perch

3. Provide information useful to fisheries managers.

METHODOLOGY
Zooplankton samples will be counted and identified to determine the abundance of specific zooplankton taxa.  Zooplankton will be identified to genus for all cladocerans, except Daphnia, which will be identified to species; copepods will be identified to family and rotifers will be enumerated.  Zooplankton will be subsampled in 1-mL aliquots and counted until at least 100 individuals of each taxon or five replicate subsamples have been completed for each sample.

RATIONALE
In Lake Michigan, little is understood about how or when year-class strength of most nearshore fishes, including, yellow perch, is set or what conditions influence year-class strength.  The relationship between growth and survival of YOY yellow perch to food availability (i.e., zooplankton density) is one factor useful to examine in an effort to better predict year-class strength of yellow perch.  Given this potential importance of food availability to early survival of yellow perch, a collaborative research effort among state and federal agencies and several universities has begun to collect zooplankton samples simultaneously with their sampling for larval yellow perch, but provisions to count all of these samples have not yet been made. A full comparison of food availability with yellow perch abundance estimates will allow the collaborative research effort a chance to make a stronger and more complete comparison of the potential success of yellow perch as it relates to food availability.  Understanding the degree to which these processes affect growth and survival of nearshore fishes in Lake Michigan can provide useful predictive information to managers as they strive to regulate harvest of important sport and commercial fishes like yellow perch.