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Young-of-the-year yellow perch assessment in Wisconsin waters of Lake Michigan – 2006

The yellow perch population in Lake Michigan continues to be a major concern.  Our winter 2006 assessment centered around examining the age distribution and year class strength of the yellow perch population with an emphasis on 3 year-old fish.  Age 3 is the earliest age at which we feel confident that young yellow perch have survived the natural high mortality associated with being a small fish.  Results from this assessment show that the 2002 year-class (now 4 year-olds), were fairly well represented in the catch representing 33% of all the fish caught, although not as strongly as the 1998 year-class (55%).   The 1998 year-class continues to dominate the catch in this assessment even though other year-classes have been found.  In addition, we have noticed a very small number of age 3 yellow perch indicating poor survival of 2003 year-class.  

Large numbers of mature adults (comprised mostly of fish from the 1998 year class) congregated on the spawning grounds during our spawning assessment in May-June, 2006.  We documented a significant number of 2002 year-class yellow perch (29%) on the spawning grounds, in addition to the still dominant 1998 year-class (61%).  The WDNR dive team made several dives during this period and recorded the third highest egg mass numbers since the start of the survey. 

The 2006 young-of-the-year (YOY) assessment conducted in August and September each year using beach seines and small graded mesh gill nets.  The catch per 100 ft of effort (0.02) from the beach seining study showed very few YOY yellow perch.  However, the small mesh gill-net data in the index sites showed moderate number of young perch when compared to the 2005 data.  We caught 61 YOY yellow perch per 100 ft of effort in 2006 when compared to 195 per 100 feet in 2005.

The commercial fishery for yellow perch remains closed and the sport bag remains five fish per day.  Sport fishing is closed from May 1 – June 15.  This closure period is now a permanent rule, and will remain in effect for the foreseeable future.  Protection of spawning stocks during the peak of the spawning season is critical to any population.  The impact on the food web as a result of exotic species interactions and changes to spawning habitat are all factors in how well the population of yellow perch can recover.  The existence of a well-represented 2002 year class, and a potential strong 2005 year-class is very encouraging, but it may be that recovery to population levels that we enjoyed prior to the early ‘90’s is not a realistic expectation given the altered environment.