The young-of-the-year (YOY) yellow perch assessment was conducted in the nearshore waters of Lake Michigan in the south east region of Wisconsin from August 25, 2003 to September 9, 2003. A standard protocol was used for sampling using 25’X4’ beach seine with ¼" delta mesh and sampled 16 sites distributed along the shoreline from Kenosha in the south to Sheboygan in the north. At each location we attempted two pulls of 100’ each in the shallow water perpendicular to the shore. All the fish captured were identified to the species level and counted. Some YOY yellow perch were preserved in 70% ethanol.
In addition to beach seining, in 2003, we used a modified Swedish monofilament gillnet. The nets were set in the morning and lifted on the following morning allowing about 24 hours in the shallow water (4-5ft deep). All the fish were identified to species level and tallied. Yellow perch, both young and adults were measured (total length in mm). Anal spine samples were taken from larger individuals for age determination. We collected scale samples from small perch for verification.
Results and Discussion:
We conducted seining survey in sixteen sites. Conditions were reasonably good in most sites in first round of seining. Some sites were choked with dead and decaying algae (Cladophora), especially in the second round, making seining difficult. Water temperature was generally in the 70’s (F). We completed two rounds of seining by revisiting the same site twice during a period of two weeks. A total of 18 species were captured in this survey. Young of the year alewife dominated the catch at all the sites followed by spottail shiner and longnose dace. A total of 6 YOY yellow perch were captured in the entire survey with an effort of 5650 ft. of seine haul. The catch per 100 ft. of seine haul turned out to be 0.1 YOY yellow perch in this year. The other species recorded include: fathead minnow, blunt nose minnow, sand shiner, johney darter, banded killifish, golden shiner, sculpin, white sucker, rainbow smelt, gobi, stickle backs (3-spine, 5-spine and 9-spine), and common shiner.
These 6 YOY yellow perch were captured in there different locations Meyers Park, Racine (1), Bender Park, Oak Creek (3), and McKinley Marina, Milwaukee (2). In addition, we caught 9 yearling yellow perch at Bender Park.
Based on the index site sampling data it appears that the natural reproduction of yellow perch in this part of the lake is still a very poor. In recent years, only 1998 produced a decent year-class which was evident in the YOY index site survey (Figure 1). It is clear that the adult yellow perch need continued protection to facilitate recovery of the population.
The data from the gill net sets were little more interesting in that that we captured good number of both young-of-the-year as well as yearling yellow perch. The algal mass and prevailing wind posed a little bit of challenge to effectively sample using gill nets. How ever, the two locations that we set nets, one off Wind Point Light House in Oak Creek and the other off Doctor’s park in Fox Point, produced quite a few yellow perch. Both sites have rocky substrate and bed rock. The presence of yearling yellow perch in these nets was certainly a good indication that 2002 year-class survived through the winter.