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 30 – September 13, 2004. A standard protocol was used for sampling using 25’X4’ beach seine with ¼" delta mesh. We sampled 15 sites distributed along the shoreline from Kenosha in the south to Sheboygan in the north. At each location we attempted two pulls of approximately 100’ each in the shallow water perpendicular (parallel, when deeper) to the shore. We repeated the same approach at each site during the second visit. 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 we used a 100 ft. Swedish monofilament gillnet with 6.35mm bar mesh. The nets were set in the morning and lifted on the following morning allowing about 24 hours in the shallow water (4-5ft deep). We selected two locations as index sites, Wind Point – about 17 miles south of Milwaukee, and Fox Point – about 9 miles north of Milwaukee. These sites were shallow with rocky and gravel bottom. All fish were identified to species level and tallied. All YOY yellow perch were measured in mm (total length). Sampling dates were 9/23/04 and 10/7/04 at Wind Point, and 9/30/04 and 10/7/04 at Fox Point.
Results and Discussion:
Weather conditions were reasonably good in most sites, especially in the 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 on the cooler side at all locations, in the 60’s (F). We completed two rounds of seining by revisiting the same site twice during a period of two weeks. A total of 23 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 19 YOY yellow perch were captured in the entire survey with an effort of 4,660 ft. of seine haul. These 19 YOY were captured at 5 different locations – Sheboygan North Pier Jetties, Sheboygan North Pier, Doctors Park, Klode Park, and Meyers Park. The catch per 100 ft. of seine haul turned out to be 0.4 YOY yellow perch in this year. The other species recorded include: fathead minnow, blunt nose minnow, sand shiner, johney darter, golden shiner, sculpin, white sucker, rainbow smelt, bloater chub, gobi, stickle backs (9-spine), rock bass, black crappie, northern pike, bluegill sunfish, small and largemouth bass, carp, golden shiner and common shiner.
Based on the index site sampling data it appears that the natural reproduction of yellow perch in this part of the lake is still 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 YOY yellow perch at both the places. The cladophora algal mass did not clog up the nets as much to hinder the effectiveness of gill nets. No YOY perch was caught at the Wind Point site on 9/23/04. Twelve YOY yellow perch were caught on 10/7/04, ranging from 58 mm to 66 mm. Majority of YOY yellow perch captured in the gill net fell in the range 60-64 mm. This could be a function of the gill net mesh size (6.35 mm bar mesh) that was deployed. Other species captured included alewife (both young and adult), rainbow smelt, chub, longnose dace, johney darter and spottail shiner. Adult smelts appeared in large numbers, dominated the catch on 10/7/04. The Fox Point gill net set had 2 YOY yellow perch (61 mm and 65 mm) on 9/30/04, and 5 YOY yellow perch (ranging from 56 mm to 64 mm) on 10/7/04. The catch per 100 ft of net (CPE) comes out to be 3.5 YOY yellow perch at Fox Point, while CPE at Wind Point is 6. Both sites have rocky substrate and bed rock. The other species in this site included alewife (young and adult), longnose dace, spottail shiner, fathead minnow, chub, and smelt.