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Young-of-the-year yellow perch beach seining survey 2007 – Lake Michigan , SER, WDNR

Yellow perch spawn in late May to early June in the Wisconsin waters of Lake Michigan .  By the end of August the young yellow perch move into nearshore waters for feeding and shelter.  Wisconsin DNR conducts an annual beach seining survey during late August and early September at index stations that are located between Kenosha and Sheboygan .  In 2007, we surveyed fourteen different sites using a 25’ bag seine, pulled in the shallow inshore waters.  At each site, depending on the water depth, two 100’ pulls were taken either perpendicular or parallel to the shoreline.  Each index site was visited two times between 8/27/07 and 9/05/07.  All fish captured at each pull were identified to the species level and tallied.  At each location, the first 50 young-of-the-year (YOY) yellow perch were measured to the nearest mm (total length), and remaining perch were tallied.  We captured 1443 YOY yellow perch in five days of survey.  The average total length of the YOY yellow was 58mm, and they ranged from 44mm to 76mm.  The young perch appeared healthy.  

A total of eighteen species of fish were captured during the survey (Table 1).  The individuals comprised of both young and adult fish.  The YOY alewife dominated the catch (117 alewife per 100’ of seine haul), and occurred throughout the survey area.  The YOY yellow perch also occurred in all five harbor sites with an overall CPE (catch per effort) of 34 YOY yellow perch per 100’ of seine haul.  This is the second biggest CPE value since the WDNR began seining survey in 1989.  In 2005, we captured 1,934 YOY yellow perch with a CPE of 39 perch per 100’ of seine haul.  However, in 2005 survey, most the YOY yellow perch were captured in a single location as opposed to the wide distribution of YOY yellow perch observed in 2007.  In 2007, of the fourteen sites sampled, we captured YOY yellow perch in nine different sites (Table 2).  Although, we put in a similar effort in 2006, only one individual YOY yellow perch was captured.  Data from egg deposition survey indicated a similar egg deposition density in 2005, 2006 and 2007.  A combination of successful spawning and hatching, and subsequent ecological conditions available for larvae determine the survival and growth of YOY yellow perch.  In addition, appropriate weather conditions and water quality of the sampling sites determine the success of seining effort.  This was evident in the 2007 survey when lake conditions were relatively more congenial for seining on September 5^th compared to other sampling days (Table 2).

Table 1.  Number and catch per effort (CPE) of various species of fish captured during the seining survey in the nearshore waters of Lake Michigan , SER, WDNR - 2007  

 Table 2.  Number of YOY yellow perch captured at each site using beach seine in Lake Michigan waters of south eastern Wisconsin from 8/27/07 to 9/05/07.  

Small-mesh gillnet survey (from Dr. J. Janssen)

In addition to the beach seining effort, we used a small-mesh gillnet with two different mesh sizes, 6mm and 8mm bar mesh, set at index sites to sample for small yellow perch.  The index sites – Fox Point and Wind Point – and effort remained consistent with the previous year’s assessments.  A 200-ft gillnet, comprised of 100 ft - 6mm  and 100 ft  - 8mm bar mesh tied together, was set in 5 ft of water on rocky substrate and fished overnight.  The first lift occurred on 8/28/2007 at Fox Point where 13 YOY yellow perch were collected.  These perch had an average total length of 60mm which was similar to data from our beach seining survey.  A second set and lift was conducted at Wind Point on 9/12/2007 and 32 YOY yellow perch were captured.  The average total length of these perch was 58mm.  Combining the data for the two sites, the catch per effort (CPE) for the gillnet survey was 11 YOY yellow perch per 100 ft of gillnet in 2007.  This is significantly lower than the 61 YOY yellow perch per 100 ft of gillnet found in the 2006 survey.