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Yellow perch young-of-the-year assessment – WDNR, 2008

 Beach seining:

Each year the young-of-the-year (YOY) survey of yellow perch is conducted in the nearshore waters of Lake Michigan using a beach seine and micromesh gillnet at index stations.  In most years, the survey is conducted at the same stations for the sake of consistency and repeatability.  In the summer of 2008, beach seining was conducted following a standard operating procedure (WDNR 2008) at fifteen stations from Kenosha to Sheboygan .  A 25-foot bag seine was pulled in nearshore waters, either parallel or perpendicular to the shoreline.  Generally, two 100-ft pulls were taken at each station.  All fish species collected were tallied, and up to 50 YOY yellow perch were measured (total length in mm) at each station.  Total number of all fish species captured by each port city is summarized in Table 1.  The number of stations at each port city varied from 2 to 6; Kenosha -2, Racine -2, Milwaukee -6, Port Washington -2 and Sheboygan -3. 

 Each station was sampled at least twice during the sampling period (8/25/2008 -9/17/2008).  A total of 4,790 ft of seine hauls were conducted at fifteen stations, capturing 146 YOY yellow perch.  The overall CPE (catch per 100 ft seine haul) for all stations combined was calculated as 3.05 YOY yellow perch per 100 ft of seine haul.  Most of the perch were caught in the Sheboygan area, mainly at Lake View park jetties.  The average total length of YOY perch caught in this station was 52.7mm.  Sampling stations at Kenosha and Racine ports did not produce any YOY yellow perch, and very few were captured in Milwaukee and Port Washington area (Klode park -1, McKinley marina beach -3, and Harrington beach -1; Table 1).

 In general, the seining conditions were reasonably good at all stations.  The density of cladophora was not prohibitive for seining although a few stations had dense algal mats making it hard to pull the net.  The surface water temperature was in the lower 70s (⁰F) at most of the stations.  A total of sixteen species were represented in the catch, with alewife being the most abundant species followed by Spottail shiner.

 Table 1.  Number of fish caught (summarized by port) in beach seining effort from 8/25/2008 to 9/17/2008.  

Micromesh gillnet assessment:

Two index stations, Wind Point and Doctors Park , were selected for setting micromesh gillnet.  The nets were set using an inflatable boat on a calm day at depths ranging from 6 to 11 feet (Table 2) and fished over night.  Two kinds of nets were used in the assessment: a 40-foot graded mesh gillnet made of four meshes (12mm, 20mm, 24mm and 12mm stretch mesh), each 10-foot long, and a 100-foot net made of 12mm stretch mesh, and 5 feet deep.  The first lift at each station consisted of two gangs of 100 ft net (200ft total) and one gang of 40 ft net, set to fish overnight.  The second lift at each station consisted of only two gangs of 100 ft net.  A total of ten species of fish were captured in these nets (Table 3).  The YOY yellow perch were captured mainly in the 12mm stretch mesh.  The average total lengths of YOY perch caught in the gillnet were 61.5mm and 63.6mm at Doctors Park and Wind Point, respectively.  The catch per 100 ft of gill net was 2.6 YOY yellow perch.

 Table 2.  Young-of-the-year yellow perch assessment using bottom set micromesh gillnet – 2008.  

 Table 3.  Number of fish captured in micromesh gillnet effort from 9/25/2008 to 10/14/2008 at Wind Point and Doctor’s park, Milwaukee .

Summary:

Seining survey conducted in the summer of 2008 in 15 stations in the near-shore waters of Lake Michigan from Kenosha to Sheboygan produced only 3.05 young-of-the-year yellow perch per 100 ft of seine haul.  Seining conditions were generally good, except a few stations which had greater density of algae.  The surface water temperature was in the lower 70s (⁰F) at most of the stations.  Most of the YOY yellow perch caught during the survey came from one station, Lake View Park jetties in Sheboygan .  Compared to the previous years, 2005 and 2007, the CPE in 2008 is very small.  Also, the YOY yellow perch were captured in several stations in 2005 and 2007 as opposed to one major station in 2008.  The CPEs in 2005 and 2007 were 39 and 34 YOY yellow perch per 100 ft of seine haul, respectively.  Only one YOY yellow perch was caught in the 2006 survey with a CPE of 0.02.  Based on the data from other assessments conducted annually, the 2005 year-class appears to be one of the strongest year classes produced in recent years which coincided with the findings from the seining survey.  

Similarly, the CPE of YOY yellow perch from micromesh gillnet in the 2008 survey was lower than the previous three years.  The CPEs from 2005, 2006 and 2007 were in the order of 195, 61 and 11 YOY yellow perch per 100 ft of gillnet.  It is difficult to predict how the 2008 year-class will shape up at this point.  However, the preliminary indices are lower than the past three years.