In 2008 we used the original 40-foot-long graded mesh size nets along with 100-foot-long nets of 12 mm stretch mesh. A seining survey was conducted in 2020 that yielded 0.83 yoy perch per 100-ft seine pull.įrom 2004 through 2007, mesh sizes varied but were in the range of 6 to 10 mm bar mesh in 100-foot-long nets. Due to budget constraints, we did not conduct any YOY perch beach seining in 2017, 2019, or 2021.
In 1989, we caught 18.2 yellow perch per unit of effort. Two 100 foot pulls are made directly toward shore or parallel to shore depending on wave conditions. From 1989 through 2001 we sampled at 18-22 stations, but the number of stations was reduced to 14 starting in 2002 due to decreased lake levels, increased Cladophora, and access suitability. In Wisconsin, we use a 25-foot bag seine to sample index stations between Sheboygan (north) and Kenosha (south). A review of work in inland lakes suggests that post-larval perch move nearshore during the day, which emphasizes the need to trawl different depths nearshore to track movements of fish. Until recently, YOY yellow perch have consistently appeared inshore seines in fall when littoral trawling has failed to find them. They were compared with the relative efficiencies of beach seines and bottom trawls, the two most commonly used types of gear, so that all agencies can contribute to lake-wide abundance data. Index stations were added to the Michigan shoreline, where none existed before to improve the utility of YOY abundances as a predictor. Young-of-the-year (YOY) yellow perch abundances have proven to be a relatively effective predictor of future year-class strength. Young-of-the-Year Sampling (1989 - Present) In Wisconsin, adult yellow perch have been sampled during the spawning period using 4圆-ft double-ended fyke nets with a 100-ft leader between the two double-throated pots (1997 - 1999), a 6x10 commercial double-ended fyke nets with a 500-ft leader (1998) and with standard 2 1/2 inch commercial gill net (1997) and WDNR graded mesh gill net (1997- present).Īfter a thorough review comparing raw data with electronic and table summary data, minor changes have been made to this table and its summaries. The main objectives of the yellow perch spawning assessment are to collect information on spawning fish, including length, weight, sex, condition, collect gametes for scientific studies, determine spawning sites and aid in any other lake-wide studies such as tagging and toxicological analysis. Yellow Perch Spawning Assessment (1997 - present) However, after the females from the 1998 year-class matured, we found good numbers of egg masses distributed on the Green Can Reef from 2001-2007. In 1998, divers searched for 12 hours and 48 minutes and found 0 egg masses or 0.0 egg masses per 1000 square meters. In 1997, divers searched for eggs for 31 hours and 40 minutes and found a total of 9 egg masses on the transects or nets or 0.50 egg masses per 1000 square meters. During the initial years of the survey, we found very few egg masses. The purpose of doing these dives was to identify sites where egg masses were found and to develop an index of relative annual egg densities. All egg masses along a 300-meter transect were counted. Yellow perch egg masses were identified by SCUBA divers at sites that 1) attract spawners, 2) were likely to trap drifting egg masses or 3) were traditional spawning grounds. Yellow Perch Egg Deposition (1997 - Present) In addition, several other studies have been conducted, including an alewife stomach content study, a lake-wide mark and recapture study and a reproductive status study. These assessments include 1) egg deposition, 2) spawning, 3) young-of-the-year (YOY) and 4) winter graded-mesh. The WDNR, along with other agencies and scientists, has used a variety of assessments to analyze the status of the current yellow perch population. The number of YOY perch captured lake-wide has dropped dramatically since 1988. Annual surveys of young-of-the-year (YOY) perch using micromesh gill nets and beach seines in the fall are usually good indicators of the number of fish hatched in a given year that we can expect to see as adults in future years. A large decline in the number of yellow perch surviving their first year of life has caused a reduction in the number of perch in Lake Michigan.
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