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Yellow perch spawning and egg deposition survey in Lake Michigan waters near Green Can Reef, Milwaukee - 2009

In 2009 spring, a yellow perch spawning survey in the Lake Michigan was conducted from 5/19/2009 to 6/10/2009. The survey was done in the vicinity of Green Can Reef off Milwaukee. Four gillnet lifts were conducted on 5/19, 5/28, 6/2 and 6/10/2009. The effort per lift varied from 500ft to 1000ft of net. Each box (500 ft) consisted of five different mesh sizes – 2, 2 ½ , 2 ¾ , 3 and 3 ¼ inch mesh 100ft each. The nets were set at different depths, ranging from 30 ft to 59 ft. The bottom temperature ranged from 48 F in the beginning of the season to 52 F in the later part. 

A total of 629 yellow perch were caught in four lifts of 3,500 ft gillnet effort – 465 males and 164 (26%) females. On May 19th, the majority of perch were still green with no spent individuals (Table 1). The bottom temperature was 48.2 F and Secchi depth transparency was 33 ft. The final lift was taken on June 10th when we observed 91% of the males being spent and the remaining were ripe, and 55% of females were spent. Although there were still 32% green females at this time, the spawning activity had peaked. The bottom temperature had gone up to 52 F. 

Age distribution:

We collected a subsample of 100 age samples (anal spines) during the survey. Age samples of ten males and 10 females from each mesh totaling 50 males and 50 females were analyzed. Age 7 and age 4 yellow perch belonging to the 2002 and 2005 year-classes comprised the majority of perch on the spawning ground followed by age 11 (1998 year-class) and age 6 (2003 year-class). It was encouraging to see multiple year-classes represented in the spawning population.

 Total area searched = 38,182m²

Total eggs found = 222

Egg masses per 1000 m² = 5.8