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Yellow perch spawning and egg deposition survey in Lake Michigan waters near Green Can Reef, Milwaukee - 2003

This assessment has been conducted on the Green Can Reef and in the Milwaukee harbor. The objective is to quantify the relative abundance of mature female perch in previously identified spawning areas. We conducted our first gillnet lift on 5/28/2003 at depth range 31-65 ft. with a total effort of 1250 ft. net. A total of 894 yellow perch were captured, of which 15 were females. Only 2 out of 15 females were ripe at this time. The bottom water temperature was 47 ⁰F. The majority of the yellow perch captured came from nets set at 31-32 ft. of water. The second lift was taken on 6/3/2003 when the water temperature was still 46 ⁰F at the bottom. A total of 715 (11 females) yellow perch were captured in 450 ft. of gillnet. At this time, 7 females out of the 11 were spent, 3 were green. We collected anal spines from 50 males and 27 females for age determination. Overwhelming majority of the yellow perch (94%) on the spawning reef belonged to 1998 year-class.

The following table summarizes the catch per effort (CPE) per 1000 ft. gillnet by depth categories.

Sampling date	Net depth (ft.)	CPE (all perch)	CPE (male)	CPE (female)
May 28, 2003	Shallow (31 – 32)	1284	1280	4
	Deep (63-65)	35	23	12
	Intermediate (44-47)	770	750	20
June 03, 2003	Intermediate (35-45)	1589	1565	24

2003 – yellow perch egg deposition survey:

The WDNR dive team continued the effort using the protocol similar to 2002 to quantify egg deposition in the Green Can Reef area.

2003 Diving for yellow perch egg deposition
Date	Divers	Depth	Location	Area searched	# of egg masses
June 5	Paul Peeters	42	East of Green Can	15	9
	Brad Eggold			15	10
June 5	Tim Kroeff	35	West of Green Can	15	15
	Mike Baumgartner			15	11
June 5	Paul Peeters	48	East and North of Green Can	15	2
	Brad Eggold			15	6
June 5	Tim Kroeff	35	West of Green Can	12	12
	Mike Baumgartner			12	12
June 9	Tim Kroeff	42	West of Green Can	20	22
	Mike Neal			20	15
June 9	Paul Peeters	42	South of Green Can	20	10
	Brad Eggold			20	10
June 9	Tim Kroeff	40	South of Green Can	15	40
	Mike Neal			15	30
June 9	Paul Peeters	43	West of Green Can	20	25
	Brad Eggold			20	17

Total Area searched = 24,526 m²

Total eggs found = 246

Egg masses per 1000 m² = 10.04

Overall, the density of egg deposition in 2003 was similar to the 2002 observations (11.53 egg masses per 1000 m² in 2002).