Yellow Perch YOY assessment 2009

Yellow perch young-of-the-year assessment – WDNR, 2009

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 a micromesh gillnet at index stations. In the summer of 2009, 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 the 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 5; Kenosha -2, Racine -2, Milwaukee -5, Port Washington -3 and Sheboygan -3.

Each station was sampled at least twice during the sampling period (8/24/2009 -9/15/2009). A total of 5,800 ft of seine hauls were conducted at fifteen stations, capturing 7 YOY yellow perch. The overall CPE (catch per 100 ft seine haul) for all stations combined was calculated as 0.12 YOY yellow perch per 100 ft of seine haul. The average total length of YOY perch caught during the season was 37mm. They ranged from 32mm to 42mm. These perch were significantly smaller compared to the average size of YOY perch captured in 2008 which was 52.7mm. Sampling stations at Sheboygan and Kenosha did not produce any YOY yellow perch (Port Washington -1, Doctors Park – 1, South Shore beach – 1, Myers Park – 1, and North Pier, Racine -3; Table 1).

In general, the seining conditions were reasonably good at all stations. The days were sunny with mild wind, and the water was calm and clear. The density of cladophora was not prohibitive for seining except for a few stations like the Bender Park site which had dense algal mats making it hard to pull the net. The surface water temperature during the entire period of seining remained unusually cold due to an upwelling effect (personal communication – Dr. John Janssen, UW Milwaukee). The water temperature, throughout the entire period of late August and early September, remained in the high 50s, ranging from 48 to 64 ⁰F. In previous years, we have recorded water temperature in the lower 70s (0F). A total of thirteen species were represented in the catch, with alewife being the most abundant species followed by spottail shiner and longnose dace. In general, the number of fish captured in each seine haul was considerably lower in this year’s survey, probably due to the upwelling effect.

Table 1. Effort and number of fish caught (summarized by port city) in YOY yellow perch seining survey from 8/24/2009 to 9/15/2009.

^Species	^Ports
^Species	^{Kenosha Effort=1100ft; Ave. temp. = 61.8 0F}	^{Racine Effort=1025ft; Ave. temp. = 61.8 0F}	^{Milwaukee Effort=1750ft; Ave. temp. = 60.6 0F}	^{Port-Washington Effort=825ft; Ave. temp. = 62.6 0F}	^{Sheboygan Effort=1100ft; Ave. temp. = 62.8 0F}
^Alewife	³	⁵¹¹	⁶¹¹	¹⁹⁷³	⁶²⁵
^{Bloater chub}		¹	¹³	⁵	²
^{Rainbow smelt}	¹		¹⁴	⁷	³
^{Shiner spp.}				²
^{Golden shiner}				²
^{Spottail shiner}	⁹³	¹⁰⁷	⁶⁸¹	²²	⁴⁰⁸
^{Sand shiner}		¹⁵¹
^{Fathead minnow}			⁵	⁸	¹
^{Longnose dace}	¹²⁰	⁸⁸	³⁷	¹¹	¹⁶
^{Longnose sucker}				¹
^{Banded killifish}		¹	¹		¹
^{Yellow perch (adult)}
^{Yellow perch (YOY)}		⁴	²	¹
^{Round goby}		⁸	¹⁰

^{Micromesh gill net assessment:}

^{Two index stations, Wind Point and Doctors Park (Fox Point), were selected
for setting micromesh gill net. The nets were set in the nearshore water using
an inflatable boat on a calm day at depths ranging from 5 to 10 feet (Table 2)
and fished overnight. We used a 100-foot long and 5- foot deep monofilament net made of 12mm stretch mesh. Each lift consisted of
two gangs of 100 ft of net (200ft total) at each station. Two lifts were
conducted at each site. A total of eight species of fish were captured in these
nets (Table 3). The total length of YOY perch caught ranged from 52 mm to 63 mm
with an average total length of 57.7 mm which was similar to 2008 (61.5mm). We
did not catch any YOY yellow perch at Wind Point. The catch per 100 ft of gill
net (CPE) was 1.3 YOY yellow perch in 2009 survey.}

^{Table 2. Young-of-the-year yellow perch assessment using a bottom set
micromesh gillnets – 2009.}

^{Sampling site}	^Date	^{Effort (ft)}	^{Water temp.}	^{Depth (ft)}	^{# YOY yellow perch caught}
^{Wind Point}	^9/15	²⁰⁰	⁷⁰	^8-10	⁰
^{Wind Point}	^11/3	²⁰⁰	⁵⁰		⁰
^{Doctors Park}	^10/7	^{400 (2 nights)}	⁵⁶	^5-6	⁶
^{Doctors Park}	^10/21	²⁰⁰	⁵¹		⁷
^Total		¹⁰⁰⁰			¹³

^{^{Table 3. Numbers of fish captured in the YOY yellow perch micromesh gillnet
survey from 9/15/2009 to 11/3/2009 at Wind Point
and Doctor’s Park, Milwaukee.}

^Species

^{Number of fish}

^Alewife

⁴⁹

^{Bloater chub}

⁷

^{Lake trout}

⁸

^{Longnose dace}

⁶

^{Rainbow smelt (adult)}

¹¹²

^{Round goby}

⁴

^{Spottail shiner}

¹⁵⁷

^{Yellow perch (YOY)}

¹³

^{Yellow perch (adult)}

¹

^Summary:
^{Our YOY yellow perch seining survey conducted in the summer of 2009 at 15
stations in the near-shore waters of Lake Michigan from Kenosha to Sheboygan
produced only 0.12 young-of-the-year yellow perch per 100 ft of seine haul. One
of these sites, a beach area near the Port Washington Power Plant was new this
year. We tried this location as a potential replacement to an inner harbor site
that was recently dredged and can no longer be seined. Seining conditions were
generally good, except for a few stations which had dense mats of algae. For
example, the Bender Park beach site was choked with Cladophora and could not be
effectively sampled while other sites like Racine and Kenosha had dense algal
growth on the bottom which clogged the nets making the seining less effective.}

^{The surface water temperature remained cooler through out the sampling season
in the lower 60s (0F) at most of the stations. In the first round of seining
(August 24th and 25th) the surface temperature ranged from 48 0F to 58 0F. Since
the water temperature was still cool in late August and early September, we
attempted to conduct one more round of seining on September 14th and 15th when
the water reached 700F. However, this second round of seining did not capture
many more YOY yellow perch.}
^{Compared to 2007 and 2008, the CPE in 2009 is very low (Figure 1). We had
observed a similar CPE in 2006 (0.02). Similarly,
in the 2009 survey, the CPE of YOY yellow perch from micromesh gill net was also
much lower (1.3 YOY yellow perch per 100 ft of gill net) than the previous three
years (Figure 2). It is possible that the prevailing cold water due to the upwelling
effect may have had some effect on
the density and distribution of young-of-the-year yellow perch in the nearshore
waters.}
^{We extended the micromesh survey into the month of November. We set a
micromesh gill net on November 3rd at Wind Point. The water temperature had
dropped to 500F at this time, and we caught very few fish in the nets. No YOY
yellow perch were captured. It was interesting that lake trout had moved into
the shallow waters as we captured a total of seven adult lake trout in the net.
In general, spottail shiners and smelts dominated the catch in the micromesh
gill net. We did not capture a great number of alewife, probably due to cool
nearshore water.}}

^Species	^{Number of fish}
^Alewife	⁴⁹
^{Bloater chub}	⁷
^{Lake trout}	⁸
^{Longnose dace}	⁶
^{Rainbow smelt (adult)}	¹¹²
^{Round goby}	⁴
^{Spottail shiner}	¹⁵⁷
^{Yellow perch (YOY)}	¹³
^{Yellow perch (adult)}	¹