Walleye hatch again lower than expected

Sandusky, Ohio – At the October Western Basin Sportfishing Association meeting, Travis Hartman, fisheries biologist with the DNR Division of Wildlife Sandusky Lake Erie Fisheries Research Station, gave an overview of the current Lake Erie walleye and yellow perch populations.

Walleye Research

He explained the different methods used to determine current and future walleye populations including fall gill netting, creel surveys, and trawling for walleyes and additionally the use of commercial fish catch rates for other species.

Gill netting and creel surveys, arguably the largest freshwater angler interview effort in the world, help determine age class structure, growth, fishing effort, and catch rates. Through the use of the more accurate method of aging fish through otoliths (inner ear bones) instead of scale rings, recent research has indicated that Lake Erie walleyes live more than 20 years.

The oldest fish are not necessarily the biggest fish, but faster growers. Many of the walleyes measuring over 31 inches are only 12-19 years of age, with one 32-incher being determined to be only 15 years old. An older fish determined to be 22 years old was only 28 ½ inches long.

Trawling is primarily used to predict the expected number of walleyes that will enter the fishery in two years. The long-anticipated results of the August trawling numbers are disappointing in light of the early, warm spring and hot summer. Many lake watchers hoped these conditions would translate into a long, productive growing season for young of year fish.

Instead, the drought reduced lakewide productivity (algae and zooplankton production) and turbidity (muddiness), which are factors that offer the best feeding conditions for fry while minimizing predation from white perch, alewife, and (rainbow) smelt.

These invasive species have been shown to have higher survival rates during mild, ice-free winters, such as we had last year. When they are abundant, they take a higher toll on eggs and fry.

Walleye Hatch Results

Instead of the old scoring system of calling a hatch “poor, fair, good, or excellent,” young of the year fish caught during the August trawls are calculated to reflect the geometric mean number of fish per hectare.

The geometric mean (average) calculation is used to dampen the “hit and miss” effect of huge fluctuations of numbers caused from going through clouds of fish or missing them altogether while trawling. A hectare is a metric unit of measurement for an area 100 meters by 100 meters or approximately 2.5 acres in size. (1 meter is a little longer than a yard at approximately 39.4 inches and 100 meters is approximately 109 feet)

This year’s hatch (2012) was calculated to be 2.00 per hectare. This is higher than last year’s 1.76/ha, 2006’s 0.33/ha and 2002’s 0.05/ha but far short of 2010’s 7.28/ha, 2007’s 8.84/ha and especially 2003’s 54.49/ha.

An average hatch in recent years has produced nine walleyes per hectare, which provides 10 million catchable fish two years later. Natural and fishing mortality removes over one-third of the walleyes from each catchable age year class annually.

Hartman pointed out that after the zebra mussel infestation in 1988, Lake Erie can no longer consistently support the higher numbers of fish possible prior to the invasion of this exotic species. Lake Erie frequently produced Ohio harvests in excess of 4 million walleyes per year from a population that may have been over 70-80 million strong.

An exception was in 2005, two years after the unexplained “monster” 2003 hatch, when the number of walleyes in the lake was estimated to be over 83 million. Due to conservative harvests, we are still catching many fish from this hatch, including a high majority that are of trophy size.

As the population levels out, Hartman predicts that the “new normal” is likely to remain in the 20-30 million range that will provide about 1 million walleyes per year in Ohio.

Walleye catches in Ohio were at about 417,000 last year, but may approach the 1 million fish mark this season after the data are tabulated. Over 763,000 had been tallied through August by private boat anglers, with charter boat trips typically adding an additional 10 percent to the total bag.

Walleye catch rates are not much different than they were in the 1980s at 0.35+/angling hour in 2010-2012 (partial) decade, compared to 0.45 in the 1980s, 0.33 in the 1990s and 0.41 in the 2000s. This is likely due to the reversal of anglers castinag vs. trolling, which went from 70 percent casting/30 percent trolling in the 1980s to virtually the opposite, 27 percent casting/70 percent trolling now (3 percent unspecified).

Angling hours went from 12 million in the late 1980s to a low of less than 3 million last season, due to the widespread algae bloom, but returned to over 3 million again this year. The days of walking across boats from Davis-Besse to West Sister Island are over.

Yellow Perch

The yellow perch catch in 2011 by anglers was 4.156 million fish. The population is dominated by bigger fish from good hatches in 2007 (130.3/ha) and 2008 (51.2/ha). The good news is that there are fewer throw-backs in the catch lately, but the bad news is that there will be fewer keepers in 2014 and later as these older fish disappear.

Commercial trap netting in the western basin was suspended this season to avoid impacting the lower populations and concentrate on the healthier numbers within the Lorain to Conneaut portion of Lake Erie.

Yellow Perch Hatch

Perch in 2012 had a hatch of 23/ha, two-thirds fewer than the average of 70/ha. There was a very large hatch of 333.4/ha in 2003, but with a lifespan closer to 10 years, these perch will soon be out of the picture.

There was better reproductive success in the central basin of Lake Erie, so anglers may want to direct future perch fishing activities from Fairport to Conneaut. Growth rates have been better there due to favorable water temperatures with good food supplies during the peak summer months.

Yellow perch eat a variety of bottom life, including midge and mayfly larvae. When suspended, they also eat minnows and zooplankton.

Ice This Year?

As of now, a weak El Niño has been forecast for this fall and winter, raising the uncertainty of the prospect of ice cover this year. For the sake of a good hatch in 2013, it would take the lake having a good ice cover for a month or two.

Categories: Feature, News, Walleye

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