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DNR fisheries marking walleye fry to evaluate stocking levels

May 21, 2012

by Chris Schultz

From the DNR

Minnesota Department of Natural Resources (DNR) fisheries biologists began an eight-year study in 2008 to determine the optimum number of walleye fry that should be stocked back into lakes where eggs are removed for stocking purposes.

The first phase of the study focused on marking walleye fry using oxytetracycline (OTC) to differentiate stocked fry from those naturally produced.

The last phase will now focus on determining the growth and survival of these marked fish to catchable size.

“This is a cutting edge fisheries research project,” said Dale Logsdon, DNR fisheries research biologist in Waterville. “It uses technology to better understand biology and to help guide management practices that result in the maximum number of walleyes for the public to catch and enjoy.”

Annually, the DNR collects walleye eggs from 13 different spawning runs as part of a statewide walleye production and stocking program.

Lakes supporting these spawning runs represent some of the most prolific walleye fisheries in the state.

The importance of assuring that hatchery operations do not have negative impacts on these fisheries has long been recognized.

To compensate for possible impacts of these egg removals, the DNR has historically stocked at least 10 percent of the walleye fry hatch back into those lakes where eggs were removed.

However, the effects of these compensatory stockings had never been thoroughly evaluated due to the inability to distinguish between natural and stocked fry.

DNR fisheries biologists want to ensure that enough fry are returned to the lakes, but are also concerned that stocking too many fry could result in poor growth and survival of both wild and stocked fish, thus resulting in fewer catchable walleye in the population.

Too many young walleye in the system at one time can result in increased competition for food, reduced growth rates, increased foraging times, and greater vulnerability to predation, according to Logsdon.

“We want to optimize fry abundance to help ensure that we are maintaining the health of the walleye fisheries in our egg-source lakes.”

With the advent of the OTC technology, fisheries researchers are able to mark newly-hatched walleye fry by immersing them in a solution of OTC for several hours, just before they are stocked.

The fry absorb a small amount of this chemical, resulting in a harmless mark left on the fish otolith, or ear bone, that can be detected years later using a microscope and ultraviolet light.

“This new technology enables us to determine how many walleye in a population originate from stocking versus natural reproduction,” Logsdon said. “If a florescent mark is present, we know we are looking at a stocked fish.”

Four egg-source lakes – Woman, Winnibigoshish, Otter Tail and Vermilion – are included in the study.

These lakes were chosen because of their ecological characteristics and the availability of historical fisheries data.

The study’s has two main objectives are to better understand the natural reproductive processes in these lakes, and to use this information to identify the optimal number or replacement fry to stock in relation to natural changes in spawner abundance.

Fisheries personnel stocked marked fry at predetermined levels during the first five years.

Gill net surveys will continue the next three years to learn what fry densities maximize survival, growth and abundance.

Achieving these target fry densities will likely require adjustments of historical stocking rates.

This study continues the DNR’s history of implementing research projects that aim to improve the understanding and management of the state’s fishery resource.

Minnesota, one of the nation’s top five angling destinations, continues to provide some of the nation’s best fishing.

For more information on the walleye fry marking research project, contact the local DNR fisheries office nearest the study lake.

Fawns born in May; DNR urges people to leave them alone
From the DNR

May is the month when most fawns are born. The Minnesota Department of Natural Resources (DNR) is urging people to leave fawns and other wildlife alone.

While a new fawn may appear helpless, it is important to stay away and not interfere with the doe’s natural instinct for raising its young.

A doe’s method of rearing offspring is different from a human’s, especially for the first few weeks.

Within hours of birth, the fawn is led to a secluded spot and the doe lets it nurse.

With a full stomach, the fawn is content to lie down and rest. If the doe has twins, it will hide the second fawn up to 200 feet away.

Then the doe leaves to feed and rest herself, out of sight but within earshot.

In four or five hours, she will return to feed her young and take them to a new hiding place.

They follow this pattern for two to three weeks, and only then, when the fawns are strong enough to outrun predators, do the young travel much with their mother.

Deer have evolved a number of special adaptations that make this approach to fawn rearing successful.

Fawns have almost no odor, so predators cannot smell them.

Their white spotted coats provide excellent camouflage when they are lying on the forest floor.

For the first week of life, frightened fawns instinctively freeze, making full use of their protective coloration.

Older fawns remain motionless until they think they have been discovered, and then jump and bound away.

A deer’s primary protection from predators is its great speed.

Newborn fawns are not fast enough to outdistance predators, so they must depend on their ability to hide for protection.

Although these adaptations work well against predators, they don’t work very well with people.

For the first few weeks, a fawn’s curiosity may entice it to approach a person who comes upon it.

What’s the right way to handle an encounter with a fawn? Never try to catch it. If it’s hiding, admire it for a moment and then quietly walk away. Enjoy the memory, but don’t describe the location to others. If the fawn tries to follow, gently push on its shoulders until it lies down, and then walk away.

That’s what its mother does when she doesn’t want the fawn to follow.

Leaving fawns alone gives them the best chance for survival.

Even most orphaned fawns are best suited to survive without human intervention.

Never feed or place a collar on a fawn or other wild animal.

Collaring a wild animal sets it apart from others and increases the likelihood for harm to the animal.

Collared wild animals are not protected from hunting or animal control activities by law enforcement.

Conditioning any wild animal to seek human-provided food will cause them to stop seeking their natural food sources.

Feeding deer can be especially problematic because it encourages the transmission of animal disease such as chronic wasting disease (CWD).

CWD can be spread through saliva when multiple deer eat from the same food source – such as feeders or piles of feed left on the ground.

Feeding deer can concentrate animals in feeding areas, which makes them more susceptible to predation, vehicle collisions or other unwanted human interactions.

What begins as a good intention to help the animal, ultimately promotes disease and lessens the animal’s ability to survive independently.

Not all animals survive, and some mortality is a natural occurrence.

For more information about an interacting with a wild animal, contact a local DNR area wildlife office for suggestions. In most cases, letting nature take its course is the best advice.

DNR urges ATV operators to ride safe and ride smart
From the DNR

The weeks leading up to Memorial Day are a time when many people begin taking their all-terrain vehicles (ATVs) out of the garage for the summer, according to the Minnesota Department of Natural Resources (DNR).

It’s also a time when the DNR reminds ATV owners and riders to ride safe and ride smart.

“The weather warms up, school is out, and it’s the time of the year that most ATV accidents happen,” said 2nd Lt. Leland Owens, DNR’s recreational vehicle coordinator.

ATV accidents claimed 82 Minnesotans from 2007-2011. More than one-half of the fatal accidents involved an ATV rolling over.

Four in 10 fatalities involved alcohol. Ages of those fatally injured ranged from 7 to 94 years old.

“ATVs are not babysitters,” Owens said. “If you allow a youth to operate an ATV, make sure the person is trained, fits the ATV, and is constantly supervised by an adult.”

Owens said the public’s perception is that most ATV fatalities and accidents involve youths, but that’s really not the case.

Recent DNR statistics show a decline in youth-involved incidents, largely due to safety training requirements for those ages 15 and under.

“It’s the adults – those who have not completed DNR ATV safety training – who are most at risk,” Owens said.

More than 95 percent of those who died had not taken ATV safety training.

State ATV laws require youth ages 12-15 and anyone born after July 1, 1987, who is 16 or older, to take ATV safety training before operating on public lands.

Owens encourages people to be defensive drivers while operating an ATV, since more than 65 percent of fatal ATV accidents took place in the road right-of-way.

Another 25 percent of ATV fatalities happened on private property.

Owens urges caution to ditch riders as well. Ditches can be full of hazards such as telephone and power poles, guy wires, electrical and phone boxes, survey markers, culverts and mailboxes.

Ditches along state and county roads are closed to ATVs in the agricultural zone from April 1 to Aug. 1. Owens suggests trailering machines to a designated ATV trail.

“When riding, stay on designated trails,” Owens said, “Don’t trespass on private property where you don’t have permission to ride. And slow down, since ATVs become less stable at increased speeds.

“Always keep safety in mind,” he said. “It just may save a life and ensure that each and every ATV rider returns home safely and ready for another ride.”

For more information on ATV regulations go to http://www.dnr.state.mn.us/ohv/index.html.

DNR auction June 2 in New Ulm features wide variety of items
From the DNR

A public auction of surplus equipment will be held by the Minnesota Department of Natural Resources (DNR) on Saturday, June 2, at 9:30 a.m. in New Ulm.

Nearly 150 lots of items will be sold including heavy equipment, dump box pick-ups with snowplows, pick-ups, automobiles, ATVs, snowmobiles, tractors, lawnmowers, mountain bikes and more.

Photos and a complete listing of items will be posted 10 days prior to the sale at www.minnbid.org.

On-site inspection of items will be available only on Saturday, June 2, from 8 to 9:30 a.m.

To avoid standing in line the day of the sale, bidders are encouraged to preregister for the auction online at www.minnbid.org.

It only takes a few minutes and also provides access to information on other auctions conducted by the state of Minnesota.

The sale is being conducted by the state of Minnesota, Department of Administration, Fleet and Surplus Services Division.

Auctioneer will be Benoit Auction Service of Dassel.

The auction will be held at the Brown County Fairgrounds, 1200 North State St. in New Ulm.

CO weekley reports
From the DNR

• CO Brian Mies (Annandale) checked anglers and boaters.
CO Mies also worked on illegal filling of lake bed.
CO Mies worked AIS work crews along with checking minnow dealers.

• CO Rick Reller (Buffalo) spent most of the week checking anglers and working AIS details on area lakes and rivers.
AIS compliance was much better than in the past, but several boaters were still unaware of the laws that have been in place for a couple of years.
Fishing activity was high, but the walleye catch was down in the area.
Most common fish found in live wells were northern pike and crappies.
Reller also assisted Ramsey PD with a suspicious person.
Enforcement action was taken for taking smallmouth and walleyes out of season, angling with extra lines and angling without a license, no PFD on watercraft and watercraft registration violations.

• CO Steve Walter (Waconia) worked most of the week on the Governor’s fishing opener on Lake Waconia giving presentations, radio interviews and security on the lake.
A call of a horse that was shot was investigated, possibly by a turkey hunter in Waconia Township. Any information please call TIP.
An AIS detail was worked on Lake Waconia.
Enforcement action was taken for failure to remove drain plugs from watercraft, no watercraft registration and no personal flotation devices.

• CO Jackie Glaser (Mound) worked the Governor’s fishing opener events on Lake Waconia.
Boats were checked for aquatic invasive species on area lakes.
Numerous boaters were found in violation of the drain plug law.
She worked a busy Lake Minnetonka finding violation of BUI, no fishing license, unattended line, no watercraft registration, no PFDs, and taking bass out of season.
Trout fishermen on Courthouse Lake were checked with most having great success.
She responded to a TIP call of fishermen taking bass out of season on Lake Minnetonka.
The boat was checked and six bass were found in a cooler.
She also worked on a background investigation.

• CO Wayne Hatlestad (Litchfield) worked the fishing opener checking angling and boating activity.
Additional time was spent on AIS enforcement.
Hatlestad also spent time checking ATV activity, assisting with academy training, and continued work on a pre-employment background investigation.
A nuisance beaver complaint was handled, and incidental fur from spring beaver season was disposed of.

• CO Brett Oberg (Hutchinson) worked a fairly productive fishing opener. 
Several anglers were able to catch at least one walleye or northern pike. 
Anglers that that didn’t have any luck were able to enjoy the near perfect weather. 
The South Fork of the Crow River was the most productive fishery in the area and shore anglers by in large out fished those on area lakes. 
Walleye, northern pike and channel catfish were caught from all areas of the river including Otter and Campbell lakes. 
Lake Allie was also productive for some, with a few limits of smaller walleye checked. 
Officer Oberg also spent a lot of his time educating boaters and anglers on Aquatic Invasive Species laws at public accesses in the area. 
Unfortunately, CO Oberg had to remind several boaters to remove their plug while transporting their boats. 
Enforcement action was taken for fail to remove drain plug, fail to drain water from live well, transport live fish, fishing without a license, no type IV PFD, and youth ATV violations.

Question of the week
From the DNR

Q: With the water levels low in my lake this year, are there any rules on how far out I can put my dock?

A: Docks should only be long enough for their intended purpose – typically to get to deep enough water for navigation, or about four feet of depth.

The main rules to remember when extending docks are that a person cannot install a dock that obstructs navigation or creates a water safety hazard.

For more information about docks and access in public waters, go to: http://go.usa.gov/VD7.