2014-02-20 / Outdoors

DNR fisheries techs’ work continues even in winter


Mending trap nets is a big part of the off-season work for Michigan DNR fisheries technicians like Jacob McWethy, who works out of the Crystal Falls district field office. 
Photo courtesy DNR Mending trap nets is a big part of the off-season work for Michigan DNR fisheries technicians like Jacob McWethy, who works out of the Crystal Falls district field office. Photo courtesy DNR LANSING – Fisheries technicians are among the most visible Department of Natural Resources employees – spring, summer and fall – when they are out on the waterways, conducting surveys or working on habitat projects. But did you ever wonder what they do during the winter?

The work of Michigan DNR fisheries technicians continues well into the winter and includes vital equipment maintenance and data analysis.“We get that question all the time,” said Jacob McWethy, a fisheries technician who works in the northern Lake Michigan and western Lake Superior districts out of Crystal Falls.

The answer: They do plenty, finishing up the work they conducted during open-water season and making sure the gear is good to go for the next year.

For instance, fisheries technicians take fin samples from the fish they collect at lake and stream surveys, but they don’t work them up until the off-season.

To age the fish they’ve collected, the technicians take spines from the fins, cut a thin slice, and examine them under a microscope. The techs look for growth rings – similar to the rings on a tree – to determine a specimen’s age.

Last year, McWethy and his partner Jody Johnston collected specimens from 11 bodies of water.

“It takes about a week of aging to finish a survey for one lake,” McWethy said. “A stream survey only takes two days – we get considerably fewer fish. I’d say we’ll easily spend eight weeks on it this winter.”

That’s not the only data they collect.

McWethy said they’ll spend another week updating fishstocking records and more time entering temperature data they collected on bodies of water.

In early summer, the techs put temperature probes (thermistors, if you want to get technical) into all the bodies of water the crew plans to survey that season. The 6-inchlong, 1-inch-diameter devices take hourly temperature readings for the entire season, until they are collected in October.

“They’re wired to stumps or logs or, if there’s nothing there, we’ll even put a post in the water to hold them,” McWethy said. “We put them in water that’s deep enough that they’ll be covered all year, at least 3 feet. It tells you the monthly mean temperature and – if, for instance, it’s a trout stream – if the water is getting too warm to support brook trout or – in a lake – if it’s getting too warm for pike or walleye.

“We monitor the trend over time to see if it’s going up.”

Besides working with data, the crews put in a lot of time maintaining, repairing and improving their gear.

“We winterize all the boats, trailers, outboards and water pumps,” McWethy said. “It takes about two weeks to go through all our boats and gear. We refurbish them – do what needs to be done. We change the oil, change the plugs, check the trailer wiring and replace the bearings and paint or replace the floor of the boats. If there’s a crack in the boat, we’ll have it welded.”

Gill nets and fyke nets are marked with buoys, which must be maintained, too, but McWethy said since all of them were done last winter there aren’t a lot of buoys to work on this year. “It’s actually a blessing this year that we had so much ice,” he said, “as it lets us get caught up on other things.”

As spring approaches and the crews prepare to begin survey work, most of the DNR’s fisheries technicians are champing at the bit to get back out in the field.

Conducting surveys is “my favorite part of the job,” said McWethy, a 10-year veteran of the DNR Fisheries Division. “I get too see all kinds of fish. And when we get a complaint about fishing in a certain lake, we can find out what’s really going on there.”

Learn more about the state’s fisheries – including fish stocking, the new Aquatic Habitat Grant program at www.michigan.gov/ fishing.

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