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What DNR Fisheries Technicians Do When Winter Comes
December 13, 2007
Todd Somers is a Department of Natural Resources fisheries technician supervisor for the Lake Erie Management Unit. When asked what a fisheries technician does, Somers will say the primary job duties include surveying lakes and streams, fish tagging, performing stream rehabilitation and habitat enhancement work and conducting egg takes.
All important tasks, which are performed during busy spring, summer and fall seasons, when the technicians are outdoors, working hard to ensure that Michigan waters continue to have an abundant supply of healthy fish.
But with the onset of winter, some may wonder what a fisheries technician does when the lakes and streams are frozen.
According to Somers, the most important task that must be completed during the winter months is to build and repair all the netting gear, which includes trap nets, gill nets, fyke nets, minnow seines and trawls.
"Since we use a variety of entrapment gear, the nets need to be in the best working condition to be effective," said Somers. "If the nets have holes or frayed ropes from muskrats, beavers, turtles or from everyday wear, we must spend the time to repair them in order for them to be effective at catching fish."
Most fisheries management units have dozens of nets that need to be checked every winter. At Bay City, for instance, the inventory includes 61 fyke nets, 26 gill nets and 22 trap nets.
According to Chris Schelb, a fisheries technician supervisor for the Southern Lake Management Unit, it takes at least a couple of employees approximately three weeks to go through all those nets depending on how severe the damage.
"But repairing a net is much easier than building one," said Schelb. "It takes four fisheries technicians one full week to build a new trap net from scratch."
Another major task performed during the winter months is the processing of biological data collected during the surveying season.
This process requires the technician to prepare the fish scales, spines, fin rays and otoliths, (a minute calcareous particle found in the fish's inner ear) for aging.
"Depending on the number of surveys we conducted throughout the spring and summer, the number of samples to be processed could be anywhere from a few hundred to several thousand," Somers said.
The process begins at the lake with the collection of a sample, which involves either cutting the first four dorsal spines of the fish or taking a knife and scraping off a small number of scales and placing them in an envelope for record keeping and drying.
"If the samples are not properly dried, they have a tendency to mold and rot, since they usually are wet when placed into the envelope," said Somers.
Back in the lab, a technician uses one of two principle methods for aging fish. In the first method, approximately eight to 12 scales are placed on an acetate slide face down, covered by another acetate slide and pressed together using a hand roller press. Once the slides have passed through the roller, the scales leave their impression on the acetate slide for viewing. The slides then are viewed under a microfiche reader.
"The scale impression is enlarged on the microfiche screen so we can age the fish by counting the growth rings, which are very similar to tree growth rings," Somers said.
Fish spine and fin rays are processed a little differently than scales. The spine or fin ray sample needs to be cross-sectioned using a high-speed dremel tool. A very thin disk-like section is cut from the fin. The section then is placed under a dissecting scope to view and determine the age, again by looking at growth rings.
"Reading an otolith is one of the more time-consuming methods of aging, but one of the most accurate," Schelb said.
The usual method for aging an otolith, Schelb explained, is to crack it in half, brown it using an open flame to help provide some coloring, mount it in clay for stability, then look at the growth rings present.
Once the aging process is complete, the data is entered into a statewide survey computer database for record keeping. The information will allow a fisheries biologist the needed information to make management decisions.
Another important task during the winter months is to overhaul all the motors and workboats and fabricate new equipment. The outboard motors are winterized and any minor damage to the boat's hull or propeller is repaired. All boat trailer bearings are inspected and replaced if needed.
But the technicians also will check and repair all of the generators, pumps, hand nets, electrofishing equipment and pond rearing screens.
"Without proper working equipment, we wouldn't be able to complete our spring and summer work on the lakes or streams we survey," Somers said.
On occasion, fisheries technician are asked to provide assistance to other DNR divisions, such as helping the Wildlife Division carry out winter population surveys on white-tailed deer and elk.
Technicians also assist with the report-writing process from time to time on lakes or streams. Because the technicians routinely work on surveys without a biologist present, they often can add firsthand knowledge and observations, which adds validity to the report and contributes to the best method of management.
"By the time we have completed all these tasks," Somers said, "we have been in the office too long and we're ready to get back out on the water to start the process all over again."
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