Rearing Brown Trout at Oden Hatchery Begins With Egg Take

January 17, 2008

Visit any pier along the Lake Michigan shoreline in a couple months and you likely will see numerous hardy souls sitting on five-gallon buckets, bundled up against the cold, keeping a close eye on their fishing rods baited with spawn bags.

A few might be chucking spinners or spoons in an effort to generate a little body heat, and, if the winds aren't blowing too hard, you also might see a few boats trolling spoons in the shallows or around the pier heads.

It's likely each one of these anglers is after the same thing -- a fat, healthy, Great Lakes brown trout.

In the fall, as deer season approaches, many of these same anglers will be wading in the shallows of our state's larger inland lakes, such as Higgins Lake, using the same techniques. Only this time they will be after inland brown trout, brightly adorned with their spawning colors.

In either case, the fish these anglers seek started out several years earlier at one of the fish hatcheries operated by Michigan Department Natural Resources Fisheries Division.

Brown trout are reared at three of the six DNR-run fish production facilities. Harrietta (18 miles west of Cadillac) and Thompson (just west of Manistique) hatcheries rear browns for production (stocking in lakes and streams) while Oden (north of Petoskey) rears production fish and maintains brood fish for both brown trout and rainbow trout.

According to Ed Eisch, hatchery manager for the northern Lower Peninsula, it takes a minimum of three years for a brown trout to reach sexual maturity and many don't produce eggs or sperm until they are four years old, so hatchery personnel need to plan ahead when it comes to collecting future brood lots.

Egg takes are conducted every two weeks from late September to early February, depending on the strain of fish.

"An egg-take operation requires several people in order for it to run smoothly," said Eisch.
"Two people are needed to anaesthetize the fish (one for the males and one for the females), one is needed to strip the eggs from the females, one handles egg disinfection and one runs buckets back and forth between the raceways and the disinfection station."

Disinfection is necessary because captive, hatchery-reared trout are subject to a wide array of diseases.

Soon after fertilization the eggs are rinsed and covered with an antibiotic solution for one hour. The eggs then are rinsed again before they are covered with an iodine-based disinfectant to kill any pathogens that might be on the surface of the eggs.

"This may sound like a lot to go through, but without these precautions, it is much more likely that the fish will suffer disease outbreaks," Eisch said.

In fact, long before the first egg of the season is squeezed out, Eisch said every single adult brood fish is subjected to both antibiotic and vaccine injections to help ward off some of the more common (and more deadly) fish diseases.

Every employee at the Oden State Fish Hatchery takes the production of quality eggs and fish very personally.

"They work hard all year with an eye toward one goal -- providing high-quality fishing opportunities for Michigan's angling public," Eisch said.

When the new Oden facility opened in 2002, there was a steep learning curve to climb. The constant, lower water temperature made attaining desired fish size a challenge. The lower temperatures also resulted in decreased egg size.

Hatchery personnel also had to work through some initial fish disease issues, but, after going through several rearing and egg-production cycles, the quality of the eggs and fish coming from Oden has improved significantly.

"The fish health issues were especially frustrating because the disease treatments were very time consuming for the fish culturists," said Oden Hatchery Biologist Dan Sampson. "But the high quality of the eggs taken this fall and winter shows these efforts have been worthwhile."

The DNR fisheries technicians, who spend the bulk of the year working in the hatchery caring for the fish, also get to see first-hand the fruits of their labor.

Starting in late March, they load the trucks with yearling brown and rainbow trout and deliver them to lakes and streams from the southern Lower Peninsula to the west end of the U.P. In 2007, the fish production section of the DNR Fisheries Division planted more than 1.1 million brown trout at more than 370 locations in 58 counties. The year's final tally for rainbow trout exceeded 2.1 million fish, which the DNR planted at more than 220 locations in 58 counties.

"People are always happy to see the stocking trucks show up," said Fisheries Technician Jason Swan. "It isn't uncommon for drivers to honk and give us the thumbs-up when they pass our stocking trucks on the highway.

"Because we produce eggs and rear the fish all the way to stocking size, it's especially satisfying when you pull into a Great Lakes stocking site and see a parking lot full of trucks with empty boat trailers or a pier lined with anglers going after fish stocked in previous years."

Eisch said raising both brood fish and production fish requires the coordinated efforts of various disciplines at the hatchery.

The technicians take care of the daily fish husbandry duties, which are coordinated by the hatchery biologist. All hatchery operations are reliant on properly functioning mechanical systems, and the maintenance staff works hard to ensure these systems work properly. Finally, the administrative staff provides the support necessary to make it all happen.

"The rewarding nature of these jobs is usually evident, but especially so during the egg-take and fish-stocking seasons," Eisch said.

The state's six hatcheries are open to the public and most provide guided tours and educational programs. To learn more about the hatcheries, visit the DNR Web site at www.michigan.gov/dnr and click on the Fishing section.