The Michigan Department of Natural Resources has embarked on a cooperative project to restore the once-abundant lake sturgeon to several Lake Michigan tributaries.

"Lake sturgeon historically was one of the most abundant fish species in the Great Lakes and during the late 1800s and early 1900s it supported a valuable commercial fishery," said Ed Baker, fisheries research biologist at the DNR's Marquette State Fish Hatchery and Research Station.

But overharvest, dam construction, habitat destruction and pollution all have contributed to its near extinction, Baker said. Although commercial harvest has been prohibited in Michigan since 1929 and recreational harvest is limited, lake sturgeon abundance has not increased appreciably since 1900.

Lake sturgeon abundance in the Great Lakes, in fact, is estimated to be less than one percent of what it was in the late 1800s, and today the lake sturgeon is listed as a threatened species in Michigan.

In a cooperative effort to restore lake sturgeon populations in the Great Lakes, the Michigan DNR, Wisconsin DNR and the Little River Band of Ottawa Indians are working together to test the potential of using portable streamside hatcheries for this species.

"The streamside hatcheries, which are housed in custom-built trailers, are designed to raise lake sturgeon from the egg through the six-months-old fingerling stage," Baker said.

Two of the portable streamside hatcheries currently are located in the Upper Peninsula, one on the Cedar River and one on the Whitefish River. Both rivers once supported lake sturgeon spawning runs but recent survey data showed they now are absent from these rivers.

The reason for using streamside hatcheries instead of a more traditional hatchery is so the fish can be raised in ambient river water from the stream where they will be stocked.

The lake sturgeon is similar to salmon and steelhead in that they imprint to the river where they hatch and then return to their river of origin when they are mature and ready to spawn. Biologists generally agree this imprinting probably occurs at a very early age.

"Raising lake sturgeon in the streamside hatcheries using ambient river water will maximize the chances that the fish imprint and then return to the river to spawn in 20 years," Baker said. "This is important because it will reduce the chances of a stocked fish straying to other rivers and spawning with fish in existing populations. Protecting the genetics of the existing wild lake sturgeon populations is as important as restoring lake sturgeon in rivers where they formerly occurred."

Raising lake sturgeon in the streamside hatcheries presents some unique challenges. Site selection is an important step in the process. Water quality, site access and proximity to utilities also are important considerations, and the availability of a suitable egg source is critical.

The actual fish culture process begins with the collection of eggs from spawning fish in late April or early May. Eggs hatch quickly, within a few days, and the fish grow rapidly.

However, unlike trout and salmon which can be fed commercial fish food pellets, lake sturgeon must be fed natural foods. Live brine shrimp and frozen bloodworms keep the fish growing rapidly and by the time the fish are stocked in September they have grown to a length of six to eight inches.

Prior to stocking, the fish are tagged and some of the fish will have radio transmitters attached to allow researchers to monitor their movements. Evaluating habitat use, movement and survival are short-term goals of the evaluation but the real measure of the program's success will come 15 years from now when fish hopefully will return to the river to spawn.

"If we begin to see natural reproduction in these stocked rivers we'll be much closer to our goal of restoring lake sturgeon," Baker said, "and, if successful, lake sturgeon will once again become an important and well-known member of the Great Lakes fish community."