SHEBOYGAN, Wis. -- Try to imagine Lake Michigan in the 18th century.
Before man-made channels eased the way for transoceanic shipping, before aquatic invasive species flooded in, before byproducts of the industrial revolution began to pollute its waters.
From the records available, the Big Pond's ecosystem was dominated by one top predator, the lake trout.
More than a dozen cool-water species such as walleye and northern pike were associated with bays and tributaries.
And further down the food chain, at least seven species of ciscos were known to exist.
It would be unwise to dismiss the smaller fish as mere food for bigger species. The ciscos also helped distribute energy from shallow to deep waters.
In fact one of them -- the lake herring, known to scientists as Coregonus artedi -- was the most abundant species in each of the Great Lakes, according to scientists.
The lake herring also was one of the most, if not the most, important commercially-caught fish species in Lake Michigan through the 19th century.
But populations of the ciscoes generally collapsed during the middle of the 20th century because of overfishing, interactions with invasive species such as alewife and rainbow smelt and loss of spawning and rearing habitat, according to research cited in "Ciscoes of the Laurentian Great Lakes and Lake Nipigon," by the Great Lakes Fishery Commission.
Five of the ciscos are now completely gone from Lake Michigan. Only the bloater chub and the lake herring remain.
And the population of lake herring, once the most abundant fish in the lake, has been reduced to extremely low levels, according to researchers.
As has been reported by the U.S. Geological Survey for the last several years, the prey fish biomass in Lake Michigan is at record low levels, largely due to the food and energy filtering impacts of invasive quagga mussels.
The population of alewife, the invasive fish that became the primary forage fish in the lake after the decline of the ciscos, is the lowest seen since bottom trawl studies were initiated in the 1970s.
The current state of Lake Michigan presents a challenge and, some think, an opportunity.
What can be done to build the fishery?
There is no appetite among state or federal agencies to stock alewife, an invasive species.
But a proposal is afloat to restore lake herring in Lake Michigan.
Chuck Bronte of the U.S. Fish and Wildlife Service presented an update on the idea in early December at a meeting of the Wisconsin Federation of Great Lakes Sport Fishing Clubs.
The concept of lake herring restoration began taking shape in 2013 with the formation of a task group.
Bronte said Great Lakes fishery managers had expressed interest in reestablishing a native forage base consisting of various forms and species of ciscos.
Since it operates a national fish hatchery system to assist with recovery of threatened or endangered species or to restore native species before they become threatened or endangered, USFWS staff has been involved with the task group from the beginning.
Lake herring historically spawned throughout the lake, Bronte said, including in rivers and in deep water.
The goals of a lake herring restoration would be to help feed trout and salmon and diversify the forage base by boosting numbers of a native fish.
Lake herring are still found in good numbers in Lake Superior but are extremely low in Lake Michigan, according to researchers.
Since the original genetic strain is still available in the Great Lakes, it could be feasible to obtain enough brood fish or eggs to raise fish in the hatchery system and stock into the lake.
Hypothetically, Bronte said a higher lake herring population could help improve several issues now seen in the lake.
In addition to bolstering the forage base, lake herring could also help transfer energy from offshore to nearshore through egg deposition.
And lake herring are more suited to the zooplankton community now found in Lake Michigan than either alewife or smelt, Bronte said.
The idea of lake herring restoration is progressing slowly, however.
State agencies around Lake Michigan have yet to endorse the concept.
The U.S. Fish and Wildlife Service requires the approval of states, Bronte said, before it proceeds with any stocking plan.
And scientists from the region have yet to agree on a lake herring strain or strains to use in any restoration effort.
One project has started, however: The Little Traverse Bay Band of Odawa Indians in Michigan is conducting a stocking experiment with lake herring eggs obtained from Grand Traverse Bay.
And in Lake Huron, lake herring have been stocked for the last two years in Saginaw Bay.
Fisheries researchers and managers will be watching closely to see the results of the work done by the band and in Lake Huron.
In the meantime, the Lake Michigan Committee is scheduled to consider a white paper on lake herring restoration at its meeting in March.
And the Lake Michigan Fisheries Forum will likely add a presentation on lake herring restoration to its spring meeting, said Titus Seilheimer, forum moderator.
Even the most ambitious stocking program is unlikely to restore lake herring to their previous abundance in Lake Michigan.
But if a careful, science-based restoration effort of this native species could even partially fill the void in the lake's food web, it would be good.
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