Non-natives key

MARQUETTE – This week, with ice beginning to melt along Great Lakes shorelines, and tributary rivers and streams opening up, anglers from Skanee to Flat Rock to Kalamazoo are eager for springtime opportunities to hook a trout or salmon for the dinner table.

But what some anglers may not know is many of Michigan’s familiar trout and salmon species prized as Great Lakes table fare today were not fish originally native to the freshwater lakes, but instead are the product of efforts to introduce species to the region from other areas.

Among coho, chinook, Atlantic and pink salmon to rainbow and brown trout and the hybrid splake, none of these fish were originally found within the Great Lakes.

The first efforts to introduce new trout and salmon species began roughly a generation after the Industrial Revolution ended in America, a time when brook and lake trout -the only native Great Lakes salmonids- were being depleted, along with other fish species.

“By 1870, many of our fish populations were in serious decline particularly near populated areas or ports,” said Gary Whelan, a program manager for the Michigan Department of Natural Resources Fisheries Division in Lansing. “This was from over harvest of accessible fish populations, construction of barriers on our tributary streams that eliminated spawning habitat, severe water quality issues from sewage, industrial and logging wastes, and landscape changes in land use from wholesale logging and urbanization.”

Whelan said so many areas had declining fisheries that the public demanded changes which lead to formation of the U.S. Fish Commission in 1870 and the Michigan Fish Commission in 1873. Those bodies were focused on trying to improve fisheries any way they could, which was mainly through fish stocking to replace lost native species.

“They were well aware of the habitat destruction and overfishing, but had no legal instruments to deal with it,” Whelan said.

Various fish species were chosen for stocking, including lake whitefish, lake sturgeon, American shad, carp and American eels for their food value. Rainbow, brown and brook trout, along with chinook and Atlantic salmon were also selected.

“New European immigrants wanted fish they were familiar from their home countries such as eels, brown trout and carp so a lot of fish were brought in from Europe to meet this need,” Whelan said.

Other species found to be ‘good’ commercial and sport species were brought in from the eastern (Atlantic salmon) and western (chinook salmon and rainbow trout) parts of the country to replace lost native fish species, Whelan said.

Atlantic and chinook salmon were introduced in 1874 and stocked for about a decade, with some returns. Rainbow trout (steelhead) were first brought to the Great Lakes from California in 1876. Brown trout were introduced in 1884 from strains found in Germany.

Of these early introductions, rainbow trout was the only species to prosper.

“More recent stocking efforts date back to the 1960s-1970s, following the collapse of lake trout populations and the invasion by alewives and rainbow smelt,” according to the Great Lakes Environmental Assessment and Mapping Project. “Chinook and coho salmon were specifically introduced to control alewives and to create a sport fishery.”

Sea lamprey native to the Atlantic Ocean, which eat body fluids of fish they attach themselves to, were first found in Lake Ontario in 1830, according to the Great Lakes Fishery Commission. They were prevented from reaching the other Great Lakes because of the natural barrier of Niagara Falls.

“However, when the Welland Canal, constructed to bypass the falls, was deepened in 1919, sea lampreys gained access to the rest of the Great Lakes,” according to Minnesota Sea Grant. “By 1938, they had invaded all of the Great Lakes.”

Lampreys contributed significantly to the decline of lake trout populations.

Alewives also arrived through the Welland Canal expansions. Members of the herring family, alewives eat algae and small crustaceans and could compete better for these foods than other fish. Alewives also preyed on larval stage fish and contain an enzyme that causes thiamine deficiencies in fish that eat them and poor survival rates for the young of those predators, including lake trout, Whelan said.

“In combination with habitat degradation, high alewife consumption and over harvest drove them (lake trout) to near extirpation, and likely affected a broad range of larger bodied fish,” Whelan said. “Sea lamprey helped to reduce predator levels which gave alewives a clear opening to greatly expand their numbers.”

By 1955, lake trout had almost disappeared from most of the Great Lakes, except for small populations in Lake Superior.

“These fish, along with fish moved from the Great Lakes to other waters during the period from 1880-1920, became key broodstock fish for rehabilitation efforts that included stocking, sea lamprey control, and harvest management, and continue today,” Whelan said.

Meanwhile, alewife populations exploded.

“By the early 1960s, between 90 percent to 99 percent of all fish biomass in the lakes Michigan and Huron were alewives and they washed up onshore by the truckload,” Whelan said. “Chinook and coho salmon were introduced to control alewives and provide a sport fishery.”

Whelan said the salmon are capable of driving alewife numbers down to near extinction when the predators are in high numbers and severe winters occur together.

“This is what happened in Lake Huron by 2005 and now it is very hard to find alewives in Lake Huron,” Whelan said. “They are still present in Lake Michigan, but their numbers are very low in comparison to historic numbers. Alewives were never common in Lake Superior as the water temperatures are too cold for them to build large populations.”

The Ontario Ministry of Natural Resources said coho salmon were first introduced in Lake Erie in 1933. In 1966, coho were introduced to the Great Lakes from Oregon to balance the predator-prey relationship, with introductions continuing into the 1990s. Chinook salmon were reintroduced in 1967 under the program that continues today. Atlantic salmon were reintroduced in the 1970s from Maine, Whelan said.

Splake are a hatchery hybrid between brook – or speckled – trout and lake trout introduced to the lakes in the 1950s in Ontario. In 1956, 21,000 pink salmon were accidentally introduced into the Current River in Ontario, resulting today in small self-sustaining populations in lakes Superior and Huron, Whelan said.

Michigan Sea Grant said recreation and commercial fisheries remain a vital part of the state’s heritage, valued in excess of $4 billion to $7 billion each year.

Jeff Gunderson of Minnesota Sea Grant said Lake Michigan rebounded from the alewife explosion and lake trout decimation by sea lampreys, through the salmon introductions from the west.

“Lake Ontario has undergone a similar metamorphosis and now has a first-rate trout and salmon fishery,” Gunderson wrote in a website article. “Lake Erie rebounded from its pollution problems and within 10 years transformed its reputation. It went from ‘dead’ to one of the top walleye lakes in the country.”

Lake Erie also has hatchery raised steelhead.

Whelan said Lake Michigan’s fishery today is dominated by chinook salmon (about 60 percent wild fish); rainbow trout (about 50 percent wild) and hatchery maintained coho salmon are also present.

Lake Huron has a mixed trout and salmon fishery with an increasing number of wild lake trout, hatchery and wild rainbow trout, mostly wild chinook salmon in the north part of the lake and hatchery raised Atlantic salmon. Whelan said pink salmon can occasionally be abundant, but also fluctuate wildly in number.

Today, Lake Superior is dominated by lake trout, which are self-sustaining.

“It is an excellent lake trout fishery and an important commercial lake whitefish fishery (all wild),” Whelan said. “There are stable and good populations of chinook and coho salmon, steelhead and localized walleye populations.”

That chinook salmon and steelhead population are a combination of wild and stocked fish. Coho and pink salmon in the lake are wild fish. The pink salmon numbers fluctuate, but are generally low, while stocking has provided localized populations of splake.

John Pepin can be reached at 906-228-2500, ext. 206. His email address is jpepin@miningjournal.net.