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By Lynne Weinberg
Native Paddlefish Return to Restored Habitat at Emiquon
Last December researchers at Emiquon celebrated the discovery of a well-nourished American paddlefish. Paddlefish need wetlands to thrive, and the appearance of that healthy fish (and two others to date) showed that the restoration of Emiquon’s wetlands is succeeding.
One of the oldest fishes on earth, the paddlefish has lived in the Illinois River basin for 300-400 million years and was here long before the dinosaurs. Scientists classify it as both ancient and primitive. It looks every bit the part: a long snout (rostrum) that resembles a canoe paddle and comprises one-third of its body length, a deeply forked tail and a skeleton that is almost entirely cartilage instead of bone. Sometimes called “freshwater whales,” paddlefish can grow up to seven feet long and nearly 200 pounds. They find their food—tiny, drifting zooplankton and insect larvae—with their long snouts, which, remarkably, detect motion through electroreception.
In the early twentieth century, the Illinois River basin boasted the largest freshwater fishery and mussel stream per mile in the nation. Waterfowl also were plentiful. Around 1920, to make way for crops, farmers began draining the wetlands. Overfishing and municipal and industrial waste soon degraded the river basin. Wildlife numbers and biodiversity plummeted. Paddlefish in particular were overfished because of their prized caviar.
In 2001, TNC purchased 7,800 acres of farmland along the river and in 2007 began to restore much of it to wetlands. When the water returned, so did many species. For example, within a few years, the numbers of duck species using Emiquon were breaking records with peak one-day waterfowl numbers exceeding 200,000.
Rebuild it and They Will Spawn
To survive the winter, paddlefish require water that is slower moving and warmer than that of the Illinois River. The rest of the year, they need zooplankton and insect larvae to feed on, gravel beds for laying and fertilizing eggs, and vegetation to shelter their young. In 2016, TNC installed a structure that restores seasonal exchanges of water between the wetlands and the river, which further improves the habitat paddlefish need to thrive. The structure contains two gated, concrete pathways (culverts) and water-sampling bays for monitoring water quality and the movements of plants and animals. Researchers use nets to catch some of the fish as they move into and out of Emiquon. They also conduct sampling in the lake—which is how they discovered the paddlefish
But just how did paddlefish find their way back to the preserve? Doug Blodgett, director of river conservation at TNC’s Illinois Rivers Program, gives four possibilities. The most likely would be through the culverts or over the levee in flood years. But they could have been released into Emiquon by fishers or even pelicans, which can carry fish in pouches on their bills.
“By restoring the habitat needed by the paddlefish, we are helping hundreds of other species to flourish. Not just rare or threatened species are benefiting—people are, too,” Doug told me, along with a group of TNC visitors, on a blustery March afternoon. Bald eagles hovered overhead, keeping an eye on their nearby nest and on the human observers. On one side of the levee, the Illinois River roared by, and on the other the wetlands were blanketed by thousands of snow geese and swans. Once again, Emiquon is home to some of the best fishing and duck-hunting in Illinois.
Fossil remains show that six species of paddlefish have existed, most in the Mississippi River basin, of which the Illinois River is part. Four are extinct, and another, the Chinese paddlefish found in the Yangtze River basin, is critically endangered.
“That leaves our American paddlefish,” Doug said. “We’re compiling a body of knowledge regarding habitat restoration that will be used not just at Emiquon, but in river basins and wetlands around the world.”