Experts perplexed after prehistoric fish makes unexpected comeback: 'We don't necessarily know for sure'

The paddlefish, a species that dates back to when dinosaurs roamed the Earth, is making a comeback in Minnesota.

A three-year survey by the state's Department of Natural Resources showed a surprisingly high number of the boneless fish, which date back 125 million years. Minnesota Public Radio reports that more than 80 paddlefish were counted in the Minnesota River during the project, a massive increase from the last time these fish were surveyed.

"In the Minnesota River, DNR fisheries staff had only captured one paddlefish in a survey prior to 2016," Anthony Sindt of the Minnesota DNR told MPR News.

Native to the Mississippi River basin, paddlefish can be up to 7 feet long and weigh up to 200 pounds. They're most known for their long, paddle-shaped snout, called a rostrum, which can be up to one-third of their body length. Their large mouths have no teeth, and they instead filter-feed on zooplankton.

Paddlefish are classified as a threatened species in Minnesota, meaning that they're considered likely to become endangered in the foreseeable future. Nationally, the U.S. Fish & Wildlife Service notes that many states list the paddlefish as endangered or threatened, and that its population has been declining since around 1900.

A variety of factors led to that population decline, including overfishing, water quality, and a decline in their natural habitat. They have also been difficult for the DNR to track because the agency prioritizes monitoring of sports fish, such as walleye and pike.

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"So for a long time, it was thought that the paddlefish population may not be very large or as big as it once was," Sindt told MPR News. "But, we don't necessarily know for sure if that's true."

Officials did say that statewide efforts to improve water quality and remove dams could be helping paddlefish numbers grow.

Saving threatened and endangered species can be vital to ecosystems, as the extinction of animals can throw off the delicate balance that wildlife have depended on for generations. Efforts like those in Minnesota, and elsewhere, prove that this is possible.

In Oregon, river restoration has helped salmon return to an area once devastated by wildfire. The California red-legged frog, also a threatened species, has shown remarkable gains in a wetland preserve. And in France, the government has forced many fishing boats to stay docked, in an attempt to protect dolphins, while covering a significant portion of anglers' revenue.