A tiny, olive-brown minnow that lives in swampy water in the Northwest United States has made a big comeback. The fish was on the brink of going extinct, 20 years ago, when the U.S. government added it to its Endangered Species List. That listing gave the fish extra protection from human activities that could have further harmed its chance of survival. The inclusion also focused attention on the fish and society’s need to save it. With the help of scientists, all of these actions now appear to have given the little species the boost it needed.
On Feb. 4, the U.S. government formally announced it planned to remove the Oregon chub from its Endangered Species List. This minnow would be the first living fish to be removed. (Other species have been removed from the list, but usually because they became extinct.)
The Oregon chub isn’t big or showy. At about 7.5 centimeters (3 inches) long, even the biggest of these fish can fit into the palm of your hand. Named after their home state of Oregon, they used to fill the muddy marshes of a valley created by the Willamette River.
But farmers drained water from much of the valley to make way for planting. This reduced the muddy waters available to the chub. In addition, communities released “foreign” (non-native) game fish into area rivers. This gave anglers popular fish to catch, such as bass, bluegills and bullhead trout. But those game fish fattened up by dining on the chub. By the early 1990s, the Oregon chub population had fallen to fewer than 1,000 fish, a miniscule number.
Biologists decided the chub needed protection and petitioned the U.S. government to add it to the Endangered Species List. In 1993, the U.S. Fish & Wildlife Service did that. Soon after, researchers stepped in to help. The evidence of their success: The most recent census finds that there are some 150,000 Oregon chub swimming in area waterways.
Recovery started with ‘chub in a tub’
To help the little fish recover, scientists needed to protect the chub from those introduced game fish that had become its predators. They also needed to give the chub more swampy habitat.
Their first solution was nicknamed “chub in a tub.” Researchers moved some of the struggling chub into shallow, newly dug ponds on farms and other lands. Here the chub could live without getting eaten by other fish. Each pond was about 2 meters (about 6 feet) deep and took up about as much land as a house. Planted cattails lined its edges. These plants offered places for chub to hide from the birds that also eat them.
Biologist Brian Bangs of the Oregon Department of Fish and Wildlife in Corvallis spent years checking on the chub to see whether their numbers were growing. At times, the task could seem downright dangerous. The reason: Chub habitat can be like quicksand, Bangs notes. It will suck you right in.
“I was stuck in the mud for at least 40 minutes one time,” he recalls. “I was up to my waist in oatmeal-consistency mud, just wiggling back and forth and trying to get myself out.”
He and others made the effort to catch the fish in traps and count them.
In all, scientists set traps in 1,000 different places where they thought chub might be living. The fish turned up in 80 of those spots.
“Finding them wasn’t always the easiest thing to do,” observes biologist Paul Scheerer of the Oregon Department of Fish and Wildlife. “It’s a bit of a needle in a haystack.” And he should know. Scheerer has been studying the chub for 22 years. In most months, he notes, “they’re very difficult to see. Most people who walk up to one of these swamps wouldn’t even know they were here.”
Bangs and Scheerer say Oregon chub are so small that not many people know or care about them. Still, these fish do play an important role in nature.
“Oregon chub eat mosquitoes, but that certainly isn’t their only function,” Bangs said. “They’re a food source for a lot of things people do care about like trout, birds and mammals.”
Altogether, scientists have introduced Oregon chub into 21 new ponds and swamps. Some of those scientists, like Scheerer and Bangs, worked for state agencies. In addition, many landowners opened up their property to chub tubs or promised to protect local waterways. Over the past 20 years, the cooperation of these groups has helped chub populations recover.
Indeed, “this extraordinary partnership that includes federal and state agencies, landowners and others stakeholders has served as a model of how we can use the Endangered Species Act as a tool to bring a species back from the brink of extinction,” says Sally Jewell. She directs the U.S. Department of the Interior. The Fish & Wildlife Service is one of its agencies.
Adds Dan Ashe, who heads the U.S. Fish and Wildlife Service: The cooperation to save the chub “is an excellent example of how the Endangered Species Act is intended to function — partners working together to recover an endangered species.”
census An official count or survey of a population.
endangered An adjective used to describe species at risk of going extinct.
predator (adjective: predatory) A creature that preys on other animals for most or all of its food.
quicksand A plot of loose sand that is mixed with water. The combination creates a soft surface. Anything that lands on it starts to slide below. Movement can increase the likelihood that something on the surface will become engulfed.
species A group of similar organisms capable of producing offspring that can survive and reproduce.
swamp A type of low-lying wetland where water collects. It tends to sustain more trees and woody species than a marsh.