The corner tank in the corridor behind the Illinois Lakes and Rivers gallery at the Shedd Aquarium isn’t pretty, but to the 260 sturgeon inside it’s home. When placed in the concrete tub 14 months ago, the fish were mere fingerlings, about four inches long; now they’re two feet long or longer, with dorsal spikes you could cut your finger on and powerful mouths that can suck a round goby out from under a rock–which is just the job that Roger Klocek, the aquarium’s senior conservation biologist, raised them to do. Lucky for the gobies of Lake Michigan, however, the laboratory-raised sturgeon will not be reporting for duty as planned.
Best of Chicago voting is live now. Vote for your favorites »
The only positive thing to be said for the gobies is that they eat zebra mussels, another exotic species introduced into the lake via the same route in the late 80s. A single goby can reportedly eat 78 zebra mussels a day. Unfortunately, that isn’t enough to cancel out the damage either species is doing. Like gobies, zebra mussels breed like roaches and eat like Pac Man–specifically, they strain the water clean of the phytoplankton that fish larvae need to grow into fingerlings. The Shedd has gobies on exhibit in the exotic tank in the Illinois Lakes and Rivers gallery, but no zebra mussels. “We can’t keep them alive,” Klocek says. “They eat so much, you can’t keep enough food in the water.”
Extrapolating from the size of catches recorded in the 19th century, scientists estimate that there were once 11 million sturgeon in Lake Michigan, but the population abruptly collapsed in the early 1870s due to overfishing and has yet to recover. Today there are fewer than 1,000 sturgeon in the lake.
If they’re unable to find water that tastes like home, spawning sturgeon will settle for the best conditions they can find. But all sturgeon migrate around the lake in a counterclockwise pattern, from northwest to northeast, which means that Klocek’s sturgeon would eventually end up in Michigan waters. “Our fish are not going to return to Wisconsin streams to spawn,” he says. “They’re going to wander the lake. And when they get there they’re gonna say, hey, the water’s pretty good, and there are other fish spawning here, so let’s spawn! They’ll probably interbreed with the Michigan fish, and you’re going to lose that genetic strain, which could be a bad thing 200 years from now when the populations are built back up to millions of sturgeon. We’ll have diluted the genetic diversity. This sounds very German, doesn’t it? I’m scaring myself.”
For the time being, Klocek’s guys aren’t going anywhere. The same goes for the zebra mussels and round gobies in the lake.
