Minnesota fish threatened by foreign invader

Valerie Schlegel

With the opening of fishing season upon us, the dreaded round goby may be invading Minnesota lakes. But the University-funded Minnesota Sea Grant is prepared, with a program to help rid area lakes of the alien fish.
The round goby can be identified by its raised, frog-like eyes and slate gray coloring. A native of the Black and Caspian seas, the round goby is new to this area; it was first discovered in Lake Superior last July. The invader was probably introduced to the Great Lakes sometime before 1990. The fish likely came to the great lakes in the tanks of large ships that take on water to improve balance before transoceanic trips. The round goby has established itself in every one of the Great Lakes except Lake Ontario.
The round goby threatens native fish by destroying their habitat. “Basically, the round goby can out-compete the native fish,” said Doug Jensen, Minnesota Sea Grant Exotic Species Information Coordinator. An aggressive fish that can steal bait from hooks, the round goby’s temperament allows it to dominate prime spawning sites and make them unavailable to native fish. The round goby also feeds on the eggs and young of native fish.
Experience shows that the expansion of the round goby could threaten sport and commercial fishing in Minnesota. “The round goby poses a threat based on other places” where it has taken up residence, Jensen said. In Detroit, fishers have reported catching only round gobies when fishing for walleye.
The Minnesota Sea Grant, a federal, state and University program with funding from all three sources, is trying to stop the spread of the round goby by offering free “Round Goby WATCH” cards identifying the fish. The card features a picture of the round goby, and instructs fishers who find round gobies to kill them on sight and immediately contact an agency listed on the card.
The Minnesota Sea Grant “is a statewide program which sponsors researchers looking into Lake Superior and Minnesota water issues,” said Marie Sales, acting communications coordinator for Sea Grant. “In addition to sponsoring researchers, we make sure the information gets to the public through education,” she said.
One-hundred thousand “Round Goby WATCH” cards have been produced for distribution to people who fish. The cards can be obtained by contacting the Minnesota Sea Grant office.