Each summer I spend a week teaching an intensive course in entomology at Ohio State’s Stone Lab on Gibraltar Island. Sometimes I have an evening free for fishing, and last week I cast worm after worm among rocks where I’d caught a few white bass in years past. I kept getting nibbles from fish, either small or wily, and they continued to nibble my worms off the hook. In semi-desperation I shifted to an artificial spinner and in no time I had hooked a 4-inch monster round goby.
The Round Goby is a big-headed, bug-eyed bottom feeder, subsisting on insects, worms, fish eggs and fry, and other aquatic animals. Adults average 4 to 8 inches long, and closely resemble native sculpins (with which they may compete).
The Round Goby is another in a growing list of exotic species (like Zebra Mussels) that have invaded the Great Lakes since the St. Lawrence Seaway opened fifty years ago. They apparently arrived in ships’ ballast, water that is pumped into a freighter’s hold to provide stability. Ocean-going ships that sail with freshwater ballast from Eurasia are required to flush their tanks with seawater while crossing the ocean. Most captains comply, but all it takes is one infested ship to start an invasion. Round Gobies were first discovered near Detroit in 1990 and now inhabit all the Great Lakes. They have made their way down the Illinois River nearly to the Mississippi and have been found in a few inland locations in northern Ohio.
What is the problem, aside from the potential competition with native fish? The Round Goby is so prolific that it has become the dominant small bottom-feeding fish in Lake Erie. The ecology of the Lake will change but we don’t know how, just yet. As bottom feeders, gobies will concentrate chemicals in their diet, and we may see another increase in levels of PCBs and other toxins in predators. Gobies comprise much of the diet of cormorants, and 90% of the diet of the endangered Lake Erie Water Snake.
Meanwhile, the take home message for now is: do not transport live fish from one body of water to another.
My own goby was hooked pretty well so I cast him/her/it further out into the lake as bait in hopes of a larger fish. This has worked for me in Vermont but I had no such luck in Lake Erie. So I set my goby free and hoped that a white bass or a water snake would find a meal.
For more information, see the USGS Goby Fact Sheet or the USDA Goby Invasive Species page.
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