Invaders on the move: Round Goby and Quagga Mussel
Some well-known aquatic invaders are showing up in new places. You can help to track their spread if you know where to look and how to report what you find.
Aquatic invaders make headlines on a daily basis, but did you know that you can play a role in tracking their spread? With 94,000 square miles of water in the Great Lakes Basin there is plenty of room for invaders to hide. Some familiar pests are making their way into new habitats, and others that have been here for a long time have gone largely unnoticed.
The following information is provided by the Great Lakes Aquatic Nonindigenous Species Information System (GLANSIS) and Michigan State University Extension. Once on the GLANSIS site, click on the species names for more information and a detailed map of all known sightings in the Great Lakes Basin. If you find one of these invaders in an area that is not on the map, take photographs showing key features of the species and fill in this online report. Once the identification is verified, your finding will be added to the map and become available to researchers around the world.
How to ID: The goby is a small bottom-dwelling fish that resembles native sculpin. Unlike sculpin, gobies have fused pelvic fins and a black spot at the base of the spiny dorsal fin.
Where they are: Round gobies are widespread in all Great Lakes other than Lake Superior. They are very common in river mouth areas, shallow bays, and connecting waters.
Where they might be: Gobies have been making their way up streams and rivers that feed the Great Lakes. Look for gobies in rocks around bridge abutments. They are easy to catch on a small hook and worm. Other areas to watch include large inland lakes with heavy boating traffic and ports on Lake Superior.
What is the risk?
A study of round goby invasion in Wisconsin streams suggests that impacts to stream insects and fish may not be severe. However, the effects of gobies in high-quality trout streams of Michigan have never been studied. Round gobies are well-known egg predators and are now invading salmon and trout spawning areas.
How to ID: The quagga mussel is similar to the closely-related zebra mussel. The quagga mussel has a convex edge on its ventral side while the zebra mussel has a flat edge. To check which species you have, place the ventral side of the shell on a table or other flat surface. A zebra mussel will stay upright and a quagga will topple over.
Where they are: Quagga mussels have displaced zebra mussels in many Great Lakes habitats and are extremely abundant in Lake Michigan, northern Lake Huron, and Lake Erie. They outcompete zebra mussels in deep, cold water with a soft or sandy bottom.
Where they might be: Zebra mussels have spread to many inland lakes, but quagga mussels have not. Both species can be transported by boaters and have a planktonic life stage that can be unknowingly carried in bilge water or livewells. Look for quagga mussels in lakes with heavy boating traffic. Although quaggas do not necessarily attach themselves to hard substrate like zebra mussels do, both species are commonly found attached to rocks and dock pilings.
What is the risk?
Deep, clear inland lakes may be more vulnerable to quagga mussels than zebra mussels. Quagga mussels might go unnoticed in lakes that have already been invaded by zebra mussels because the two species look so similar.