Invasive gobies staking out new territory Great Lakes Echo (2/12) An uninvited outsider is rapidly showing up in new freshwater territory in Wisconsin—and a recent scientific study indicates the increasing impact the small fish.
Commentary: Campaign for the birds Michigan Radio (10/18) There are hundreds of dead birds washing ashore in Michigan due to an outbreak of botulism caused, in part, by invasive species; I wish politicians would stop talking about imaginary birds and take this issue on, before it’s too late.
The round goby (Neogobius melanostomus) is a non-native fish that is causing substantial ecological and economic impacts on Great Lakes fisheries. Originating from central Eurasia, the round goby and the closely related tubenose goby were first detected in the St. Clair River in 1990, introduced via contaminated ballast water of transoceanic vessels.
While tubenose goby populations have remained relatively small, a rapid range expansion of round goby has occurred throughout the Great Lakes since initial introduction via ballast water. Several physiological and behavioral traits have allowed this bottom-dwelling fish to thrive in the Great Lakes ecosystem: aggressive behavior, voracious feeding habits, and their ability to detect water movement, allowing them to feed in complete darkness.
Environmental impact: round gobies have been linked to declines in populations of other bottom-dwelling Great Lakes native fish like mottled sculpin, logperch, and darters. The round goby competes with these species for food and habitat, especially spawning sites. Other competitive advantages held by the round goby over natives are their ability to survive in degraded water conditions, spawn more frequently over a longer period, reproduce rapidly, and guard nests from predation of their eggs. Gobies consume the eggs and fry of lake trout, posing a substantial threat to this economically and ecologically valuable native fishery. Round gobies also are troublesome to recreational anglers given their ability to "steal" bait, replacing the catch of desired species such as walleye.
Round gobies generally prefer nearshore habitats of rock, sand, cobble, gravel, and/or submerged aquatic vegetation (e.g., macrophytes), but are also invading offshore reefs where they are an increasing source of prey for burbot, lake trout, and lake whitefish. Because round gobies contain less energy upon consumption than native prey, and ingest toxic substances through consumption of large quantities of zebra and quagga mussels, this is problematic for these predator fish, which are also popular sport fish--causing an increase in human health risks for those anglers who eat their catch on a regular basis.
Photo credit: David Jude, University of Michigan SNRE, Center for Great Lake and Aquatic Sciences
Use of electrical barriers to deter movement of round goby (2001) American Fisheries Society Symposium (Vol. 26) Researchers performed both laboratory trials and field tests to determine the effectiveness of a series of electric cables in preventing the movement of adult round goby among watersheds in the Great Lakes region.
What Will Round Gobies Do to Great Lakes Streams? (Web video, 2011) University of Wisconsin Sea Grant After sampling round gobies in 26 Wisconsin streams and observing no devastating ecosystem impacts, University of Wisconsin researchers are continuing stream assessments throughout the state to gain a deeper understanding of the potential impacts (or lack thereof) of this Great Lakes invader.