Stop the Spread-The Round Goby: Trout Unlimited Canada’s Stop the Spread campaign focuses on preventing the spread and impact of invasive species and pathogens that threaten Canada’s fisheries. There are a number of invasive species threatening Canada’s water. Meet an invasive that is impacting our native fish species and their habitat, the Round Goby.
The Round Goby is a bottom dwelling fish similar in appearance to the sculpin. The most notable difference is its single scallop-shaped pelvic fin, which acts as a suction cup allowing it to attach itself to rocky or pebbly bottom substrate. Adult females are often 80-100 mm in length with males 100-130 mm reaching at times a maximum of 250 mm. They have a full scaled body which is brownish or olive with dark brown spots. There is a single black spot on the rear of its first dorsal fin. Reproducing males have completely black bodies and fins.
Sources of Introduction:
Native to the Caspian Sea, northern Black Sea, Sea of Azov, and their tributaries, they were first discovered in North America in 1990 in the St. Clair River north of Windsor Ontario, likely originating from the ballast water of ships. Since then the Round Goby has spread to all five Great Lakes and many of their tributaries and has also been observed in some inland waters in Ontario (Lake Simcoe, Rice Lake along with the Trent and Otonabee rivers).
Impact to the Environment:
Literature indicates that the Round Goby can be found in large densities up to 100 individuals/m2. Gobies generally inhabit shallow areas of water (either fresh or brackish), but may also be found in open sandy areas. They have been known to overwinter in water as deep as 60 m. This invasive species are voracious feeders, feeding on insects as well as on eggs and young of native sport fish. They also feed on zebra mussels, another invasive species, with studies showing that a single goby can eat as many as 78 zebra mussels per day. However, outbreaks of botulism type E (a toxin accumulated in these mussels) have been observed in fish and fish-eating birds of the Great Lakes. Infected gobies show a change in behaviour which makes them easy prey to fish-eating birds. It is believed that this toxin is passed up the food chain from the zebra mussels to the Round Goby, and subsequently to fish-eating birds ultimately resulting in the death of both fish and birds.
The Round Goby’s aggressive nature enables them to dominate prime spawning habitat, displacing native fish. The female Round Goby is capable of spawning as often as three times per season, laying up to 5,000 eggs at once, resulting in their prolific spread. Furthermore, unlike native fish species, round gobies emerge from the egg in a stage of development that makes them less prone to predation.
Why Should We Care:
The Round Goby is displacing native fish by ambushing their spawning grounds, and feeding on eggs and young of these native fish. In addition, the Round Goby is a contaminant to wildlife in the Great Lakes food webs, impacting life at higher trophic levels of the food chain, most notably by spreading botulism to fish-eating birds.
How Can You Stop the Spread:
- Learn to identify the Round Goby
- Empty bait buckets, livewells and bilges prior to leaving any water body
- Do not use Round Gobies as bait (it is illegal to use or have Round Goby in your possession)
- Dispose of unused bait and fish waste in the garbage
- Wash all boating and angling equipment prior to leaving any water body
- Talk to and inform others about the impacts of the Round Goby and other aquatic invasive species
- Support Trout Unlimited Canada’s Stop the Spread program.