Since first discovered in 1990, the round goby has prospered in the Great Lakes, but that doesn’t mean the bottom-dwelling fish is content to stay there.
More and more in recent years, it has expanded its range. For example, it’s now established in about 170 miles of Wisconsin rivers and streams that feed Lake Michigan. The native of Eastern Europe also has moved into Ontario’s Trent River, Rice Lake, and Simcoe Lake, one of the province’s most famous smallmouth fisheries.
Most recently, it has been found in Cayuga Lake, the longest of New York’s Finger Lakes, and it also is suspected in Oneida. That expansion likely will be a mixed blessing, as it has been in the Great Lakes.
In Cayuga and Oneida, gobies may prey on eggs of lake trout, sculpin, and darters, according to the Cornell Cooperative Extension Invasive Species Program. Additionally, they make crowd out native species, including bass, from prime, nearshore spawning areas.
“The biggest concern for anglers is that when gobies get to high density, the prey fish will have plenty of food to eat, and it might be harder to catch fish,” said Cornell biologist Randy Jackson.
For smallmouth bass anglers, however, that hasn’t been the case in waters where gobies have long been established.
“They’ve been a huge plus in Lake Ontario and the St. Lawrence River, where (zebra) mussels came in first and then gobies came in to eat the mussels,” said guide Dean Meckes, who fishes those waters, as well as Cayuga and Oneida.
“Smallmouths are getting way bigger now,” he added, pointing out that 11 pounds often won a one-day tournament in the 1990s.
“Now you need 20 to 24 pounds (five fish) to win,” he continued. “In a tournament last weekend, I had 21-4 on the first day and was in fourth place. First place had 26 pounds.”
Research on Lake Erie, meanwhile, shows that young smallmouths are growing faster. Ohio biologist Kevin Kayle theorizes that is because gobies spawn late into the summer, allowing young-of-the-year bass to move more quickly to a fish diet.
On the negative side, Kayle said, “We’ve seen a decline in sculpins and darters because of gobies.”
Another concern is that toxins bio-accumulate in gobies as they feed on zebra mussels. The exotic fish then are eaten by birds and larger fish. Researchers believe that loons and other fish-eating birds have died of botulism because of this. The invaders, which grow to 6 or 8 inches, also are considered a nuisance by some anglers because they are such proficient bait stealers.
And This Just in . . .
After I wrote the above article for B.A.S.S. Times, I received this additional information from Randy Jackson, a fisheries scientist at Cornell University Biological Field Station on the shores of Lake Oneida:
“In general, we hate to see any new invasives enter our inland lakes because impacts are never predictable.”
The major threat that the goby poses is to bass reproduction, he said.
“Most people focus on impacts on bass nests where guarding males have been removed. While no doubt individual nests would be at risk if males were removed, we certainly haven't seen any reduction in bass production in Lake Erie with the combination of spring fishing and gobies.
“I suspect it is the classic question of individual nest threats and lakewide production risk. I'm inclined to think that except under circumstances of extreme spring fishing pressure that we would not likely see any system wide reductions in bass production with gobies.
“Many of the other likely goby activities would very likely be positive to sport fish. Where they occur, both walleye and bass seem to make great use of them, so they would likely represent an additional prey resource that could result in faster growth rates.
“They spawn throughout the summer so there will potentially be a steady supply of small fish prey for young bass and walleye. We know in Oneida that young walleye have had some difficulty remaining piscivorous through the summer due to poor yellow perch production, so gobies might be a benefit to them.
“Double-crested cormorants also like gobies, so gobies could represent an additional buffer for sport fish to cormorant predation. And gobies eat zebra and quagga mussels, which we have plenty of.
“I suppose my primary concern is how gobies might impact angler catch rates. While we don't have great data for bass, we have seen that in Oneida, walleye catch rates are very tightly linked to the abundance of forage for adult walleye, not the numbers of adult walleye. In years when yellow perch produce large year classes, small perch are readily available to walleye and angler catch rates go down.
“In years when perch are rare, walleye catch rates are high. Gizzard shad play a similar role. When they are abundant, walleye can be hard to catch.
“If gobies establish at high densities, they could negatively impact angler catches. So adult game fish may grow faster but anglers won't have as much luck catching them. There is some irony in that gobies could potentially benefit many dynamics of our sport fish but at the same time create conditions where it is more difficult for anglers to benefit from that.”