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Entries in round goby (5)

Thursday
Feb162017

That's Not a Goby . . . THIS Is a Goby!

Fish in the top photo is a round goby, an exotic fish introduced to the Great Lakes in the ballast water of ocean-going ships. They grow to about 6 inches maximum, but 3 to 4 inches is the norm. Also, they have proven to be among the favorite forage for smallmouth bass, and anecdotal evidence suggests that they are growing faster and larger on a goby diet.

Fish in the bottom photo is the world record marbled goby, caught in Thailand by John Merritt. It checked in at 5 pound, 3 ounces. IGFA says that it is "likely the largest of gobies." And with a mouth like that, it likely could turn the tables on some of those smallmouth bass that are eating its smaller, globe-trotting cousin.

You can see more "weird world records" at Sport Fishing.

The International Sport Fishing Association (IGFA) is the official record keeper for both fresh and saltwater species. You can see the full list here. For line class records and additional information, you must become a member.

Wednesday
Jan182017

New Invader in Great Lakes: Thermocyclops Crassus

It's not much to look at. In fact, it's impossible to see without a microscope.

But for the first time in a decade, an exotic aquatic species has been found in the Great Lakes. That makes 185 or 186  non-native species, depending on who's counting, now established in the basin. Some, including the lamprey and alewife, migrated up the St. Lawrence Seaway, but most, including the zebra mussel as well as this latest, probably were introduced via ballast water from ocean-going ships.

Thermocyclops crassus, a type of zooplankton, was discovered in water samples taken from Lake Erie by limnology technician Joe Connolly of Cornell University.

“It’s kind of like looking for a needle in a haystack,” Connolly said. “I didn’t know what it was, but I knew it wasn’t something we’d seen before.”

He found both male and female specimens in low numbers, but enough to say that an established population exists of the invertebrate that is native to Europe, Asia, and Australia. Officials from both the U.S. and Canada have planned more sampling to determine how widespread this new invader is and what its impact may be.

 “We don’t know enough yet about what this species could or could not do in the Great Lakes,” said Elizabeth Hinchey Malloy, an environmental scientist with the U.S. Environmental Protection Agency.

Size isn't an indicator of impact, as the zebra mussel, a fingernail-sized shellfish, and the round goby, a small bottom-dwelling fish, have proven.

Confirmed in 2006, the bloody red shrimp was the last previously discovered invader. It now swarms in excess of 135 individuals per square foot.

"The impact of this species on the Great Lakes is yet unknown, but based on its history of invasion across Europe, significant impacts are possible," said Wisconsin Sea Grant Institute. "The bloody red shrimp is an omnivore. Its diet includes waterfleas and algae. They may compete with young fish, while providing food for larger fish. The invasion of this species in some European reservoirs has been documented to accelerate silica cycling, resulting in blooms of diatoms and, in some cases, plating out of silica onto pipes."

Friday
Mar282014

Mapping the Invasion

This screen shot shows zebra and quagga mussel invasion as of 2006.

Nature Conservancy has produced some great interactive maps showing how invasive aquatic species have spread out across the country from their point of introduction.

Featured species include bighead and silver carp, zebra and quagga mussels, Eurasian ruffe, round goby, sea lamprey, and black carp.

Also, in late 2012, the organization released a report saying that aquatic invasive species “cost businesses and consumer in the Great Lakes region hundreds of millions of dollars annually in direct costs and even more from indirect costs related to removal, maintenance, and management of those species.

“Meanwhile, state and federal governments are currently forced to spend additional millions as they attempt to control the impacts and prevent the spread of AIS (aquatic invasive species).”

According to the report, the largest industry affected by AIS in the Great Lakes is tourism and recreation, which is responsible for employing more than 90,000 people in the region, generating $30.3 billion annually in revenue. Costs range from monitoring and controlling AIS to lost revenue from beach closings affecting hotels, restaurants and other tourism-related businesses.

Tuesday
Nov122013

Round Goby Expansion Continues

 

U.S. Fish and Wildlife Service photo of round goby.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.”

Friday
Apr062012

Scientists Aim Cannons at Round Gobies in Great Lakes

Quickly now, name the most common fish in Lake Michigan, and, yes, the photo above is a clue.

It’s the round goby, an exotic invasive fish that entered the Great Lakes in the ballast water of ocean-going ships, as did so many other aquatic troublemakers, including zebra and quagga mussels.

Huge numbers, of course, bring big problems.

“It has changed the ecology in fundamental ways,” said Jim Grazio, a Pennsylvania Great Lakes biologist in describing its impact on Lake Erie.

The goby’s voracious appetite for the eggs of native fish species is a primary reason for that. That’s why scientists are going to try using an underwater cannon in Lake Michigan this summer.

They hope to frighten away the invaders, at least temporarily during critical spawning times.

Read the full story here.