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Entries in exotic species (218)

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.

Thursday
Feb092017

Asian Carp Spawning Closer to Great Lakes

Asian carp have moved no closer to the Great Lakes during the past few years. They remain about 50 miles away. But they are spawning closer, and that's bad news.

"The bottom line is that the juvenile front is advancing, and made a big jump last year," said Joel Brammeier of the non-profit Alliance for the Great Lakes. "And we still don't have a permanent solution in place that's going to solve the problem."

That "big jump" was 90 miles.

Two electrical barriers and three locks and dams on the canal/river system serve as the final protection for Lake Michigan. Thus far, they have effectively blocked adult silver and bighead carp. But the smaller ones are much more likely to slip through in the wake of commercial barge traffic, which also can disrupt the effectiveness of the barriers.

"It seems like the wolves are at the door, and the door is still opening and closing," said Daniel O'Keefe of Michigan Sea Grant.

Meanwhile, a third electrical barrier is being constructed upstream of the other two, which are about 35 miles south of Lake Michigan. Intent is to make it more effective against juvenile fish, according to Charles Wooley, deputy director of the U.S. Fish and Wildlife Service's Great Lakes Region.

"There are no fish that are probing these electrical barriers on a daily basis," he added. "The closest these fish are is about 15 to 20 miles downstream, and that leading edge hasn't really changed much in the past five or six years."

 

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
Jan132017

Zebra Mussels Threaten Popular Connecticut Bass Fishery

The largest reservoir in Connecticut and one of its most popular bass fisheries is at risk of infestation by zebra mussels.

"They're not on in Candlewood yet, but they're right on our doorstep," said Len Greene of FirstLight Power Resources, which owns and manages the lake and a hydro power station on it. "It was only a matter of time before they migrated there."

"There" is the station's foundation on the Housatonic River and nearby boulders. In 2009, the invasive mussels were found in nearby Lakes Lillinonah and Zoar and in the river itself.

And the threat lies in way that power is generated, by pumping water between the lake and the river. In the past, FirstLight has voluntarily limited pumping during times when mussels reproduce to lessen the threat, and plans to continue doing so.

"We've been able to buy five years with the pumping restrictions," Greene added. "It's an unfortunate situation that I think was inevitable at some point, given that zebra mussels spread everywhere they can."

As officials try to decide on the best way to repel a zebra mussel invasion, Candlewood Lake Authority has suggested  a smaller than normal winter drawdown to reduce the risk when the lake refills with river water. Typically, water is drawn down 6 1/2 feet to knock back another invasive, Eurasian watermilfoil. Executive Director  Larry Marsicano added that the authority can monitor the area around the intake pipe.

"We're still trying to manage the risk of them getting a toehold," he said. "Even if one gets pumped in, it takes two to tango."

Aside from the threat that they post for blocking water intakes with their dense colonies, zebra mussels also improve water clarity as they feed on algae and plankton. That would allow for more light penetration, encouraging already problematic watermilfoil to grow faster and spread into deeper water.

Wednesday
Jan042017

Record 'Atomic Sunfish' Caught in Florida

Freshwater fishing in South Florida is unique. Largemouth bass share canals and small lakes not only with peacock bass, but with many of their smaller cousins from Central and South America.

Using a lipless crankbait in a Collier County canal, Jonathan Johnson recently established the first state record for one of the latter, a 2.37 pound Mayan cichlid.

“I looked up the record about six months ago and saw that it was vacant,” said Johnson. “I have caught hundreds of Mayan cichlids but only a couple that I thought were large enough. I was targeting them specifically that day and caught about 25, this being the largest one by about half a pound."

The Florida Fish and Wildlife Conservation Commission (FWC) made the Mayan cichlid, a nonnative species from Central America, eligible for state record status in 2012. But the record has remained vacant until now.

It was first reported in Florida in the early 1980s. During the mid-1990s, the fish began expanding its range and has become common throughout south Florida’s freshwater lakes and canals. Both local and out-of-state anglers target the now-popular fish. Its bright red coloration and scrappy disposition when caught prompted FWC biologists to nickname it the “atomic sunfish.”

In fact, the Mayan is equivalent of a bluegill or crappie in more ways than one. Neither largemouths or peacocks are true bass, but the largest members of fish families with lots of relatives, cichlids for the former and sunfish for the latter. Another of the peacock's cousin, the Oscar, is the No. 1 fish caught in portions of the Everglades and the No. 2 fish sought, behind largemouth. Although reputed to grow to a weight of 3 pounds or more, the state record is 2.34 pounds, caught in 1994 in Lake Okeechobee.

The state record butterfly peacock bass, meanwhile, weighed 9.08 pounds, and was taken in Kendall Lakes during 1993.

Following thorough study to determine that this subspecies of peacock would have little impact on the largemouth population, it was intentionally introduced into the canal system around Miami in 1984. Biologists hoped that it would join the bass in gobbling up smaller cichlids that had been released by irresponsible aquarium owners and could threaten native species via their sheer numbers. While doing just that, it also provides an increasingly popular sport fishery.

Many of the 34 species of nonnative fish now established in Florida are cichlids, including the jaguar guapote. As with the Mayan, FWC requires a minimum of 2 pounds to qualify for a state record.

Fortunately, none of these invaders seemed to have caused major disruptions in native ecosystems "or reduced harvest of native sport fishes," said the FWC. But it encourages anglers to keep all cichlids that they catch, except for the legally-introduced peacock.   

"Most exotic fishes provide excellent table fare," the agency said. "In addition, releasing fish from aquariums or moving them between water systems is illegal and could produce detrimental effects."