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Entries in exotic species (194)

Monday
Aug242015

Sport Fisheries in Kentucky and Barkley Lakes Under Assault From Asian Carp

Photo by Mark Marraccini, Kentucky Fish and WildlWhile we have been looking one way, Asian carp have been swimming in another.

For years, most media, scientific, and political attention was focused on the threat that silver and bighead carp pose to sport fisheries if they become established in the Great Lakes. Meanwhile, some of these invaders took at right turn at the Ohio River, and their numbers now are exploding in Kentucky and Barkley Lakes, even as they continue their infestation of other fisheries along the Cumberland and Tennessee River. What's occurring here is not hypothetical; it's real.

In the October issue of B.A.S.S. Times, I'll have a detailed report on what's happening to these fisheries and what might be done to save them. Following are some comments about the situation from anglers, as well as the fisheries chiefs in Kentucky and Tennessee

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"When I was on Kentucky Lake in June, they (Asian carp) were everywhere, hitting the surface on the ledges. You could look down and see schools of them. Kentucky Lake is doomed in the very near future."

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"Yep, they are thick in Kentucky Lake, but people don't see them jumping  like in other areas. But I see them all the time on my sonar and Steve had one jump into his boat and hit him in the back a few years ago."

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"Yesterday i went to Smithland. The 4-inch Asian carp are 15 feet thick in places next to the dam in the still water and are so plentiful around the bank area that they are actually jumping up on each other and lying there out of the water."
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"Fishing as we know it is winding down! Not one striper at any of the dams right now!"

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"The two species of Asian carp that we are most concerned about right now because of their numbers are the bighead and silver carp," said Ron Brooks, Kentucky fisheries chief.

"Silver carp eat phytoplankton. Bighead eat primarily zooplankton, and, together, the two species threaten the very base of the aquatic food pyramid. By eating phytoplankton, silver carp reduce the amount of food available to many zooplankton species, which reduces the amount of zooplankton. Bighead forage on zooplankton, which also reduces the amount of zooplankton . . .

"Without sufficient densities of zooplankton available shortly after hatching, bass, crappie, bluegill, and even walleye would have poor survival into the juvenile phase of their lives. That is why we are most concerned about controlling the invasive carp numbers."

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"We have had several inquiries from a few Chinese businessmen but nothing has developed so far.  We have also had one group from Tennessee that has been exploring the possibility of constructing a processing plant but they are still looking for a source of funding (10 to 12  million dollars)," said Bobby Wilson, Tennessee fisheries chief.

"However, with the three (plants) in Kentucky, there is a market for harvesting Asian carp in Tennessee waters.  There is a need to coordinate the harvest of Asian carp by commercial fishermen with the purchase of Asian carp by the fish processors. We are working to try to make that happen."

Friday
Aug212015

Tennessee, Cumberland River Fisheries Threatened by Asian Carp

Most anglers know that Asian carp are overwhelming populations of native fish in portions of the Mississippi, Missouri, and Illinois Rivers. Likely they are aware that the invaders could have catastrophic consequences for the sport fishery if they migrate into the Great Lakes.

And almost certainly they have seen photos of silver carp leaping from the water, like the one above, as they are frightened by passing boats. This iconic shot was taken in 2007  by Nerissa McClelland of Illinois Department of Natural Resources from the chase boat as an electrofishing survey was conducted on the Illinois River, just upstream from Havana.

What most anglers do NOT know is that silver and bighead carp also threaten the Tennessee and Cumberland River systems , along with the world-class sport fisheries in their reservoirs. Most at risk right now are Kentucky and Barkley Lakes, but the invaders are moving steadily upriver from there.

In the October issue of B.A.S.S. Times, I'll have a detailed report on what's happening to these fisheries and what might be done to save them. Following is some insight regarding the problem from Ben Duncan , a commercial fisherman:

"I think it's too late to fully save the Mississippi and Ohio Rivers. The quantity of carp in both those rivers is unimaginable, although sustained fishing does help. If we don't start soon, the Tennessee and Cumberland Rivers will soon follow.

"Using the Cumberland River as an example, the numbers on the Barkley pool are large, while two pools up--- Old Hickory Lake --- catches, while becoming more frequent, are still at manageable levels.

" I have been on these lakes all my life, and spend more time on the water in a year than most people do in 10, and I can already see how native fish are changing their behaviors due to the invasion of carp. I think it's even influenced the crappie population and spawn on Kentucky Lake. Commercially, we catch way fewer fish in the bays than we did seven or eight years ago---  especially buffalo--- a fish that competes with Asians for food. Such large schools of carp decimate the food source so there's no reason to enter the bays. I have observed the same patterns in gizzard shad. 

"Currently, commercial harvest is the only defense. Kentucky and Barkley lakes are two of the most productive reservoirs in the country and it's concerning that Asian carp have made them so vulnerable. There are still several anglers unaware of the severity of the problem and most need to be educated on how tackling the problem is a collaborative effort among all stakeholders."

Friday
Aug072015

Florida Fishery Restored by Dedicated Volunteers

The way it used to be: Gator sunning in the muck at Lake Trafford. Photo by Naples Daily News

Those who doubt that hydrilla can destroy a fishery need look only to Florida’s Lake Trafford.  Nearly 40 years ago, the invasive plant covered its 1,500 acres, and efforts to control the plant with herbicides resulted in a buildup of muck that reached 6 feet deep in places. 

That organic debris smothered native plants and hard bottom, fed algal blooms, and led directly to several fish kills, culminating with a massive die-off in 1996.Less than 20 years later, however, Lake Trafford also is a testament to what anglers and other involved citizens can do to make a difference. The fishery once again is vibrant and healthy, as evidenced by three TrophyCatch bass (8 pounds or better) being caught there earlier this year.

“A number of dedicated people, past and present, put in a lot of effort and energy to help bring this fishery back,” said Jon Fury, deputy director of the Division of Freshwater Fisheries for the Florida Fish and Wildlife Conservation Commission (FWC). “Seeing a largemouth bass entered into TrophyCatch from this lake is very gratifying.”

That effort began with Annie Olesky, who started a campaign to raise money to remove the muck.  Sadly, the wife of Ski Olesky, owner of Lake Trafford Marina, died just before the multi-million-dollar project began in 2005. Financed by Friends of Lake Trafford, FWC, the South Florida Water Management District, and the Collier County Tourist Development Council, the project began with 6.4 million cubic yards of muck being dredged from the lake.

“The removal of the muck was a key step,” said FWC biologist Barron Moody. “It impacted the ability of fish to spawn. It also reduced nutrient loading and improved water clarity so sunlight can get to submerged vegetation.

Plantings of bulrush, pondweed, and other native plants followed, as did stocking of 500,000 largemouth fingerlings by FWC. But those recent TrophyCatch bass weren’t the result of those 2010 and 2011 stockings. They were a few of the hearty survivors.

“In our sampling, we’ve seen that the hatchery fish aren’t that large,” Moody said. “They’re more in the 2- to 3-pound range.”

Additionally, hydrilla remains in the lake, but FWC and the water district are hopeful that they can keep it under control this time.

“I am so very proud of the partnership built between our local community, Collier County, the FWC, and partner agencies,” said FWC Commissioner Liesa Priddy, “The grassroots efforts by the local community, businesses and the people of Collier County set in motion the process that brought us to this successful conclusion -- this celebrated catch.”

Thursday
Jul302015

Exotic Catfish Are in Our Waters Too

Asian carp are the exotic fish species that we hear the most about, but plenty of others are established in our waters as well, mostly because of an under-regulated exotic pet industry and irresponsible aquarium owners. Clinton Richardson recently caught this unusual catfish while fishing the lower Susquehanna River.  Biologists identified it as a hybrid catfish from the aquarium trade, a cross between a redtail catfish and a tiger shovelnose catfish. Both grow large in their native South America.

"Irresponsible aquarium owners continue to introduce exotic and at times invasive fish to our waterways when their pet fish become too large or they tire of them," noted the Maryland Department of Natural Resources. "The introduction of the northern snakehead is a perfect example."

The big question now is whether climate is too cold for such exotic catfish to establish breeding populations that far north, if they haven't already.

USGS photo

In Florida, meanwhile, the suckermouth armored catfish, also from South America, is firmly entrenched over much of the peninsula. And almost certainly it came from the aquarium trade as well, as it often is labeled a "plecostomus" or "algae eater."

The burrows that they make for spawning likely cause or exacerbate erosion on shorelines of canals and rivers, although no quantitative data is available on that. Additionally, they have been observed browsing on the algae that frequently grows on the backs of manatees.

"Manatee responses varied widely; some did not react visibly to attached catfish whereas others appeared agitated and attempted to dislodge the fish. The costs and/or benefits of this interaction to manatees remain unclear," said the U.S. Geological Survey.

Friday
Jul102015

As Predictable as Summer: Another Toothy Exotic Caught in U.S. Waters

Every year, anglers catch tropical pacu, a vegetarian cousin of the piranha, in waters across the United States.  For example, Holley Luft caught a 14-inch specimen in Michigan’s Lake St. Clair last July. They do so because irresponsible aquarium owners release them into lakes and rivers.

And more infrequently, for the same reason, anglers catch one of those fish with the razor-sharp teeth and a reputation for tearing flesh to shreds. That’s what happened late this spring, when Roger Headley pulled a piranha from Arkansas’ Lake Bentonville.

“I about messed my pants,” Headley said.

Arkansas Game and Fish Commission confirmed the catch and a spokesman said the fish was “probably a pet that got too large or difficult to manage.” He added that a variety of exotic species are found in state waters annually, including an octopus in Lake Conway in 2003.

Another piranha was caught at Hickory Creek Marina on Beaver Lake in 2014. Several have been found at Missouri’s Lake of the Ozarks since 2007.

In trying to allay fears, especially regarding piranhas, fisheries managers always are quick to point out these tropical invaders can’t overwinter and reproduce because they are intolerant of cold.

But that is not always the case, as B.A.S.S. Times revealed two years ago. The Jack Dempsey, a tropical predatory fish related to the peacock bass, is thriving in South Dakota’s Fall River. How is that possible?

“The hot springs in the river makes it perfect for cichlids,” Mike Smith, aquatic nuisance species coordinator for South Dakota Game, Fish and Parks, said in 2012. “We first found a Jack Dempsey there in 2009. Then, two weeks ago, we found multiple-year classes.”

“And there’s no way that the fish could have gotten there except aquarium release.”

In that case, the Jack Dempsey’s impact on native species likely will be minimal. Few other predators live in the shallow water, and forage species gobbled up by the aggressive cichlid can be replenished from populations outside the range of the hot spring’s influence.

But the discovery was significant because it confirms that exotics can use thermal refuges provided by springs or warm-water releases from power plants to survive in cold climates. Will pacu be the next South American exotic to find such a hospitable environment?

Or maybe piranha?