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Entries in grass carp (27)

Tuesday
Nov292016

Grass Carp: Why You Hate 'Em and Why They Are Needed

Harvest by anglers and bowfishermen has been added as a control measure for grass carp.Anglers have been complaining about grass carp for nearly 40 years. Coincidentally, that's how long fisheries managers have been using the

exotic species as a control for another exotic, hydrilla, along with other invasive aquatic plants.

What's happened recently at Texas' Lake Austin provides a prime example of why they complain. Grass carp released there in 2012 and 2013 have consumed not just the hydrilla, but all of the aquatic plant habitat, which was beneficial for bass and other species. The stocking permit has now been revoked by Texas Parks and Wildlife Department (TPWD), with anglers and bowfishermen encouraged to catch and kill the carp.

"Anglers get angry at us when we stock grass carp, and we understand that," said Dave Terre, TPWD's Management/Research chief, who emphasized that his agency strives to involve fishermen in plans to control invasive plants.

"Everywhere we've used carp has resulted in a complete vegetation community crash," he added. "But it took 10 years for that to happen at Austin. And maybe someday we'll be able to extend that to 20 years. Just three or four years ago, we were promoting the success of grass carp in Austin."

Ten years is a considerable improvement over what happened in the early 1980s. Over the objections of anglers and TPWD, the Texas Legislature authorized the stocking of 270,000 carp into 21,000-acre Lake Conroe. In just two years, aquatic plants were gone, and the long-lived carp kept it that way until the late 1990s.

About the same time, much the same thing happened up in Kansas' Big Hill Reservoir. A heavy stocking of carp "set the reservoir back eight or nine years," said Doug Nygren, fisheries chief for Kansas Department of Parks, Wildlife, and Tourism.

"We regretted it," he added. "It was a wakeup call to be careful."

Yet, there is a flip side to this grass carp decimation story, starting with the fact that Conroe will be the site of the 2017 Bassmaster Classic March 24-26. The impoundment on the San Jacinto River now has not only grass and grass carp, but a first-class bass fishery.

"It's been producing 30-pound stringers all summer long," said Tim Cook, Conservation Director for the Texas B.A.S.S. Nation. "The lake has a significant number of 8-pound fish and I'm expecting that six to ten over 8 pounds will be caught each day. We've had five Toyota Texas Bass Classics on that lake, so anglers know how good it can be."

In short, fisheries do recover, as these controversial exotics remain the best biological method for controlling hydrilla in public fisheries, as well as filamentous algae in private and hatchery ponds. Sadly, though, their use is not a precise science. Inevitably results are cyclical, as they have been at both Austin and Conroe and other impoundments across the country, and often influenced by variables that resource managers have no control of.

Weather is the most prominent. Lower water levels prompted by drought and warmer water courtesy of hotter temperatures combined to power an unprecedented hydrilla growth spurt at Austin, and suddenly 600 acres spread across the 1,600 acre fishery. "It changed the dynamics and threw everything out of balance," Terre said.

Mechanical harvest wasn't an option, because fragmentation spreads the fast-growing exotic. Neither was herbicide, since Austin serves as a public water supply. Additionally, unchecked hydrilla inevitably would impede hydropower generation.

To knock back the plant, the city of Austin's resource managers stocked 33,000 carp from late 2011 through spring of 2013. Contrast that with only 20,000 that had been stocked incrementally for eight years, starting in 2003.

"We could live with 100 acres," said biologist Marcos De Jesus. "But 600 acres was just too much. It was going to cause problems with the turbines."

Terre added, "Anglers sometimes think that we're attacking the habitat of bass. We're not. We know that vegetation is important. But there are multiple users to consider. And grass carp are a tool."

He added that in lakes like Amistad, Falcon, Rayburn and Toledo Bend, with little development, "hydrilla is not a problem for anyone and we don't touch it."

Efforts already are underway to jumpstart aquatic vegetation again at Austin, by growing it in cages, De Jesus said. "There are going to be lots of efforts to restore habitat and to provide more options, with things like brushpiles."

Because it is smaller than Conroe and because state agencies have begun  to partner with other entities, including bass clubs, in recent years to re-establish aquatic vegetation, Terre is hopeful that Austin's recovery will be rapid.

Activist Angler with 30-pound-plus grass carp that was illegally stocked in community lake.Conroe, meanwhile, serves as a model for restoration not only for Austin, but for the nation, with much of the credit going to Seven Coves Bass Club. The B.A.S.S. affiliate spearheaded growing and planting of native vegetation, even as officials continued to combat hydrilla with more stockings of grass carp.

As part of an overall management plan for the lake, the club was awarded a grant for about $45,000 from B.A.S.S. and the U.S. Fish and Wildlife Service to build a plant nursery on property provided by the San Jacinto River Authority. The latter and TPWD also helped finance the effort.

Additionally, occasional harvest by anglers and bowfishermen has been added to the overall strategy for using and controlling grass carp. In 2011, they removed more than 5,000 pounds of carp from Conroe during a tournament.

The event was intended to reduce carp population "to a number capable of preventing re-sprouting of hydrilla but which will allow us and our partners to better enhance important native aquatic vegetation for fish habitat and water quality improvement," said Craig bonds, TPWD's Director of Inland Fisheries.

While habitat initiatives and angler harvest have been added to help control carp and restore beneficial vegetation more quickly, not much has changed in terms of overall strategies for stocking grass carp to keep problematic vegetation under control, said John Biagi, Chief of Fisheries Management for the Georgia Department of Natural Resources.

Two of the most notable are smaller, incremental stockings as opposed to one massive release, and replacing diploid grass carp, which can reproduce in the wild, with triploid, which are sterile and have shorter live spans.  

"And we are learning," said Texas biologist De Jesus. "We're refining the way we monitor the effects of carp on vegetation."

Terre added, "Instead of stocking carp per surface acre, we're looking into doing it per the biomass of the plants. Our goal always is to maintain good aquatic habitat for fisheries."

Other Considerations

Most anglers think about grass carp only in terms the damage that they do to bass fisheries. But they've been used since the late 1960s by aquaculture facilities to keep filamentous algae blooms under control. They still serve that important purpose today, both in hatchery and private ponds.

A disturbing corollary to that, however, is that they also can cause algal blooms, explained Doug Nygren, Kansas fisheries chief. "When they eat the plants, that releases nutrients that can feed those harmful blooms," he said.

At Clarks Hill, meanwhile, grass carp could help save bald eagles, as well as coots, among their favorite prey on that Georgia-South Carolina border reservoir. Researchers say that a toxic cyanobacteria grows on submerged aquatic plants, especially hydrilla. Coots feed on the plants, contract Avian Vacuolar Myelinopathy, and die, as do the eagles that eat them.

"Native plants are coming on and hydrilla seems to be diminishing," said Georgia fisheries chief John Biagi. "We're in discussions with the Corps (of Engineers) on stocking rates. This is a tough one. We don't want to eliminate good habitat, but the eagles have to be considered."

In the Wild

Diploid grass carp are reproducing in Missouri's Truman Lake, and that's just one of many waters where this plant-eating exotic now has sustainable populations, according to Duane Chapman, Asian carp expert for the U.S. Geological Survey.

While Texas reports they are spawning in the Trinity River and Kansas indicates the same for the Missouri, Chapman said, "The Illinois River has a large wild grass carp population."

In fact, he added, they are reproducing in free-flowing waters from Louisiana up into Illinois and Iowa, including in the Mississippi River. And some have turned up on "the wrong side of the (electric) barrier" designed to keep Asian carp out of Lake Michigan. They're also in the Sandusky, a tributary of Lake Erie.

Although some might believe that dams will stop them, Chapman said, "I suspect that when we start looking, we're going to find diploids fairly common above dams."

He added that some believe that silver and bighead carp pose more of a threat to our waterways than grass carp, both because they are more prolific and because data already has revealed how they are outcompeting and replacing native species.

"But grass carp don't require huge populations to have detrimental effects," he said, adding that they could destroy Great Lakes wetlands, re-established through time-consuming and costly mitigation projects.

"Grass carp remove vegetation and they dig, causing destabilization and turbidity," the carp expert continued.

Additionally, diploid grass carp can live nearly 30 years, surviving on very little when plants are scarce. "They just shut down when the food is not there and don't expend energy," Chapman said. "They're just waiting for things to change, and then they gorge."

How did this happen?

"When grass carp were brought into this country by aquaculture facilities in the late 1960s, they weren't worried about security," he said. "The belief was that they wouldn't reproduce."

Sadly, that has proven to be wrong in waters all over the country.

Additionally, while some states now prohibit diploid grass carp, others do not. And anyone can buy them.

"It might be difficult to take them into some states, but it's tough to police that," Chapman said. "States might agree to make diploids less available. But in states like Iowa and Missouri, where grass carp already are all around you, it's not a big issue. There's no downside."

(A variation of this article appeared originally in B.A.S.S. Times.)

Sunday
Aug212016

Grass Carp Invasion Also Threatens Great Lakes Fisheries

Most don't know one carp from another. All are exotic.The photo above is a 30-pound-plus grass carp illegally stocked in a small lake.

Common carp have been in this country for so long (more than a century) that many think they are native. They are not. They were imported by the federal government. Rooting around on the bottom, they have destroyed and degraded many fisheries.

Fish farms in the South and Mid-South imported Asian carp (bighead and silver), and they escaped into rivers, spreading throughout much of the country. Through filter feeding, they gobble up forage needed by many native species, including juvenile sport species.

Grass carp were imported to eat problematic aquatic plants, including hydrilla and Eurasian watermilfoil, also exotic species. Often they were overstocked. Sometimes. they were stocked where they were not needed. Often they were stocked illegally. And they too have escaped and spread.

To add to the confusion, Canadian media and fisheries officials frequently refer to grass carp as Asian carp.

*    *    *    *

Although silver and bighead are the Asian carp of most concern these days for the Great Lakes and its tributaries,  disturbing discoveries have been made lately regarding a third--- the grass carp.

First, a graduate student at the University of Toledo found eggs in the Sandusky River, which flows into Lake Erie. That confirms the existence of a reproducing population of this fast-growing species, which doesn't compete with native fish, but does obliterate beneficial aquatic vegetation.

Additionally, Canadian commercial fishermen recently netted a grass carp weighing more than 60 pounds from the St. Lawrence River, far above Lake Ontario.

Anthony Ricciardi, a biology professor at McGill University, doesn't think that the river has a reproducing population, but suspects that others are in the St. Lawrence as well.

"We actually thought the Asian carp was confined," added Quebec biologist Michel Legault. "But we know that in recent years the grass carp has been found in a small section of Lake Erie. And last summer, nine grass carp were caught in the Toronto area. This is not good news."

On the Sandusky, meanwhile Toledo researchers intend to learn more about the grass carp spawning there, in hopes of finding a way to minimize it.

"Given the similarities in reproductive strategies, this ongoing research on grass carp spawning may help us minimize the risk of bighead carp and silver carp from establishing a foothold in the Great Lakes, said Patrick Kocovsky, a fisheries biologist with the U.S. Geological Survey. "What we learn here also might apply to potential control strategies in tributaries to the Mississippi River.

Today, most grass carp used to control invasive aquatic plants are triploid, meaning they can't reproduce. But fertile grass carp are believed to have first escaped from  an aquaculture facility in Arkansas back in the 1960s. They since have migrated throughout the Mississippi River drainage, as well as spread through authorized, illegal, and accidental introductions to 45 of the 50 states.

Thursday
Jun232016

Solutions Sought to Reduce Hydrilla, Related Eagle Deaths

Sterile grass carp and herbicide applications are the preferred ways to reduce hydrilla, and, by extension, the death of bald eagles at Lake Strom Thurmond (Thomas Hill) on the Georgia/South Carolina border, according to a draft management plan from the U.S. Army Corps of Engineers.

Since 1998, at least 81 eagle deaths there have been attributed to avian vacuolar myelinopathy (AVM). Scientists believe that the birds of prey contract the fatal disease from eating coots, which feed on hydrilla tainted with a toxic blue-green alga.

For five years, the Corps and other agencies have considered control measures for Thurmond, which seems to be Ground Zero for AVM-related eagle deaths. Other options included mechanical harvest and periodic drawdowns.

Of course, anglers are concerned that carp will eat  not only invasive hydrilla, but beneficial native vegetation as well. "What about the loss of fish habitat and the potential damage to the bass fishery and economic impact it has on the region?" said Gene Gilliland, National Conservation Director for B.A.S.S.

Public comment for the plan opened in late April, with public meetings scheduled for May in both Georgia and South Carolina.

AVM was first documented in 1994 at Arkansas' DeGray Lake. Since then, it has been the prime suspect in the death of hundreds of eagles, as well as thousands of geese, ducks, coots, and other birds. It's been confirmed at hydrilla-infested fisheries from Texas to the Carolinas.

“In places where dead eagles are found, invasive aquatic vegetation --- primarily hydrilla --- and the blue-green alga are always present,” said Susan Wilde at the University of Georgia, adding that the number of deaths likely is much higher than can be confirmed because scavenging animals eat the carcasses before they can be checked for the disease that seems to affect only birds.

Monday
May302016

You Think Asian Carp Are a Problem? Look at What the Feds Almost Put in Our Waters

If you think that we’ve made a mess of our lands and waters through intentional and unintentional import of exotic plants and animals, you are correct. For example, we now spend billions of dollars annually to control and mitigate the damage done by just four recently introduced species: bighead carp, silver carp, quagga mussel, and zebra mussel.

And in attempts to minimize problems, the government often has made them worse. During the 1940s, the state of Louisiana touted the South American nutria as a way to control water hyacinth, a fast-growing exotic that was crowding out native vegetation in wetlands. Today, the nutria is eating away those same wetlands, contributing to saltwater intrusion and coastal erosion.

In the early 1960s, the states of Alabama and Arkansas allowed import of grass carp to control aquatic vegetation in aquaculture ponds. By 1970, escapees had established populations in the Missouri and Mississippi Rivers. Today, these troublesome grazers are established in at least nine states and have been sighted in more than 40. Ask just about any bass angler, and he will tell you that the grass carp is public enemy No. 1.

And speaking of carp, we have the federal government to thank for one of the worst management decisions ever in regard to our fisheries. In 1877, the U.S. Commission of Fish and Fisheries began intensively cultivating and stocking common carp. In fairness, it was prompted to do so both by public pressure and by overharvest of native fish stocks. By the turn of the century, however, it already was regarded as a nuisance.

“Moreover, their rapid spread appeared to threaten both water quality and native species, as commissioners nationwide noted a deterioration of formerly clear and fertile lakes and waterways upon the arrival of carp,” says the National Park Service.

But you don’t know the half of it. Actually, things could be worse. Much worse. Instead of nutria eating away those Louisiana wetlands, we could have hippos. And who’s to say that these massive “water horses” which can weigh up to 4 tons and eat up to 100 pounds of vegetation a day, wouldn’t have spread east, west, and north?

They are “relatively tolerant of cold conditions,” says the Glen Oak Zoo, which also points out that “many individuals live to 40 years.”

Oh yeah, they also are generally believed to have killed more people in their native Africa than another animal, including lions and crocodiles.

All things considered, I’ll take the nutria, thank you. It tops out at about 12 pounds and is not as likely to charge me at the launch ramp.

But in 1910, Frederick Russell Burnham, a famed American scout and world adventurer, proposed replacing our nation’s depleted wildlife population --- we had hunted deer, turkey, and buffalo nearly to extinction --- with animals that he had encountered in southern Africa.

His proposal lined up nicely with the search for a solution to the growing problem of water hyacinths in Louisiana waters, as well as America’s need for more meat. Writing about this little known piece of American history, Jon Mooallem in American Hippopotamus, says that Rep. of Robert Foligny of New Iberia “liked to plug up problems with big solutions.”

Thus, Foligny introduced H.R. 23261, also known as the “Hippo Bill,” to “appropriate $250,000 for the importation of useful new animals into the United States.” The Washington Post assured readers that they would see shipments of hippos within a few years.

Fortunately for all us, a boatload of hippos never docked in New Orleans. But it wasn’t because of the unexpected discovery of good judgment in Congress. Rather, one representative said that the beasts should not be introduced because unscrupulous hunters would sneak onto the farms and hunt them for trophies.

Yeah, that’s the reason not to import aggressive animals that boast 20-inch teeth and can run at speeds of more than 20 miles per hour.

What turned the tide, though, was that the Department of Agriculture decided to transform swamps and other undeveloped areas into agricultural land to grow more beef cattle.

Thank goodness. Otherwise, we might we watching “Hippo Die-Nasty” instead of “Duck Dynasty” on television.

Thursday
Oct292015

National Policy Needed to Help Stop Spread of Grass Carp

This grass carp was illegally stocked in a lake where it wasn't needed, and the health of the fishery has suffered as a consequence. Photo by Robert Montgomery

Although grass carp have been found in every one of the Great Lakes except Superior, resource managers don’t believe that the exotic fish have established a self-sustaining population.

But the Mississippi Interstate Resource Association (MICRA) recently warned that “state grass carp regulations are varied and inconsistent, and a national policy strategy is needed to effectively minimize the risks of additional fertile and sterile grass carp introductions into the Great Lakes.”

MICRA reached that conclusion as result of a study funded by the U.S. Fish and Wildlife Service (FWS) to look at grass carp use, production, and regulations. It also made recommendations to help minimize risk not only to the Great Lakes, but other waters not yet infested by unintentional introductions of this aquatic invader.

Those recommendations include the following:

  • Production, shipment, stocking, import, and export of diploid (fertile) grass carp should be prohibited except by licensed facilities.
  • States that allow production of triploid (sterile) grass should develop a set of minimum standards, permit requirements, and recordkeeping for diploid broodstock.
  • States that allow importation of triploid carp should adopt consistent regulations that allow only FWS-certified fish.  Also, increase random inspections and enforcement of regulations in these states.
  • FWS should work with states, producers, and other partners to develop testing procedures for quality controls and law enforcement in support of random inspections.

Grass carp, a species of Asian carp, were first imported into the U.S. in 1963 as a tool to manage nuisance aquatic vegetation, including exotic hydrilla, in ponds and impoundments. But flooding allowed many to escape into rivers and streams and, by 1970, they were reported in the Mississippi River basin.