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Entries in grass carp (26)

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.

Friday
Apr102015

Grass Carp Gobble Up Lake Austin's Grass, Reputation

 

Gut contents of a Lake Austin grass carp. Photo by Brent BellingerAs grass carp gobbled up all the aquatic vegetation in Texas’ Lake Austin, they also obliterated the reservoir’s reputation as one of the nation’s top bass fisheries.

“When the grass was around 400 to 500 acres for a couple of years, the bass fishing really took off,” said John Ward, marketing director of the Texas Tournament Zone (TTZ). “The fish were fat and healthy. We had a great sunfish and crawfish population, and plenty of ambush spots for the big girls to grab them.

“Now sunfish and crawfish numbers are significantly down. You see more schools of bass chasing shad balls instead. The worst feeling is when you finally get a big girl, and it’s a 10-pound head with a 5-pound body. They just can’t eat like they used to.”

Understandably frustrated anglers blame mismanagement and/or the powerful influence of lakefront property owners who don’t like hydrilla. For example, one said that Texas Parks and Wildlife (TPW) “grossly overstocked this lake with grass carp.”

He continued, “In less than a year, we have seen complete devastation of this great fishery. The grass is 100 percent gone. Reeds that used to line the lake in places have been uprooted and chewed off at the stalks.”

But the reality is more complex and less malevolent. What happened was the inevitable result of an unavoidable set of circumstances involving weather, two exotic species, and reservoir management priorities.

“This trophy fishery was maintained along with grass carp stockings for many years,” said Texas biologist Marcos De Jesus.

“This extreme drought scenario has thrown a monkey wrench in our management efforts, but we are learning from this experience to avoid a similar outcome in the future.”

Managed by the Lower Colorado River Authority, Austin is a 1,599-acre riverine impoundment on the Colorado River. During normal times, cool discharges into the flow-through fishery combine with a sustained population of grass carp to keep hydrilla in check. Also, less problematic Eurasian watermilfoil thrives, serving as another control. But starting in 2011, drought diminished flow, allowing water to warm and igniting an unprecedented growth spurt in hydrilla. By spring 2013, hydrilla covered nearly a third of the reservoir.

If not kept in check, hydrilla can block flow, pushing water onto highly developed shorelines, De Jesus explained. Consequently, more dramatic control was required, and it could only be done with grass carp. Herbicides are not an option for Austin, which also serves as a municipal water supply.

A stocking of 9,000 carp in May 2013 supplemented 17,000 introduced in 2012, providing 55.5 fish per acre of hydrilla. And, as anglers watched in dismay, the fish quickly gobbled up all of the lake’s aquatic vegetation, except for shoreline plants protected by cages.

“Now we are in a situation where the carp are keeping everything at bay,” said the biologist. “Every time it’s been down to zero, though, it bounces back. We’re now looking at creating habitat (brushpiles) and doing some carp removal.

“Fishing always has been our priority,” he continued, pointing out that electrofishing revealed bass still are plentiful.

“But they’re now suspended in deep water, and people will have to transition to other fishing styles. We were all spoiled. We all loved that lake, and this change was not one that we wanted.”

Brushpiles will help, said Ward, who added that TTZ will help organizes anglers to assist. “But nothing can replace natural habitat. As long as you have 20,000-plus grass carp in a 1,600-acre lake, grass will not grow.

“It’s the aquatic vegetation and the healthy habitat it provides that brings out the potential for big bass in Lake Austin.”

(This article was published originally in B.A.S.S. Times.)