Get Updates! and Search
No RSS feeds have been linked to this section.











Entries in invasive species (215)


Hydrilla Creeps Closer to Great Lakes

Hydrilla is creeping ever closer to Lake Erie, the warmest and shallowest of the Great Lakes. Most recently, it has been found about 20 miles away in Lake Pymatuning, a 17,000 -acre impoundment on the Ohio/Pennsylvania border.

"It is a serious situation," said Brian Pilarcik of the Crawford County Conservation District. "It can grow very fast, almost an inch a day and forms large, dense masses that can and will impact water sports and will have a negative impact on tourism in the county.

"We are very concerned that the plant could eventually reach Lake Erie."

An environmental educator at Pymatuning, Linda Armstrong added, "The lakes here get quite a bit of use and people will go from one to another, so it is critical to clean all equipment as well as boats."

Already Pennsylvania resource managers have talked with their counterparts in Florida about the discovery, with the latter promising assistance in containing the invasive plant.

Long a problem for many fisheries in the South, hydrilla was first reported in Pennsylvania during the mid 1990s, according to Pennsylvania Sea Grant (PSG).  It's also now established in Bucks County and the Schuylkill River in Philadelphia. The next closest infestation to Pymatuning is Lake Arthur, about 60 miles to the south.

"Hydrilla is a federal noxious weed that continues to spread to new regions in the United States," PSG said. "It is unknown exactly where hydrilla originated, but Asia, Africa, and Australia are all mentioned in the literature as native ranges.

"Currently, Antarctica is the only continent without records of hydrilla."


Asian Carp Spawn Raises Threat for Barkley, Kentucky Lake Sport Fisheries

Can an Asian carp invasion destroy a world-class sport fishery? We're about to find out. And, no, it won't be in the Great Lakes.

Ground Zero will be Kentucky and Barkley Lakes, where anglers and commercial fishermen now are seeing millions and millions of young-of-the year silver carp.

Commercial fisherman Ben Duncan sent me these photos that he recently took at Boswell Bay, where he caught about 500 of them.

"I've seen similar schools in Cypress Bay, Eagle Creek, and Blood River," he said. "My conjecture is this year's mid-summer flood has made the 2015 spawn one for the record books."

And Paul Rister, a Kentucky fisheries biologist, confirmed that assessment. "Yes, we are aware of the tremendous spawn of Asian carp in the tailwaters and lakes this past spring," he said, adding that the state recently implemented a nickel a pound subsidy to encourage commercial harvest.

He also said that the numbers of carp likely will be far more than commercial fishermen can harvest, especially since nets can capture only larger specimens.

"So, what is the answer?" he continued. "There is not one yet. The good news is that it is still very unlikely that the carp have impacted sport fish in the lakes."

They may have displaced them, though, meaning anglers might find the fishing tougher as they are forced to fish new areas. Also, with so much forage, bass and crappie might be more difficult to catch on artificial baits--- at least immediately after the carp spawn. But within a few months, the fast-growing carp are too large for sport fish to eat.

Those impacts are short term. What's going to happen during the next year? Or five? Will the invasion overwhelm the sport fishery as carp occupy so much water that there's no room for other species?  That's happened in portions of major rivers, including the Missouri and Illinois.

Will commercial fishing contain carp numbers? Will scientists develop a chemical or biological control?

We will just have to wait and see.


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."


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.”


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.