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Entries in Great Lakes (119)


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."


Less Habitat --- Not More --- Might Help Asian Carp Spread

Who would have believed that you could catch a largemouth bass, or much less a spotted bass, on a 9-inch swimbait? And how about that crazy looking Alabama rig? No way would that work.

But it’s not only in bass fishing that nature constantly reminds of how little we know.

Perhaps the coelacanth provides the best example. The primitive fish was thought to be extinct for about 65 million years when one was pulled from the depths in 1938 off the coast of South Africa. Since then, several more have been caught, including some 6,000 miles from the original location.

More recently, scientists say that they believe that a reservoir 400 miles below our feet contains enough water to fill our oceans three times. If true, this suggests that our surface water actually came from within, instead of being deposited by icy comets striking Earth billions of years ago. It also makes one wonder what the planet would look like if all that water were up here instead of down there. Those who are religious might say it would look much like it did shortly after Noah built his arc--- and they might add that explains where the water came from.

Exotic species, meanwhile, provide some of the greatest--- and costliest--- of nature’s mysteries. And, as speedier transport and improved technology facilitate their spread, they will continue to do so. That’s because the consequences of their introductions can’t truly be determined until it’s too late. Yes, we can theorize based on their size, needs, breeding habitats, etc., and the niches that they filled in their native habitats.

But as we’ve learned in recent years, zebra mussels, Asian carp, and other invaders are not subject to the same limiting factors--- predation, disease, climate, habitat--- as they were in their native ecosystems. In other words, what it was there is not what it is here.

Yes, we knew that zebra mussels would filter the water in the Great Lakes. But we had no idea that this process would contribute to a resurgence in blue-green toxic algae blooms or that the shellfish would link with another invader, the round goby, to cause fish-eating birds such as loons to die of botulism poisoning. Yes, we knew that Asian carp would compete with native species for food and habitat. But we had no idea that the silver would become a serious navigation hazard on some waters because of its leaping when frightened.

Which brings us to a recent revelation by a scientist at the University of Waterloo in Canada. Her proposal turns on its head the idea that Asian carp and other exotic species require an abundance of suitable habitat to thrive and spread. And if she’s correct, that means total lockdown of the Great Lakes from its manmade connection with the Illinois River is more important than ever.

“We recently found that only 10 Asian carp are needed to establish a population in the Great Lakes,” said Kim Cuddington, an ecology professor. “But then we asked, if there are so few individuals initially, how do they find a mate and create an ecological disaster?”

The answer is “landmarking.” And it works this way: Where is it easier for you to locate bass, in a pond with one laydown or a pond with a dozen? Yes, fishing might be better overall in the latter, but that’s not what we’re talking about.

We’re talking about a “hook up” --- forgive the pun--- in a non-angling sense. Whether a lonely male is an Asian carp or a butterfly, he instinctively knows to hightail it to the nearest preferred landmark habitat--- or "hangout"--- of his species to find a mate. This strategy allows species to reproduce even when population densities are low.

"With an endangered species, if the number of landmarked sites is increased, the individuals will have a lower chance of finding a mate," said Cuddington. "By contrast, decreasing the number of landmarked sites in an effort to keep invasive species from reproducing has the opposite effect, and ensures individuals have a near certain chance of finding a mate.”

Asian carp use river water quality and flow rate as landmarks to find mates more easily than originally thought, she explained.

"For species like Asian carp, precautionary measures have to be extraordinary to prevent establishment in the Great Lakes," said Cuddington. "When we see Asian carp use landmarking, officials need to worry."

(This article appeared originally in B.A.S.S. Times.)


Lionfish Threat Continues to Spread

As harmful invasive fish species, Asian carp seem to garner most of the headlines, mostly because of the threat that they pose to the Great Lakes.  But the lionfish, a marine invader from the Pacific Ocean, is decimating native species through much of the Caribbean, as well as spreading up the Atlantic coast and across the Gulf of Mexico. (See previous post.)

And now it’s been discovered off the coast of Brazil, which suggests the entire  coast of South America likely will be invaded.

“When the researchers analysed the fish’s DNA, they found that it matched the genetic signature of the Caribbean lionfish population, and not that of specimens from their native Indo-Pacific region. This suggests that the fish may have reached Brazil through natural larval dispersal from the Caribbean, the study’s authors say,” reports Nature.

“But Mark Hixon, a marine ecologist at the University of Hawaii at Manoa, says that ocean currents typically flow in the wrong direction for larval dispersal from the Caribbean to the southeastern Brazilian coast. He says that it is just as likely that the lionfish was brought to Brazil by humans. ‘Lionfish are easy to capture and make beautiful pets,’ says Hixon. ‘It’s easy to imagine boaters carrying lionfish as short-term pets in bait tanks or other containers on their vessels.’”

The Invasive Species Action Network adds this:

“Lionfish are vicious predators that eat any fish or invertebrate they can fit in their mouth. They reproduce easily and the rate at which they have expanded their range shows that they are thriving in this environment. With no predators in our waters they are rapidly impacting many habitats.

“Humans can have an impact. Fortunately, lionfish are very tasty and many restaurants have added them to the menu. In many areas concentrated spearfishing is keeping local populations in check but this is not a practical method of control across their range. In the USA, NOAA is the lead agency on this problem and they are the best source for lionfish information and research.

“NOAA has recently released the draft National Invasive Lionfish Prevention and Management Plan While the plan is still in draft form, it is scheduled to be approved at the next meeting of the Aquatic Nuisance Species Task Force meeting scheduled for the first full week in May.”