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Entries in Great Lakes (117)

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."

Thursday
Jun042015

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.)

Monday
May042015

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.”

Wednesday
Apr292015

Survey Reveals Carp DNA Throughout Chicago Waterway System

If Asian carp aren’t in the Great Lakes, they can’t get much closer. Sampling of the Chicago Area Waterway System (CAWS) last fall revealed carp eDNA throughout the system, including near a lock in downtown Chicago, just one block from Lake Michigan.

“Prevention needs to happen now and the U.S. Army Corps of Engineers and other key decision-makers should take swift action,” said the non-profit Alliance for the Great Lakes (AGL), which charges that the Corps lacks direction, as revealed in its Great Lakes-Mississippi River Interbasin Study.

“DNA evidence is an early detection tool to understand the potential movement of carp, and testing results have consistently found DNA hits on a path closer and closer to the Great Lakes over the past several years of testing,” the group added.

The Corps report outlined eight possible ways to stop migration of Asian carp into the Great Lakes, with the most expensive being an $18.3 billion separation of the CAWS from Lake Michigan. Meanwhile, the Alliance supports measures to temporarily reduce risk, including construction of a new channel and control technologies in the approach to Brandon Road lock and research on reconfiguration of locks in general.

But long-term issues with Chicago’s water system infrastructure must be addressed to keep the carp out, emphasized Jennifer Caddick, AGL spokesperson.

“It’s complicated. You can’t just build one dam and solve the whole problem,” she said. “There’s a lot of work to be done, but we need intensive focus.”

If/when Asian carp become established in the Great Lakes, consequences could be catastrophic for the multi-billion-dollar sport fishery. That’s because the exotic fish are fast-growing, prolific, plankton eaters. They likely would outcompete the many young and adult native fishes that rely on phytoplankton and zooplankton for their primary forage.

Additionally, the U.S. Geological Survey has identified 22 rivers in the U.S. portion of the Great Lakes that would provide suitable spawning habitat for Asian carp.

Sunday
Dec282014

Despite Phase-Out, Pollutant Persists in Fish

Despite being phased out a dozen years ago, a persistent chemical formerly used in Scotchgard still contaminates bass and other fish in the Great Lakes, and urban rivers, according to a recent study by the U.S. Environmental Protection Agency (EPA).

Researchers found perfluorooctane sulfonic acid (PFOS) in all of the 157 fish sampled from nearshore waters in the Great Lakes and in 73 percent from 162 rivers.

“This just shows that PFOS still dominates,” said Craig Butt, a Duke University chemist. “Even though production stopped more than a decade ago, it’s still the main perfluorinated acid in the environment.”

PFOS is a suspected endocrine disruptor that has been linked to low birth weights, reduced immune system function in children, and high blood pressure during pregnancy. EPA hasn’t established a “safe” dose for humans, but Minnesota health officials recommend eating only one meal of fish per week if PFOS concentrations are 40 to 200 parts per billion, and only one meal per month if 200 to 800 parts per billion.

About 11 percent of the fish samples from U.S. rivers and 9 percent from the Great Lakes exceeded 40 parts per billion.

The 3M Company, a major manufacturer of PFOS, voluntarily stopped production in 2002, after scientists discovered the chemical was building up in water, wildlife, and people. PFOS and other perfluorinated compounds were used in oil- and water-resistant coatings for clothes, carpet, paper, cookware, and flame-retardant foams.

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