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Entries in invasive species (179)

Friday
Dec272013

Electric Barrier Isn't Keeping Fish Out of Lake Michigan

 

You know that expensive electric barrier erected to keep carp out of the Great Lakes?

Uh, well, that isn’t working so well, according to a new report from the Army Corps of Engineers. That’s because small fish can ride in on the flow behind barges crossing the barrier.

In a new report, the Corps says the following:

"Initial findings indicate that vessel-induced residual flows can trap fish and transport them beyond the electrical barriers, and that certain barge configurations may impact barrier electric field strength. Additionally, the preliminary (sonar camera) findings identified the potential for small fish (between 2-4 inches in length) to pass the barrier array in large groups, or schools."

Crews dropped in a camera 10 minutes at a time to see what was happening. In 61 percent of the 72 samples, they saw entire schools of fish, “not believed to be Asian carp,” swimming through.

But not to worry:

"There is no evidence that Asian carp are bypassing the barriers. Nor is there any indication that Asian carp are in the vicinity of the barriers," states the report. "The closest adult Asian carp found in the Illinois River are about 55 miles from Lake Michigan, and no small Asian carp have been observed closer than 131 miles from Lake Michigan."

So . . . it’s okay that we are spending millions of dollars to maintain a barrier that doesn’t work because, well, it doesn’t have to work because the Corps says the invaders are far, far away and don’t pose a threat.

Gee, that makes me feel so much better. I have to wonder, though, if the Corps is as competent at estimating the threat as it is at defending against it. 

Friday
Dec272013

Snakehead is Carrier of LMBV

Scientists have confirmed the presence of Largemouth Bass Virus (LMBV) in northern snakeheads taken from two Potomac River tributaries.

That might seem a positive development for those who view the exotic predator as a threat to bass and other native fish. After all, LMBV killed thousands of bass during the late 1990s and early 2000s; now maybe it will do the same to snakeheads.

But that’s not a foregone conclusion. The virus doesn’t always turn into a deadly disease. As a result, researchers caution that snakeheads simply could be carriers for spreading LMBV to bass throughout the Chesapeake Bay watershed, especially since the two share similar habitats.

“The virus has been found in bass, sunfish, and other fish species, but largemouth bass is the only species known to develop disease from it,” reported the U.S. Geological Survey (USGS).

USGS and Virginia Department of Game and Inland Fisheries made the discovery while studying snakeheads for possible pathogens. Until now, little has been known about what diseases this introduced predator might carry and/or be susceptible to.

In 2011, though, researchers found bass with LMBV in all 16 bodies of water tested in Virginia, except the tidal James River.

“The long-term and population-level effects of Largemouth Bass Virus on bass inhabiting these rivers are unknown,” added Luke Iwanowicz, a USGS research biologist.

Meanwhile, efforts to control the spread of snakeheads have been unsuccessful, the USGS pointed out, with scientists predicting they likely will expand their range.

Tuesday
Nov262013

Carp Threat Moves East

This Asian carp was caught at Kentucky Lake, Photo by Steve McCadams.

Asian silver carp DNA has been found as far up the Ohio River as Wheeling, West Va., and Pittsburgh, Pa. That’s bad news for East Coast river fisheries.

The silver is most noted for leaping from the water when frightened, injuring passing anglers and other boaters. But the most damage is being done to our waterways, as silver and bighead carp crowd out and outcompete native species for food and habitat.

"Unfortunately, the test results provide some evidence that this invasive species could be in the upper Ohio River in Pennsylvania," John Arway, executive director of the Pennsylvania and Boat Commission.

 "This is an early warning sign, since we don't know for certain the origin of the genetic material. We don't know if the eDNA came from live or dead fish or if it was transported from other sources, like bilge water or storm sewers, or even waterfowl visiting the basin."

For years, most of the focus was on the fear that Asian carp would devastate fisheries in the Great Lakes when/if they gain entrance. But now they also are threatening the inland waters of Iowa, South Dakota, and Minnesota, as well as the Cumberland and Tennessee rivers and their reservoirs, including Kentucky and Barkley lakes.

Read more here.

Monday
Nov182013

Safe Launch Saves Boaters Coming and Going

Photo from www.boattest.com

If you haven’t forgotten to put in the drain plug before you launch, chances are that you know someone who has.

Consequences can range from aggravating--- fishing is delayed--- to catastrophic--- the boat sinks.

But did you know that pulling that plug when you exit the water also is important? That’s because of the threat posed to our fisheries by exotic mussels and other invasive aquatic species, which can hitchhike in water left in the boat. Once established in a new water body, they crowd out native species, smother fish habitat, and block intakes, endangering public water supplies.

As zebra and quagga mussels have spread into Minnesota, across Texas, and over the Rocky Mountains, the danger has become even more acute, and resource managers are taking action. For example, the Texas Parks and Wildlife Commission recently approved a rule requiring anyone leaving or approaching public waters in 17 north Texas counties to drain their boats and is proposing that 28 additional north and central counties be added to the mandate.

In some places, forgetting to take out that plug is going to hit anglers and other boat owners in the pocketbook, as they are fined for violating the law. That’s how seriously resource managers are taking this threat.

But for a few bucks you can be pro-active to protect yourself, your boat, and the resource, courtesy of the Safe Launch Drain Plug Reminder System developed by Steve Colsher and Ray Haber.

It’s ingenious, but simple and easy to install. You just place a metal flex hook into the drain hole.  The hook is attached to a lanyard with a split ring carabineer that easily attaches to one of the transom/trailer tie-down straps. When you disconnect the tie-downs, you can’t help but be reminded to remove the hook and insert the plug.

Conversely, when leaving the water, you will see the Safe Launch lanyard, which will remind you to remove the plug and insert the hook, which does not impede water drainage.

Colsher told Activist Angler that he originally came up with the idea as a way to remind himself to put in the plug on his own boat. “But as time went on, and we were looking into things, we began to see this as a safety product that could save people $500 or $600 if they forget to plug out the plug.”

It also can help prevent the spread of invasive species, which is why the Lake Havasu Marine Association is partnering with Safe Launch. It promotes Safe Launch as part of its “clean, drain and dry” program for boats, while the company donates a percentage of sales to the association.

“This is a model that I think will work well with other associations,” Colsher said. “It’s a win-win for both.”

Tuesday
Nov122013

Round Goby Expansion Continues

 

U.S. Fish and Wildlife Service photo of round goby.Since first discovered in 1990, the round goby has prospered in the Great Lakes, but that doesn’t mean the bottom-dwelling fish is content to stay there.

More and more in recent years, it has expanded its range. For example, it’s now established in about 170 miles of Wisconsin rivers and streams that feed Lake Michigan. The native of Eastern Europe also has moved into Ontario’s Trent River, Rice Lake, and Simcoe Lake, one of the province’s most famous smallmouth fisheries.

Most recently, it has been found in Cayuga Lake, the longest of New York’s Finger Lakes, and it also is suspected in Oneida. That expansion likely will be a mixed blessing, as it has been in the Great Lakes.

In Cayuga and Oneida, gobies may prey on eggs of lake trout, sculpin, and darters, according to the Cornell Cooperative Extension Invasive Species Program. Additionally, they make crowd out native species, including bass, from prime, nearshore spawning areas.

“The biggest concern for anglers is that when gobies get to high density, the prey fish will have plenty of food to eat, and it might be harder to catch fish,” said Cornell biologist Randy Jackson.

For smallmouth bass anglers, however, that hasn’t been the case in waters where gobies have long been established.

“They’ve been a huge plus in Lake Ontario and the St. Lawrence River, where (zebra) mussels came in first and then gobies came in to eat the mussels,” said guide Dean Meckes, who fishes those waters, as well as Cayuga and Oneida.

“Smallmouths are getting way bigger now,” he added, pointing out that 11 pounds often won a one-day tournament in the 1990s.

“Now you need 20 to 24 pounds (five fish) to win,” he continued. “In a tournament last weekend, I had 21-4 on the first day and was in fourth place. First place had 26 pounds.”

Research on Lake Erie, meanwhile, shows that young smallmouths are growing faster. Ohio biologist Kevin Kayle theorizes that is because gobies spawn late into the summer, allowing young-of-the-year bass to move more quickly to a fish diet.

On the negative side, Kayle said, “We’ve seen a decline in sculpins and darters because of gobies.”

Another concern is that toxins bio-accumulate in gobies as they feed on zebra mussels. The exotic fish then are eaten by birds and larger fish. Researchers believe that loons and other fish-eating birds have died of botulism because of this. The invaders, which grow to 6 or 8 inches, also are considered a nuisance by some anglers because they are such proficient bait stealers.

And This Just in . . .

After I wrote the above article for B.A.S.S. Times, I received this additional information from Randy Jackson, a fisheries scientist at Cornell University Biological Field Station on the shores of Lake Oneida:

“In general, we hate to see any new invasives enter our inland lakes because impacts are never predictable.”

The major threat that the goby poses is to bass reproduction, he said.

“Most people focus on impacts on bass nests where guarding males have been removed. While no doubt individual nests would be at risk if males were removed, we certainly haven't seen any reduction in bass production in Lake Erie with the combination of spring fishing and gobies.

“I suspect it is the classic question of individual nest threats and lakewide production risk. I'm inclined to think that except under circumstances of extreme spring fishing pressure that we would not likely see any system wide reductions in bass production with gobies.

“Many of the other likely goby activities would very likely be positive to sport fish. Where they occur, both walleye and bass seem to make great use of them, so they would likely represent an additional prey resource that could result in faster growth rates.

“They spawn throughout the summer so there will potentially be a steady supply of small fish prey for young bass and walleye. We know in Oneida that young walleye have had some difficulty remaining piscivorous through the summer due to poor yellow perch production, so gobies might be a benefit to them.

“Double-crested cormorants also like gobies, so gobies could represent an additional buffer for sport fish to cormorant predation. And gobies eat zebra and quagga mussels, which we have plenty of.

“I suppose my primary concern is how gobies might impact angler catch rates. While we don't have great data for bass, we have seen that in Oneida, walleye catch rates are very tightly linked to the abundance of forage for adult walleye, not the numbers of adult walleye. In years when yellow perch produce large year classes, small perch are readily available to walleye and angler catch rates go down.

“In years when perch are rare, walleye catch rates are high. Gizzard shad play a similar role. When they are abundant, walleye can be hard to catch.

“If gobies establish at high densities, they could negatively impact angler catches. So adult game fish may grow faster but anglers won't have as much luck catching them. There is some irony in that gobies could potentially benefit many dynamics of our sport fish but at the same time create conditions where it is more difficult for anglers to benefit from that.”