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Entries in invasive species (216)


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.


Early Warning System Created for Harmful Algal Blooms

Lake Erie algal boom. Photo by Michigan Sea Grant

Four federal agencies have joined forces to create an early warning system for toxic and nuisance algal blooms (HABs) in the Great Lakes and other freshwater systems.

Harmful algal blooms have emerged as a significant public health and economic issue that requires extensive scientific investigation,” said Suzette Kimball, acting director of the U.S. Geological Survey (USGS).

USGS, U.S. Environmental Protection Agency, the National Aeronautics and Space Administration (NASA), and the National Oceanic and Atmospheric Administration (NOAA) will use satellites to gather color dates from freshwater bodies during scans of the Earth. They then will share the findings with state and local agencies so they can provide public health advisories when needed.

“In addition, the project will improve the understanding of the environmental causes and health effects of these cyanobacteria and phytoplankton blooms in the United States,” NOAA said in a press release.

NOAA added that these blooms are a global problem. “Cyanobacteria (blue-green alga)  is of particular concern because it produces toxins that can kill wildlife and domestic animals and cause illness in humans through exposure to contaminated freshwater and consumption of contaminated drinking water, fish, or shellfish,” it said.

HABs have been on the increase since the mid 1990s, according to Michigan Sea Grant College Program. In the Great Lakes, malfunctioning septic systems, products with phosphates (dishwater detergent) and nitrogen (lawn fertilizers), and urban and agricultural runoff likely have contributed.

“Some scientists also link the increase of harmful algal blooms to the invasion of zebra and quagga mussels in the Great Lakes and the ability of the mussels to filter feed,” Sea Grant said. “Essentially, they eat the good algae and phytoplankton but release organisms like blue-green algae back into the water intact.”

HABs annually cost the nation about $64 million because of loss of recreational usage, additional treatment for drinking water, and decline in waterfront property values. In August 2014, Toledo, Ohio, an algal bloom in Lake Erie forced Toledo, Ohio, officials to temporarily ban consumption of drinking water supplied to more than 400,000 residents.

The new collaborative network will build on previous NASA ocean satellite sensor technologies created to study microscopic algal communities in the ocean, which play a role in climate change, ocean ecology, and the movement of carbon dioxide between the atmosphere and ocean.


New Challenges Face America's Trout, Says TU

America’s native trout have declined dramatically over the last century thanks to a number of threats ranging from hatchery fish stocking to logging and mining to poorly designed roads and livestock grazing practices. Now a new suite of threats, from energy development to a changing climate, poses even greater challenges.   

According to a new Trout Unlimited report titled, “State of the Trout,” these threats are greater than ever, and they make for an uncertain future for coldwater fish if steps are not taken to protect and restore habitat, reconnect tributaries to mainstem rivers and keep native trout populations viable for the benefit of anglers and the country’s riparian ecosystems.

The report notes that, of the nation’s 28 unique species and subspecies of trout and char, three are already extinct. Of the remaining 25 species, 13 occupy less than 25 percent of their native ranges.

Trout across America are dealing with the cumulative effects of resource extraction, climate change and the introduction and persistence of non-native fish into native trout waters. But, according to the report, there is hope for trout and for those who fish for them all across the nation. The report lays out a roadmap for native trout recovery and persistence, but it will require a host of advocates playing vital protection and restoration roles for years to come.

“It’s daunting when you consider the scope of the threats facing coldwater fish in the United States,” said Chris Wood, TU’s president and CEO. “But if you step back and look at the work that TU and our partners are already doing all across the country, it’s encouraging to see progress and to know that, with help from volunteers, private industry, government agencies and elected officials, we can replicate that progress and keep trout in our waters.

“And that’s why this report isn’t just for anglers or for biologists,” Wood continued. “This is a report for all Americans, because trout require the cleanest and coldest water to survive—and we all need clean water.”

Like Wood, report author Jack Williams, TU’s senior scientist, believes all Americans have a stake in this report, and that it will require a collective effort to ensure a future for native trout in America.

“The reasons many populations of native trout are on the ropes is because of our growing human population and the increasing demand on water resources,” Williams said. “For eons, the great diversity of trout genetics and life histories coupled with their widespread distribution allowed them to thrive. The changes we’ve made to their habitat over time, just by pursuing our lifestyle, has had a huge impact on water quality, connectivity and trout habitat. We’ve also stocked non-native trout on top of native populations, to the point where even well-adapted native trout are overcome by repeated stockings.”

Williams notes that common-sense conservation measures in the years to come can help native trout recover. But, restoration needs to take place across entire watersheds and be sustained over decades.

For instance, in Maggie Creek in northwest Nevada, collaborative restoration has been underway since the late 1980s. TU’s work with ranchers, the Bureau of Land Management and mining companies have restored 2,000 acres of riparian habitat and today native Lahontan cutthroat trout have been completely restored in 23 miles of Maggie Creek and its tributaries.

In Maine, where TU and its partners helped negotiate the removal of two dams and construction of fish passage on a third, more than 1,000 miles of the Penobscot River has been reopened to Atlantic salmon, striped bass, herring and shad.

In the West, in states like Idaho and Colorado, sportsmen and women have mobilized and helped protect millions of acres of intact, functional habitat that is vital to trout and the waters in which they swim. Broad-scale restoration work on streams in the Driftless Area of the Midwest has translated into waters that once held only 200 fish per mile to holding 2,000 fish per mile.

TU’s public and private partners are key to the report’s findings. Without help from government, private entities and volunteers, trout truly do face an uncertain future.

"The health of America's trout is directly connected to the health of our nation's watersheds—watersheds that provide clean drinking water, drive economic growth and support recreational fishing opportunities for millions of people across the nation," said U.S. Fish and Wildlife Service Director Dan Ashe. "The ‘State of the Trout’ report provides a valuable overview of the health of these fisheries, helping Trout Unlimited, the Fish and Wildlife Service and our partners identify priority areas for conservation."



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.)


Monster Silver Carp Suggests Nightmarish Future Awaits Anglers, Native Species

What will happen to fisheries nationwide and even to outdoor recreation in general as Asian carp continue to spread, reproduce, and outcompete native species? We’ve just received a glimpse of a nightmarish possibility from Kentucky Lake, where angler Bill Schroeder foul-hooked and landed a 106-pound silver carp.

Although I’ve been unable to confirm it, I suspect that’s the largest silver carp taken in the United States, and possibly even the world. Experts say maximum weight for the exotic fish is about 60 pounds. And even now, the Tennessee state record for the silver carp, caught in 2013 on Kentucky Lake, was just 14 pounds, 13 ounces.

What’s going on? Silver carp like it here. So do bighead carp. Typically a larger fish, its maximum weigh is about 90 pounds. But in 2011, an angler targeting paddlefish hooked and landed a 106-pound specimen at Lake of the Ozarks.

And the exotic lionfish likes it here too. As it spreads all across the Gulf of Mexico and up the Atlantic coast, anglers are catching larger and larger specimens of this voracious predator. In its native range, it grows to 12 to 15 inches. Just a few days ago, one was caught off in the Florida Keys that measured nearly 19 inches.

Why are these exotics growing to horror-movie size proportions in our waters? Because they are exotic species, they have no “natural” predators, as they do in their native ranges. And they’re feasting on an abundance of food in our relatively fertile and healthy waters. By contrast, Asian carp struggle to survive in their native range because of pollution and overfishing.

Will the same happen with the Burmese python in the Everglades? Introduced to the wild by an irresponsible and little-regulated pet industry, it is now gobbling up native mammals and reptiles, and likely will expand its range into more developed areas. Will it grow to unprecedented size as well?

Now consider this: Asian carp are schooling fish. Frightened by disturbances on the surface, silver carp often go airborne, striking and injuring anglers and other boaters.

But the fish we see in videos of these airborne attacks usually weigh no more than 10 or 15 pounds. Imagine dozens of 100-pound silver carp taking flight all around you as you motor to your favorite fishing hole.

Of course, no one thought about such possibilities when the carp were imported by aquaculture facilities during the 1970s. And it wasn’t until the 1990s that we really started worrying about them crowding out native species in our rivers.

And then there’s the snakehead . . .