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Entries in invasive species (184)

Monday
Jan132014

Lake Trout Recovering from Lamprey, Alewife Invasions

Lake trout photo by Robert Montgomery

Good news from Lake Huron, where lake trout seem to be reproducing --- finally.

First, sea lamprey migrated into the Great Lakes from the Atlantic Ocean and nearly obliterated them. Resource managers have managed to minimize the impacts of this blood-sucking invader, with millions of dollars spent on mitigation.

Then the alewife, another exotic species, complicated recovery.  As they fed on the prolific baitfish, lake trout sustained a vitamin deficiency that damaged reproduction. Supplemental stocking by the federal government did little to sustain the population.

But about a decade ago, the alewife population collapsed, probably because an overabundance of predatory salmon, yet another introduced species.

So, with lamprey minimized and lake trout now getting the nutrients they need from native forage, they finally are successfully reproducing and could be on the road to recovery, according to Michigan Radio.

 “I felt we were so completely stymied by one thing after another after another. The litany of challenges working against the reestablishment of a self-sustaining lake trout population seemed insurmountable,” said Jim Johnson of the Michigan Department of Natural Resources.  “But then, with the collapse of alewives, everything changed.”  

Read more here.

Friday
Jan102014

Mussel Threat Grows in West

Unlike zebras, quagga mussels can colonize soft substrates as well as hard surfaces, such as this boat prop.

Out West, resource managers are waging a fierce battle to keep zebra and quagga mussels out of their lakes and reservoirs.  I wish them well, but all it takes is one boat out of thousands launched to infect a waterway.

At Lake Tahoe last year, boat inspectors found 36 vessels infested with exotic species, as they inspected more than 7,000 and decontaminated more than 4,000. Most importantly, though, managers found no evidence of mussels in the lake.

Other fisheries were not as lucky, as a quagga infestation was discovered in California’s Lake Piru, with boat quarantines implemented at Cachuma and Casitas.

By the way, quaggas are even more troublesome than zebras, as they can withstand colder water than their cousins and they can colonize soft substrates.

According to the Great Lakes Echo:

“These abilities have helped it colonize most of benthic Lake Michigan. Just like zebra mussels, quagga mussels are quite effective at clogging water intake pipes and other infrastructure. Mitigating these impacts has cost Great Lakes residents millions of dollars.”

The Echo annually publishes Tim Campbell’s invasive-species rewrite of “The Twelve Days of Christmas, which he created in 2011 for the Wisconsin Sea Grant.

“Twelve quaggas clogging, ‘leven gobies gobbling, ten alewives croaking, nine eggs in resting, eight shrimp ‘a swarming, seven carp and counting, six lamprey leapingFIVE BOAT-WASH STATIONS! Four perch on ice, three clean boat steps, two red swamp crayfish and a carp barrier in the city!”

Friday
Jan032014

Asian Carp Adapt as They Spread East and 'Corps Clueless'

As if Asian carp weren’t a problem before, now they are adapting to become even more of a threat, according to a Purdue University researcher. In an editorial, meanwhile, The Plain Dealer in Cleveland calls the Corps "clueless" about how to stop the invaders. 

From research in the Wabash River (Indiana), Reuben Goforth said that he and his team have discovered that the gills of the invaders are growing stronger, allowing them to thrive in a greater variety of habitats.

“They are not tied to specific water levels like we thought they were,” he said.

Additionally, he revealed that they are spawning more prolifically. Previously, his students had found as many as 1,000 eggs during a five-minute net collection. But in June, they found 300,000 eggs in three minutes. Concurrently, anglers reported seeing a ¾-mile stretch from bank to bank exploding with spawning carp.

“We’ve never seen anything like this before,” Goforth said. “Fish are doing things here that they haven’t in their native distribution, which frankly scares me.”

He added that the adaptations remind him of a line in the movie “Jurassic Park”: “If there’s anything that the history of evolution has taught us, it is that life will not be contained. Life breaks free and expands to new territories . . .”

Meanwhile, studies are underway to develop an Asian carp-specific toxin, which would not affect other species, according to John Goss, Asian carp director for the White House Council on Environmental Quality.

“It could be expensive, but it could be an effective tool in a small area,” he said.

Unless the carp adapt.

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

Monday
Dec302013

'12 Worst Invasive Fish on Earth'

Smallmouth bass. Photos from Environmental Graffiti.

Have you ever seen a largemouth bass eat an alligator? Neither have I.

I’m not saying it hasn’t--- or couldn’t--- happen. Predatory fish are opportunistic feeders and will eat any critter that they can catch and swallow.

Or did you know that largemouth bass “eat day and night.”

I didn’t know that either, and I know plenty of anglers who would disagree with that assessment.

I stumbled upon these two portrayals of largemouth behavior on a list of “12 Worst Invasive Fish on Earth” at Environmental Graffiti.”

In general, I agree with the list, including the inclusion of both largemouth and smallmouth bass. Because they are popular game fish, and because they are so cooperative and adaptable, they have been spread well beyond their original ranges. And they will eat smaller native species.

Common carp

In our own Northwest, however, they are inaccurately blamed for the demise of salmon populations, which have declined because of altered habitat and degraded water quality. While dams have provided perfect reservoir habitat for bass, they have been devastating to cold-water fisheries.

My belief is that the author of this list is either from the Canada or the United Kingdom. His descriptions certainly suggest to me that he’s not an angler and he has no personal experience with either bass species. Here is what he says about smallmouths:

“Even small mammals and snakes aren’t safe! Once this bass has its prey, there’s little chance of escape, as its mouth is lined with tiny gripping teeth that work like Velcro.”

My biggest criticism: Why aren’t Asian (bighead and silver) carp included?

Sunday
Dec292013

Snakes, Bears Make Florida a Dangerous Place to Live

Nationally, the exotic species of most concern are carp, mussels, and plants.

But in Florida, a reptile also is in the mix. It’s an apex predator that gobbling up birds, mammals, and other reptiles in the Everglades.

And as its food supply dwindles and its population increases, the Burmese python will expand its range.  It will go south into the Keys, west toward the Gulf coast, north toward Lake Okeechobee, and east toward the most densely populated portion of Florida.

At the moment, it seems unlikely that the python will migrate too far north. But it’s an exotic species in a new habitat, meaning behavior is unpredictable. Also, winters are moderating. Could it travel all the way up the peninsula and then west along the upper Gulf Coast? It’s possible, although unlikely.

What’s more certain is that the threat to human life will increase, especially in and around Miami. One of the largest snakes in the world, the python can grow to 20 feet in its native Asia, and already has been documented at 16 feet in the Everglades. Such massive reptiles weigh more than 100 pounds

And they can kill and consume human-size meals. Check out this recent report from Indonesia, where a python killed a security guard near a luxury hotel. A few years ago, a “pet” python killed a child in Florida. Earlier this year, two children were strangled by another “pet” in Canada.

Children and pets in Florida are going to be especially at risk in the years to come.

But I no longer believe that the python is the most dangerous species in the Sunshine State. No, it’s not the native alligator either.

I put the black bear at the top of the list. Its population has reached critical mass in the central part of the state, and, sooner rather than later, someone is going to be killed.

Especially in the Longwood area, the bears roam neighborhoods, tear up garbage cans, and try to enter houses. Nevertheless, many lived under the mistaken notion that they could peacefully co-exist with these large omnivores that will gobble up garbage as quickly as they will a pot-belly pig. Some of them still feel that way.

But they are wrong, as evidenced by the attack on a woman out walking her dog earlier this month. More recently, a bear broke into a screened patio, looking for food.

And, yet, the biggest problem is not the black bear. It’s the people. Some continue to feed the animals, despite warnings not to. Others don’t secure their garbage and/or feed their pets outdoors.

Those people who are the most problematic, however, are the bear defenders, those who raised holy hell when the Florida Fish and Wildlife Conservation Commission (FWC) killed two in the aftermath of the attack on the woman, and those who mistakenly believe that they can live in peace and harmony with the bears if all people will just “follow the rules.”

What we’re talking about now in central Florida is a large, aggressive bear population that has lost its fear of humans and has learned that food is most abundant where people live. That food could be the remains of pizza, a dog, or a child. A wild predator doesn’t differentiate.

Of course, the animal apologists argue that their furry friends should be “relocated” to nearby national forests instead of being killed. The problem with that is that those areas already have the maximum population that they can sustain, which is one of the main reasons that bears are roaming suburban neighborhoods. Additionally, bears accustomed to eating from garbage cans and breaking into patios to eat pet food are not going to stay in wild areas; they will return to more civilized dining.

The most logical solution is a managed hunt, which other states, including New Jersey, already utilize as a way of keeping the bear population under check. That’s also the way that we maintain populations of deer, turkey, and other species. If we are going to co-exist with these animals we must limit their numbers because we also have reduced their habitat. It’s that simple.

But you can bet that if the FWC proposes a hunt, PETA and other animal rights groups will descend on Florida like a horde of locusts, delighting in the reality that they will receive nationwide publicity in such a high-profile state.

I don’t envy the good folks at FWC who want to do the right thing, but must figure out a way to manage both the wildlife and the uneducated people who seek to prevent the agency from doing what’s right.

And I am saddened by realization that the only thing that will prompt a rational response to this problem is for someone to be killed. No such easily implemented solution exists for the Burmese python, but it certainly does for the black bear.