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Entries in exotic species (234)

Sunday
Feb182018

Snakehead Movements Across Land Studied

With the help of Maryland Department of Natural Resources, a Ph.D. candidate at Wake Forest University is unraveling the mystery of how northern snakeheads travel across land, from one water body to another.

Noah Bressman said that the fish provided by the agency "make almost the same movements as soldiers." Only instead of crawling by moving a leg and opposite arm as a soldier does, the toothy predator moves its back fin and head in opposite directions to propel it forward.

Thursday
Jan182018

Huge Tilapia Caught In . . . Tennessee?

The Nile tilapia is exotic species from tropical Africa. It shouldn't be able to survive the winters in Tennessee. But in one reservoir, it is. And the fish are reproducing and growing big. Photo shows the state record on rod and reel, 7 pounds. 6.6 ounces. Bow fisherman took one that weighed 9 pounds, 8.4 ounces..

How is this possible?

Remember what mathematician Ian Malcolm said in "Jurassic Park," when scientists told him that dinosaurs wouldn't reproduce because they were all genetically engineered to be female?

"Life, uh . . . finds a way."

Yeah, Tennessee anglers have a new fishery, but what does this say about the possibility--- even the likelihood--- of other exotic species, including piranha, becoming established in places where they shouldn't be able to survive? And this is not the first time something like this has happened. Another tropical exotic is established in a South Dakota stream, believe it or not.

I'll have an conservation feature coming up about this in B.A.S.S. Times and then later at Activist Angler.

Sunday
Dec102017

B.A.S.S., Other Groups Urge Action By Corps To Protect Great Lakes

B.A.S.S., along with other hunting, angling, conservation and outdoor industry organizations, supports the U.S. Army Corps of Engineers’ plan to prevent Asian carp from infesting the Great Lakes.

The Brandon Road Lock and Dam, near Joliet, Ill., and below the Chicago Area Waterway System, is a chokepoint to reduce the risk of invasive Asian carp swimming directly into Lake Michigan. The Corps’ “Tentatively Selected Plan” (TSP) proposes a gauntlet of technologies including an electric barrier, water jets, complex sound and a flushing lock to reduce the risk of Asian carp getting through, while still allowing navigation through the lock.

“Asian carp pose one of the greatest threats to the Great Lakes and the world-class smallmouth bass fishery that anglers travel from all over the country to enjoy,” said B.A.S.S. Conservation Director Gene Gilliland. 

 “The Great Lakes are home to many invasive species. Some of those invaders have been worse than others, but just how many more can the system take before it reaches a tipping point and bad things start to happen? Bass fishermen sometimes don’t recognize invasive species as such a bad thing, especially when you talk about the Great Lakes.

“Zebra mussels and gobies, while real problems for industry and shipping, have proved to be a boon to the bass population, but nothing good can come from an Asian carp invasion. These fish have incredibly high reproductive potential, and in short order, can make up the majority of the pounds of fish a body of water can support. They filter out the plankton that is the base of the food chain for everything else, there are few markets for them and no real way to control the population explosion.”

While expressing support for the TSP, the groups in a letter also urge the Corps of Engineers to pursue full federal funding of the $275 million estimated cost, rather than require a local cost share, due to the national significance of the issue.

Additionally, the groups noted that Congress authorized the Corps to prevent aquatic invasive species transfer between the Great Lakes and Mississippi River basins, and therefore the Corps needs to continue pursuing a two-way solution to preventing aquatic invasive species transfer. However, that pursuit should be simultaneous without diverting resources from moving ahead with the TSP.

“Competing interests and politics-as-usual have stalled the closure of the carp pathway to Lake Michigan for too long,” said Gilliland. “It’s been studied to death, and we know what needs to be done. There is just no more time. This needs to be pushed through, or we stand to lose one of this country's greatest fisheries.”

The groups also encourage the Corps to explore Aquatic Nuisance Species treatment technology that can be used in the locks, as well as continuing other efforts to reduce the Asian carp population below the lock and dam.

The Corps issued a timeline with the release of the plan, which estimates a final report in August 2019, at which point it will be up to Congress to approve and fund the project, with a construction completion date of 2025 if there is no delay in approval and funding.

B.A.S.S. is among 50 conservation and fishing industry groups signing the letter of support. Others include the American Sportfishing Association, Congressional Sportsmen’s Foundation, Ducks Unlimited, National Wildlife Federation and B.A.S.S. Nation organizations in Ohio and Michigan.

Thursday
Nov022017

Round Gobies: The Good, The Bad, And The Ugly

A small invader has had a large impact on some northern bass fisheries since it first was discovered in 1990 in the St. Clair River, and it's not finished yet.

A bottom-dwelling fish that can grow to 10 inches, but more commonly is 3 to 5, the round goby has gained notoriety for eating the eggs of other species, including bass, in the Great Lakes and other waters. But it also has developed a taste for shellfish, it seems, particularly zebra mussels, another exotic species. At a glance, that would seem good news, but not necessarily.

 "In the past two years, we have observed a decline in the total mussel biomass in Oneida Lake, likely because of the rapid growth of the goby population," said Stephanie Roh, a Cornell University student researcher. "If these trends continue, we expect to see lakewide ecological changes such as decreased water clarity very soon."

The implications could be significant. Although zebra and now quagga mussels have caused many problems and cost the nation billions of dollars for control and mitigation, their filter feeding has improved water clarity in many fisheries, allowing more sunlight penetration, and thus encouraging the growth of beneficial vegetation.

In general, that has been good for bass and other sport fish that primarily are sight feeders. In places such as Minnesota's Mille Lacs, however, that ecological change is suspected, along with warming waters, of contributing to the decline in walleye, which prefer darker conditions.

Also, clearer water means less productivity in the form of phytoplankton and zooplankton at the bottom of the food chain for prey fish to eat. "Walleye eat mostly fish, and there's not as many fish," said Minnesota fisheries biologist Eric Jensen, adding that smallmouth continue to thrive because they also eat crayfish.

Still, this potential impact is just speculation at this point.

"We haven't seen that yet, but are still watching things unfold," said Cornell professor Randy Jackson, who has been keeping an eye on how gobies impact Oneida's bass fishery since anglers first reported catching a few of the invaders in 2013.

"It is not my impression from the Great Lakes, where gobies have been established for much longer, that people think that are having a large impact on mussel densities," he said.

What is no longer speculation, however, is that bass, especially smallmouths, seem to grow faster and larger when their diet consists mostly of gobies.

Following a study of the diets for largemouth and smallmouth bass in eastern Lake Ontario, scientists concluded the following:

"Our results provide further support that recent increases in the size of Lake Ontario bass are a result of round goby consumption, and that the effects of this dietary shift on body condition are greater for smallmouth bass."

And from a study on Lake Erie:

"Roundy goby became the dominant prey of smallmouth bass after its invasion (observed in 73.3 percent of diets), and crayfish were only observed in 5.8 percent of diets in the post-round goby time period. Length-at-age increased following invasion of round goby and the greatest increases in length (11 to 15 percent) were observed for ages 2 to 4."

Also,  state record smallmouth bass caught in Michigan and New York during 2016 were taken from waters where gobies are established. In Michigan, the bass from Indian River  checked in at  9.98 pounds, nearly double digits! It bested a mark of 9.33 set less than a year previous. Before that, the state record of 9.25 pounds had been in place since 1906. In New York, a 8.25-pound bronzeback from the St. Lawrence tied a record first established in 1995.

Jackson is not ready to say that's going to happen on Oneida, where gobies still are settling in as permanent residents and all data is preliminary.

"It is our sense that we are seeing some larger, and fatter bass the last couple of years," he said. "But this is anecdotal. Overall it is too early to see significant increases in lengths of bass, but we seem headed in that direction. Anglers also are saying fish are bigger."

One way that gobies could be benefitting bass growth rates and size, he speculated, is that they spawn several times during a season. "With  production of small gobies all season long, I would imagine bass would have no problems remaining piscivorous all summer, which should enhance growth.

"This may be a more subtle, behind the scenes impact of gobies," he continued. "But in systems, particularly in the north, where first-year growth of young bass is important to overwinter survival, enhanced growth could ultimately lead to improved recruitment and increases in adult population size, assuming that population size is not limited by something acting on adults."
And here's another reason to like gobies:

Double-breasted cormorants seem to like them. According to Jackson, they have seem to have shifted to feeding on them in some fisheries, "which, of course, is good for sport fish that they used to eat more of. Our cormorants are starting to eat gobies as well, but we haven't seen a wholesale shift yet. Everyone is hopeful."

 

The Dark Side

Still, predation by sport fish and cormorants on gobies is but one piece of the puzzle on how this exotic fish will ultimately will impact native species and their ecosystems. There are plenty of negatives as well.

Michigan Sea Grant points out that gobies have been linked to outbreaks of botulism, which have killed fish-eating birds around the Great Lakes.  Mussels accumulate the toxin in their flesh, as they filter feed in places where it thrives in water depleted of oxygen by decaying algae.  Gobies eat the mussels, and predatory fish and birds eat the gobies.    

Additionally, the Aquatic Nuisance Species Task Force (ANS) said, "They out-compete native fish for food due partially to an ability to feed in darkness and to the presence of a suctorial disk located on their pelvic fin, which allows them to attach to rocks/substrates and remain fixed on the bottom even in faster currents. Tubenose and round gobies are the only fish to possess this unique characteristic."

It also warns that gobies "maybe interfere with habitat restoration projects. Round gobies are aggressive toward other fish and may drive native fish away from prime spawning areas."

In the St. Clair River, where gobies were first confirmed nearly 30 years ago, populations of native sculpin and logperch have suffered substantial declines.

Friday
Oct272017

Canadians Say Asian Carp Are In Lake Huron

Canadians are saying that they have conclusive evidence that Asian carp now are in Lake Huron. Considering that lake's central location among, that would mean the invaders have easy access  to Lakes Michigan, Erie, and Superior, although the latter might be too infertile and cold for them to thrive there.

Or, if this report is true, carp already could be in Michigan and moved into Huron from there.

Still, this also could be much ado about nothing in terms of the Asian carp that post the greatest threat to the Great Lakes. Those are bighead and silver.

In Canada, grass carp also are commonly referred to as Asian. While they certainly would not be a welcome addition to the lakes, they don't pose the threat to the sport fishery that the other two do. Grass carp feed on aquatic vegetation, which would diminish beneficial fish habitat. But they don't quickly dominate a water body as the other two do.

Bighead and silver, meanwhile, are filter feeders, gobbling up phytoplankton and zooplankton, the base of the food chain for the young of most sport fish, as well important food for shad and other native filter feeders. Also they are prolific, growing large quickly and crowding out other species with their numbers and mass.

Here's one of the Canadian articles about the discovery:

A delegate to last week’s Coastal Municipal Forum says there is now conclusive evidence that Asian Carp are now in Lake Huron.

Dave Myett, a councillor with Saugeen Shores, says the Ministry of Natural Resources has told them they’re able to test the water and determine what kind of fish has passed through by the presence of their DNA. And they say they have found the presence of Asian Carp DNA.

Myett says at this point they can’t tell how many there were or their size. He points out they’re a very elusive species so anyone that either finds a dead one or catches one should notify the ministry.

Myett also points out that given their size and they’ll ability to procreate once they reach a body of water they eventually out eat and dominate other species.

The forum was hosted by the Lake Huron Centre for Coastal Conservation

“We have been led to believe by the Ministry of Natural Resources and Forestry that there is conclusive evidence that the DNA has been detected of the Asian Carp in Lake Huron,” says Myett. “They can test the water at the source points and they can tell what kind of fish has passed through there by telling if the DNA is present in the water.”

“They seem to be an elusive species,” says Myett. “They’re rarely seen on the shoreline or caught. They’re very hard to catch. If someone finally finds a dead one or catches one in a net or fishing, then I’m sure the Ministry would very much like to hear about it.”