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Entries in gobies (9)

Thursday
Mar082018

'Left-Handed' Bass?

Two researchers in Japan have discovered that bass are more like bass anglers than anyone would have suspected.

While we are right- or left-handed, a largemouth bass favors one side of its body over the other.

"This antisymmetry is defined as dimorphism in which one side of the body is structurally and/or functionally more developed than the other," explained Maski Yasugi and Michio Hori from Kyoto University.

In other words, some bass turn left more often when moving and feeding and others turn right. And, the researchers learned, the same holds true for other fish, including forage species such as gobies.

That being the case, they wondered, would bass that turned preferentially in one way have more success capturing prey that turned toward or away from them.

Yasugi and Hori filmed encounters between  bass and gobies as the predators approached from the rear. Recording the distance, direction, speed and success of the bass strike, the duo also noted the point during the attack when the goby began to take evasive action and the direction in which it turned.

Finally, knowing that left-biased individuals tend to be more strongly developed on the left side and vice versa, the duo measured the size of the bass lower jaws, looking for the telltale asymmetry that would confirm their directional preference.

As they correlated the bass approach direction with its direction preference, they realized that when approaching from the rear, left-biased bass circled in a clockwise direction, while right-biased bass circled counter-clockwise.

Meanwhile, left-biased gobies reacted earlier to the approach of left-biased bass and right-biased gobies escaped more quickly from right-biased bass. This suggests that right-biased gobies are more at risk from left-biased bass approaching from behind while left-biased gobies are more vulnerable to attacks from right-biased bass approaching from the rear.

"We believe that the lateral biases in approach direction and in evasive response corresponding to morphological antisymmetry are the principal mechanism causing the predominance of cross-predation," Yasugi and Hori concluded.

Practically, this discovery isn't likely to help anglers catch more fish, but it does give them something to think about as they watch bass chase baits to their boats and then turn away at the last second

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.

Thursday
Feb162017

That's Not a Goby . . . THIS Is a Goby!

Fish in the top photo is a round goby, an exotic fish introduced to the Great Lakes in the ballast water of ocean-going ships. They grow to about 6 inches maximum, but 3 to 4 inches is the norm. Also, they have proven to be among the favorite forage for smallmouth bass, and anecdotal evidence suggests that they are growing faster and larger on a goby diet.

Fish in the bottom photo is the world record marbled goby, caught in Thailand by John Merritt. It checked in at 5 pound, 3 ounces. IGFA says that it is "likely the largest of gobies." And with a mouth like that, it likely could turn the tables on some of those smallmouth bass that are eating its smaller, globe-trotting cousin.

You can see more "weird world records" at Sport Fishing.

The International Sport Fishing Association (IGFA) is the official record keeper for both fresh and saltwater species. You can see the full list here. For line class records and additional information, you must become a member.

Wednesday
Jan212015

Ontario's Lake Simcoe Yields 8-Pound Smallie

Dave Chong with 8.05-pound Lake Simcoe smallmouth. Photo by Wil Wegman

Ontario’s Lake Simcoe continues to live up to its reputation as the best smallmouth bass lake in Canada, if not North America. Dave Chong of the Aurora Bassmaster Club earned the latest gold star for the Ontario fishery, as he caught and released an 8.05-pound smallie in late October.

“At first I thought it was a laker (lake trout) because it was so strong and peeled drag seeral times without ever attempting to jump,” said Chong, a veteran tournament angler who was fishing in 27 feet of water with a Lucky Craft Pointer deep diver. “I was not sure what it really was until we saw this gorgeous bass about 15 feet below the boat. I thought it was over 5, maybe 6 pounds.”

Chong knows big smallmouth bass when he sees them, having caught 32 of 7 pounds or more in Simcoe. His previous best was 7.5.

Plenty of other anglers have tangled with hefty bronzebacks there as well. In 2010, Ontario’s sixth largest inland lake yielded a five-bass limit of 31.5 pounds during the Bass Pro Shops Simcoe Open, hosted by the Aurora club. During that same event, an 8.05 also was weighed in. That is believed to be the heaviest bass recorded in a Canada tournament.

What’s going on at Simcoe, a far north lake where the winters are long and the growing season short?

Chong believes forage is the key. The fishery sandwiched between Lakes Huron and Ontario always has offered smallmouth bass plenty to eat, via smelt, herring, emerald shiners, sunfish, and crawfish. But the migration of round gobies into the lake from Ontario seems to have kicked up growth a notch, as it has in other smallmouth fisheries.

“I know that there are double digit smallmouth bass in Lake Simcoe, and believe that the world record will be broken on it one day,” he said. 

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