My Facebook pages

Robert Montgomery

Why We Fish

Fish, Frogs, and Fireflies

Pippa's Canine Corner 



(adsbygoogle = window.adsbygoogle || []).push({});
(adsbygoogle = window.adsbygoogle || []).push({});
(adsbygoogle = window.adsbygoogle || []).push({});
(adsbygoogle = window.adsbygoogle || []).push({});
Get Updates! and Search
No RSS feeds have been linked to this section.





Entries in fish behavior (4)


Bass Learn And Remember

Bass remember. That's something that anglers should remember when they continue to throw the same baits in the same waters with diminishing returns.

In a laboratory test at Pure Fishing, Inc., Dr. Keith Jones, one of the country's foremost experts on bass behavior, allowed fish to freely strike a minnow lure for 5 minutes. By the end of that time, the bass had learned to ignore it "since it provided no positive food reward."

Half of those fish then were re-exposed to the same lure two weeks later. This time, the interest in the lure was just 1/10th of what it was originally, "indicting that the bass had retained a strong negative memory of the bait during the two-week interval."

After two months, the other half of the fish still tested well below the original response level.

"The results show that under some circumstances, bass can remember lures for at least up to 3 months and perhaps much, much longer," Jones said.  "Who knows? If the experience is bad enough, they might never forget."

Concurrently, Jones discovered that bass learn in four main ways:

  • Associative learning or, in other words, trial and error, which likely is why bass ignored the minnow lure the second time. Also, this type of learning has been proved in lab tests "where the animal is taught to link two types of stimuli, such as certain colored light with an ensuing electric shock. Bass readily learn those associations, both in the lab and in the field, although not as fast as some other species."
  • Habituation. In this type of learning, a bass gradually becomes less sensitive to particular stimulations, such as the noise of boat traffic on a busy lake.
  • Spatial. Bass learn to navigate freely in home environments, recognizing landmarks or objects and staking out territories. Jones reported that bass in a lab learned to find their way through a maze to a desired point.
  • Prey images. Bass learn to recognize different types of forage. "Given enough positive experience with a certain prey type, a bass will gradually come to actively seek out that specific prey," he Jones said. "Prey species, for their part, often counter the bass's efforts by changing their signature stimuli, often through the use of camouflage."

Changing atmospheric pressure is not as likely to affect fish behavior in rivers and streams as it is in lakes and impoundments. That’s because water flow in these fisheries is a more dominating factor for increasing or decreasing pressure than is the air.

One of many "secrets" in Better Bass Fishing: Secrets From The Headwaters By A Bassmaster Senior Writer. Available at Amazon and Barnes & Noble.


BUFFALO, N.Y. — Human antidepressants are building up in the brains of bass, walleye and several other fish common to the Great Lakes region, scientists say.

In a new study, researchers detected high concentrations of these drugs and their metabolized remnants in the brain tissue of 10 fish species found in the Niagara River.

This vital conduit connects two of the Great Lakes, Lake Erie and Lake Ontario, via Niagara Falls. The discovery of antidepressants in aquatic life in the river raises serious environmental concerns, says lead scientist Diana Aga, PhD, the Henry M. Woodburn Professor of Chemistry in the University at Buffalo College of Arts and Sciences.

“These active ingredients from antidepressants, which are coming out from wastewater treatment plants, are accumulating in fish brains,” Aga says. “It is a threat to biodiversity, and we should be very concerned.

“These drugs could affect fish behavior. We didn’t look at behavior in our study, but other research teams have shown that antidepressants can affect the feeding behavior of fish or their survival instincts. Some fish won’t acknowledge the presence of predators as much.”

If changes like these occur in the wild, they have the potential to disrupt the delicate balance between species that helps to keep the ecosystem stable, says study co-author Randolph Singh, PhD, a recent UB graduate from Aga’s lab.

"The levels of antidepressants found do not pose a danger to humans who eat the fish, especially in the U.S., where most people do not eat organs like the brain," Singh says. "However, the risk that the drugs pose to biodiversity is real, and scientists are just beginning to understand what the consequences might be."

"Fish are receiving this cocktail of drugs 24 hours a day, and we are now finding these drugs in their brains." --- Diana Aga

Aga has spent her career developing techniques for detecting contaminants such as pharmaceuticals, antibiotics and endocrine disrupters in the environment.

This is a field of growing concern, especially as the use of such chemicals expands. The percentage of Americans taking antidepressants, for instance, rose 65 percent between 1999-2002 and 2011-14, according to the National Center for Health Statistics.

Wastewater treatment facilities have failed to keep pace with this growth, typically ignoring these drugs, which are then released into the environment, Aga says.

Her new study looked for a variety of pharmaceutical and personal care product chemicals in the organs and muscles of 10 fish species: smallmouth bass, largemouth bass, rudd, rock bass, white bass, white perch, walleye, bowfin, steelhead and yellow perch.

Antidepressants stood out as a major problem: These drugs or their metabolites were found in the brains of every fish species the scientists studied.

The highest concentration of a single compound was found in a rock bass, which had about 400 nanograms of norsertraline — a metabolite of sertraline, the active ingredient in Zoloft — per gram of brain tissue. This was in addition to a cocktail of other compounds found in the same fish, including citalopram, the active ingredient in Celexa, and norfluoxetine, a metabolite of the active ingredient in Prozac and Sarafem.

More than half of the fish brain samples had norsertraline levels of 100 nanograms per gram or higher. In addition, like the rock bass, many of the fish had a medley of antidepressant drugs and metabolites in their brains.

Evidence that antidepressants can change fish behavior generally comes from laboratory studies that expose the animals to higher concentrations of drugs than what is found in the Niagara River. But the findings of the new study are still worrisome: The antidepressants that Aga’s team detected in fish brains had accumulated over time, often reaching concentrations that were several times higher than the levels in the river.

In the brains of smallmouth bass, largemouth bass, rock bass, white bass and walleye, sertraline was found at levels that were estimated to be 20 or more times higher than levels in river water. Levels of norsertraline, the drug’s breakdown product, were even greater, reaching concentrations that were often hundreds of times higher than that found in the river.

Scientists have not done enough research yet to understand what amount of antidepressants poses a risk to animals, or how multiple drugs might interact synergistically to influence behavior, Aga says.

Wastewater treatment is behind the times

The study raises concerns regarding wastewater treatment plants, whose operations have not kept up with the times, says Aga, a member of the UB RENEW (Research and Education in eNergy, Environment and Water) Institute.

In general, wastewater treatment focuses narrowly on killing disease-causing bacteria and on extracting solid matter such as human excrement. Antidepressants, which are found in the urine of people who use the drugs, are largely ignored, along with other chemicals of concern that have become commonplace, Aga says.

“These plants are focused on removing nitrogen, phosphorus, and dissolved organic carbon but there are so many other chemicals that are not prioritized that impact our environment,” she says. “As a result, wildlife is exposed to all of these chemicals. Fish are receiving this cocktail of drugs 24 hours a day, and we are now finding these drugs in their brains.”

The problem is exacerbated, Singh says, by sewage overflows that funnel large quantities of untreated water into rivers and lakes. In August, for example, The Buffalo News reported that since May of 2017, a half billion gallons of combined sewage and storm water had flowed into local waterways, including the Niagara River.


Bass or Carp, Which Species Is Smarter?


If you're an angler who believes that sometimes you get "outsmarted" by those wily ol' bass, I have some bad news for you.

Carp are even "smarter." That's right.  The bottom feeder disrespected by so many is no dummy.

"From my years of experience in observing bass in the laboratory, I would have to rank them around the middle of the intelligence range: definitely smarter than trout (at least hatchery trout) but dumber than carp (no insult intended — carp are smarter than you think!)," said Dr. Keith Jones, who has long studied fish behavior for Berkley.

*    *    *    *

"The common carp (Cyprinus carpio) are indeed among the smartest freshwater fishes, if not THE smartest," said another source. " They learn well for fish. They have the longest complex learning retention of all fishes tested."

Seriously, though, it's impossible to measure fish "intelligence" in any way comparable to the way that it is measured in humans. Rather, we watch how they behave in nature, and, more importantly, in laboratories and just their response to various stimuli.

As I reveal in Better Bass Fishing, you’re just outsmarting yourself if you try to “out-think” bass. Yes, bass are capable of learned behavior. But they definitely aren’t the “Einsteins” of the fish world. Carp and bluegill rank higher in laboratory tests. Most importantly, though, bass (and other fish species) don’t “think” and they aren’t “smart.”

Rather, bass are selective as to food, cover, and water, and, each spring, they are driven by the biological imperative to spawn.

Those anglers who are smart enough to recognize those needs and respond accordingly, are the ones who catch the most and largest bass.  They look for water and cover that they have learned is attractive to bass during each season of the year. They learn the migration routes that fish take to those locations. They observe what bass are feeding on and try to offer baits that are similar in appearance.

Although bass are not smart, they do seem to learn to avoid some baits. That why new baits--- and new colors, to a lesser degree--- seem to produce better than older styles. For a while. We saw it happen with buzzbaits in the 1980s and soft jerkbaits in the 1990s. Now, it's happening with swimbaits.

(Check out all my books here.)

*    *    *    *

And here's an interesting take from the World Fishing Network:

The IQ of fish varies greatly depending on the species. It varies even further depending on individuals within any given species. Anglers need to look at the species that they are targeting for known traits and advantages that could make them more difficult to catch.

Fish can learn to avoid specific lures and noises made by anglers. In order to continue to be successful, anglers need to try new lures and colors on a regular basis. An effort should also be made to fish new areas and to make as little noise as possible.

Fish intelligence is hereditary and they can be bred to be easier to catch. Anglers should care take when harvesting fish in order to avoid selectively breeding intelligence. Smaller fish, whether intelligent or not, haven't had the chance to learn to avoid lures. Therefore, they make a better choice for harvesting.

Whether you are catching fish or not, it is unlikely that they are outsmarting you. Their intelligence is very limited. You just need to work around what they may have learned.

Where do carp and bass rank in intelligence on a planet with more than 30,000 species of fish in our ponds, lakes, rivers, and oceans? We'll likely never know that.

But some scientists suspect that the top of the class are of the marine variety.

"In general, cartilaginous fishes (sharks, skates, and rays) have higher brain-to-body mass ratios than bony fishes, as well as most cold-blooded vertebrates. And manta rays have the largest brain size of any cartilaginous fish, although we don't know why," reports one website.

"What we do know, though, is that they're very curious. They also somehow perceive humans as 'special.' Along with marine mammals, they are among the very few animals known to seek out human contact for reasons other than food. Some of them have even been known to let humans ride on them. Preliminary evidence even suggest that they could recognize themselves in mirrors, putting them in an extremely small group of animals."

And Thom Demas, curator of fishes at the Tennessee Aquarium shared this interesting observation on the same site:

"I don’t know that there is a clear answer to this question but here is a personal experience from my time working with fishes.  The common hogfish, Lachnolaimus maximus, has proven over the years to be a very aware and observant fish. 

"I have kept many of them and while I have never looked into brain to body percentage for this animal, it clearly displays behavior that seems just a bit above that of many other fish I have worked with

"From observing my daily work (the hogfish was doing the observing) to following me around (moving in the tank to be nearest me--- presumably because of curiosity).  I know, you think it probably just wanted food and that’s what I thought. 

One day I fed the fish until it would no longer eat and then went back to my work.  I recall seeing that fish follow me around with a piece of food hanging from its mouth and more on the bottom of the tank being ignored; that convinced me there was more going on. 

I had one that would allow you to 'pet' it while on SCUBA in the water with it.  Many fish are evolved to display lots of complex behaviors or accomplish many things we could interpret as smart but the common hogfish will always be one of the smartest fish in my book!"