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Posts: 1291
Location: Hayward, Wisconsin | University of Eastern Finland
Press release, 28 October 2014
Fish "personality" linked to vulnerability to angling
Individual differences in moving activity in a novel environment are linked to individual differences in vulnerability to angling, according to an experimental study completed at the University of Eastern Finland and the Finnish Game and Fisheries Research Institute. The study used novel, long-term observations of individual behaviour in groups and authentic angling trials to analyse if behaviours predict the vulnerability to fishing in brown trout reared in traditional and enriched hatchery rearing environments. Based on the results, it can be predicted that fishing modifies the heritable behavioural traits of fish by favouring cautious fish. The study was carried out in the Paltamo Unit of the Finnish Game and Fisheries Research Institute. Earlier research has shown that fish in heavily fished populations reach sexual maturity earlier and also grow slower than their ancestors.
This new experimental study discovered individual differences in the behaviour of brown trout transferred to semi-natural stream environments. The differences discovered especially in the exploratory behaviour of the fish soon after the transfer were linked to vulnerability to fishing in an experimental fishing setting. In the experiment, brown trout were fished by angling from ponds with different fish densities.
The more active the brown trout were to explore new environments in the behavioural test, the more vulnerable they were to fishing. However, fish body size or individual differences in swimming activity during the entire experiment were not linked to vulnerability to fishing. Individuals that did not learn to eat the natural food items present in the seminatural behavioural test channels during the long behavioural test and whose condition weakened during the test were more vulnerable to fishing than individuals that remained in good condition. The probability of brown trout to be caught grew as fish density in the experimental ponds increased.
In enriched hatchery rearing, ponds are modified to resemble natural environments more than in traditional hatchery rearing: Ponds have structures providing the fish with shelter, and water levels and current speeds and directions are altered at irregular intervals. Furthermore, feeding takes place according to an irregular schedule. Brown trout reared in traditional environments were more active to explore new surroundings than fish reared in enriched environments, and this behaviour also makes them more vulnerable to fishing. It was also observed that during the experiment, brown trout reared in enriched environments were better able to make use of the natural nutrition available in the semi-natural streams in order to maintain and even improve their condition. The condition of fish reared in traditional environments, on the other hand, weakened during the experiment.
According to the study, the introduction of natural elements to fish hatcheries enhances the later survival of fish released into the wild, as fish grown in enriched environments learn to find food and avoid fishing more often than fish reared in traditional environments.
The study was published electronically in Canadian Journal of Fisheries and Aquatic Sciences: http://www.nrcresearchpress.com/doi/abs/10.1139/cjfas-2014-0221.
For further information, please contact:
Laura Härkönen, University of Eastern Finland and University of Oulu, tel. +358503436 918, laura.harkonen(at)oulu.fi
Anssi Vainikka, University of Eastern Finland, tel. +358505695538, anssi.vainikka(at)uef.fi
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Posts: 284
Location: Eagan, MN | "Based on the results, it can be predicted that fishing modifies the heritable behavioural traits of fish by favouring cautious fish."
Isn't this supportive of what we were discussing in a previous thread?
Very interesting topic to me.
Brian |
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Location: Black Creek, WI | Well then.... you had better enjoy the initial year stockings in Vermilion before they are gone and replaced by the highly intelligent/elusive "next generation".   |
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| BrianF. - 10/28/2014 3:17 PM
"Based on the results, it can be predicted that fishing modifies the heritable behavioural traits of fish by favouring cautious fish."
Isn't this supportive of what we were discussing in a previous thread?
Very interesting topic to me.
Brian
The statement itself is supportive of the theory in the other thread, but I'm not so sure this study actually proves it. I tried the link, but the study is no longer there.
Based on the synopsis in the press release it seems the study actually highlights how the fish behaviour or "personality" (ie. susceptibility to angling) is shaped by environmental conditions during the rearing process. In this study fishing is not being studied as the cause of fish behaviour, but used as a sampling tool to compare the differences between the two populations susceptibility to angling, based on the rearing environment.
As far as angling changing fish behaviour, most anybody who fishes pressured waters will probably agree. I'm sure individual fish can learn avoidance behaviour toward baits that they see a lot and have had negative experiences with. I'm not so sure it would extend to a genetic level that creates less aggressive fish though. More likely offset by the advantages of aggressive behaviour in terms of dominating prime feeding and breeding habitat. As a top of the food chain predator a certain level of aggressiveness is required for survival. More so in environments where food is scarce, or increased competition due to high predator density. The fish have the risk vs reward decision. Ours is action lakes vs trophy waters. 
Edited by Dog Lake 10/28/2014 7:38 PM
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| It's my recent understanding that fish/muskies can't make simple decisions as that would require thought or thinking at even a most basic level of which, I've read on this forum, fish are supposedly not capable of. Therefore, they must be action, reaction only creatures. Thus no risk vs reward decision is possible. |
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| I hear you. However, aren't muskies an ambush predator? If so, they must be able to reason/think at a basic level (e.g. They must be aware of the fact that by laying in wait, they are more likely to be successful hunters - possibly reinforced by past success?). I am not saying that muskies are extremely smart, just that they are probably capable of making very simple decisions. If they are simply a reaction only fish, then why do they often just follow lures and not strike? They must use their brain to think at a basic level. Or at least that is what I would like to believe. |
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Location: Eagan, MN | "The more active the brown trout were to explore new environments in the behavioural test, the more vulnerable they were to fishing."
If muskies are like the trout studied in this test - and I think they are in many ways - then this would seem to collaborate my own experience with muskies first moving up onto spots. That is, they are most vulnerable when they first arrive. Don't miss that first - and often best opportunity - because the longer that fish is up on that spot, exposed to angling, the harder they seem to be to catch. We tend to see more willing fish when they first arrive on spots when establishing their summer home ranges and then again when the summer home ranges breakdown in the fall and the fish begin to move in anticipation of specific fall foraging opportunities. I think Larry's work tracking muskies was the first to unlock some of these movements?
Muskies are 'dumb'. I hate this saying and think its a cop out because relative to humans, yes, they are dumb. However, the statement does little to help us understand the complex behavior that they show as fish, much of which is unseen and unknown to us fishermen. I think that they learn avoidance behavior has been proven, call that what you want. Fish have long term memory that serves them well, with fish making annual seasonal movements in anticipation of very specific foraging opportunities. Muskies seem to have a social aspect to them which is little understood. Certainly, they aggregate and move in groups, generally of like-size individuals. They also learn or perhaps inherit various foraging strategies, including disabling their prey by running them down from behind, focusing their strike at the tail of their prey to disable their locomotion as has been documented on video with Barracuda, from which muskies are believed to have evolved. Most of us have experienced those dreaded tail nippers. That is not necessarily a 'miss' by the musky.
I could go on, but suffice it to say that this is a fascinating and, I think, relatively little known fish. My desire is to understand them better, not only to satisfy my own curiosity, but also to help me become a better musky angler. To agree that they are dumb, and leave it at that, does little to forward our understanding of the fish we seek.
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| fin_prof -science is not absolute. it evolves too.new discoveries change what was widely accepted as" how it is" by science all the time . Eg; the age of the earth debate. i believe it is 4.5 billion years old now? 20-30 yrs ago it was 3 billion yrs old. before that 2.5 billion...What will be the widely accepted age 20 years from now?
What we accept as what fish know now will certainly be different 20 years from now.
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Location: Black Creek, WI | I think Dog Lake has the right idea... or interpretation. The article focused on the impact of rearing pond ENVIRONMENT and its impact on the fish behavior.
There was also a telemetry study done in IA that clearly showed that muskies changed their feeding habits based on environmental changes. The majority of muskies were open water prowlers in the basin in June. However, once weed growth peaked in August these same fish moved into the cover and set up in AMBUSH locations to feed (as theorized by the study author).
It seemed to me that the study Larry posted here was suggesting that fish reared in ponds with little or no natural cover were more likely to roam freely in the lake/river they get stocked into... making them more vulnerable to angling.
If that is the case, I would think that most anglers would NOT want the DNR to create natural environments in the rearing ponds... as most anglers want the "easy" fish in their lakes. This, however, may limit the trophy potential of those fish as they may perish prematurely from excessive angler contact during they lifetime?
Fun stuff to ponder as we approach the winter season... |
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Location: Black Creek, WI | BrianF. - 10/29/2014 7:24 AM
"The more active the brown trout were to explore new environments in the behavioural test, the more vulnerable they were to fishing."
If muskies are like the trout studied in this test - and I think they are in many ways - then this would seem to collaborate my own experience with muskies first moving up onto spots. That is, they are most vulnerable when they first arrive. Don't miss that first - and often best opportunity - because the longer that fish is up on that spot, exposed to angling, the harder they seem to be to catch. We tend to see more willing fish when they first arrive on spots when establishing their summer home ranges and then again when the summer home ranges breakdown in the fall and the fish begin to move in anticipation of specific fall foraging opportunities. I think Larry's work tracking muskies was the first to unlock some of these movements?
Brian
So... TIMING is a critical element for success? Wouldn't it just be easier to stock lakes with "dumb" fish? |
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Location: Eagan, MN | Jason, you don't understand what I'm saying, do you. Brian
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Location: Hayward, Wisconsin | Note: Moderators...don't panic. Just something for the boys to ponder on...
How about a bit of a different take on this...whether it be in an original Minnesota lake or one of the newer stocked ones, the Mississippi strain muskies just plain grow fast in length vs. Wisconsin inland strains. That is why they don't spawn until they are 38-42 inches long...they are still only five years old! WI strain also mature around five years old, but they are about 10 inches shorter.
My take on this is that it is because they grow longer faster, MS strain muskies HAVE to eat more and therefore are more prone to hit a lure and get caught. In the newer lakes where they dumped thousands into, the year class competition was even greater than in the original lakes, ergo, more fish feeding heavily and getting caught.
It is, in my opinion, in MS strain muskies, a genetic development over thousands of years, helped in evolution by Sympatry (competition) with Pike, whereas the WI inland Allopatric strain had no such competition and therefore no need to grow to the sizes of MS strain.
It should also be noted also that the MS strain (and Great Lakes strains) produce two to four times the number of eggs as WI inland strain. Again, likely an evolutionary development to combat competition with Pike, as is this strain spawning offshore in deeper water than WI inland strain muskies.
Bottom line, no matter what stocking manipulations WI does inland, this strain will NEVER produce the number and sizes produced by the other noted strains. IMHO |
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Location: Black Creek, WI | My take so far:
BrianF revealed a nugget of knowledge suggesting the biggest fish in a system relocate first (seasonal movements)... and are most vulnerable to capture upon first arrival to those new locations.
LarryR suggests that the MS Strain and Great Lakes strains are superior in regard to growth potential (and theorizes why).
So, if an angler wants to catch super huge fish... he should target systems containing spotted strain muskies (MS and Great Lakes) and time his efforts with the onset of seasonal movements.
Sounds easy enough.... |
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Posts: 173
| Quite interesting but seems to me Larry R reaches some conclusions influenced by his desire to see Minnesota fish stocked in Wisconsin.
A few observations from other studies : Leech lake fish appear to be latitude specific [ do well at the latitude they developed or farther north but less vigorous growth with southerly stocking . Very common result for life forms .]
The more we know about muskies the more we should realize how little we do know. [ like ascorbic acid levels influence development of the snub nose muskies ]
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Location: Eagan, MN | I agree that there is a lot we don't know. The problem is that the economics don't exist today to fund the study of muskies the way we'd like. So, we're stuck with extrapolating studies of other fish, the limited musky research that IS available, and our own experiences and observations. At some point, we have to connect the dots ourselves, even if we might go down the wrong path for a while.
Edited by BrianF. 10/29/2014 11:40 AM
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Posts: 173
| Additionally , even "IF" funds were available studies of low density are unreliable. Conclusions are drawn based on very few individuals that may or may not be "typical".
Back in my younger years we did some work on deer density . Farmers were unhappy with densities less than 3 per square mile while hunters expressed dissatisfaction with densities over 40 per square mile. General consensus is "stakeholders" are the least reliable source for biological information .
Being fortunate to spend some time with field biologists researching muskies in Canada I try to look at all factors that might impact what we "think" we are seeing. Addicted to reading research papers no matter what the fish or location. I believe it's sound to believe seemingly minor chemical differences in the water can have huge impact. [ look at male/ female ratio changes due to contraceptive chemicals in various systems] .
I find the Baltic pike research amazing. Would never have guessed sex ratio in such a large population would change drastically with implementing a slot limit.
One belief I hold, that could well be due to limited inputs, is stocking fingerlings/ yearlings of muskies fails to create a reproducing population because of chemical imprinting of water chemistry at the fry stage. [ adults seeking that "home" water to spawn in] I think the group spawning with many males to a single female we witness in stocked systems is not the natural process we see in native populations of spawning pairs. [ thus my thinking Green Bay won't be naturally sustaining without fry stocking in "good" spawning habitat] |
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| Nmmusky: I don't know what your comment was trying to convey.
I totally disagree with what you said. science is absolute. We may not always understand and interpret the data and relationships correctly, but the science is absolute. The earth has an exact age. We don't know what it is for certain, but it's age is absolute.
We only know what we know now. I have an opinion today, based on what I know today. I reserve the right to change my opinion if new information comes out. Isn't that implied anytime anyone voices an opinion? I was just voicing an opinion, based on what I know about muskies today. |
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Location: Rhinelander, Wisconsin | Great discussion topic, Larry.
fin_prof - 10/29/2014 12:02 AM
I hear you. However, aren't muskies an ambush predator? If so, they must be able to reason/think at a basic level (e.g. They must be aware of the fact that by laying in wait, they are more likely to be successful hunters - possibly reinforced by past success?). I am not saying that muskies are extremely smart, just that they are probably capable of making very simple decisions. If they are simply a reaction only fish, then why do they often just follow lures and not strike? They must use their brain to think at a basic level. Or at least that is what I would like to believe.
Still loading up on anthropomorphism.
Study stimulus/response. Lose the 'avoidance of a presentation/lure/bait' concept as an 'experiment' (please humor me, in other words), and employ the concept 'adapt to the increasing or steady presence of' and you may be closer to understanding what's happening to the bite in pressured muskie waters.
Every living thing has to adapt to changes in the surrounding environment. No fishing for muskies. Then more. Then MORE. Then LOTS. A double ten first time by and only one in range....then the 110,000th time by and 29 in range.
Remember sound and vibration travel 16 football fields per second underwater, and travel much more distance, too. And remember a lure sounds, behaves, and looks like absolutely NOTHING in nature. To you it does in the air, but study the thing under the surface and compare it to what it's supposed to 'imitate' and it's hilarious to imagine a fish would try to eat the stupid thing.
Don't try to understand how the fish's brain works by comparison to any thing but another fish, best compared to the same species to avoid making assumptions that exclude major physiological differences and much more.
'Long term memory' included, that's somewhat a misuse of the term, but easier to understand as arm chair biologists..so I get the use, but be cautious.
Remember that link on the book I recommended in another thread? Still recommended. Great reading!
Comparing trout behavior to muskies for the purpose of extrapolation probably is not a good idea, there are major physiological differences between the two and big difference in how the two fish feed, interact with members of the same specie, etc. Just the difference in the two fish's vision is a deal breaker.
'It's the fish' all over again. Been there and done that. Read it in the archives, pages and pages and pages. It was and still is a great debate, and the jury is still out, but not for much longer. |
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Location: Hayward, Wisconsin | ).
Back to the discussion: Could it be that muskies can often be coaxed into hitting a lure, especially in a figure 8 because they behave a lot like a cat? Lazy figure 8's usually get followed, but speed up in the turn and "take it away" from them and very often they will hit!
As for other times, if it doesn't "look" like food to them I can't imagine why they hit the darn things (lures), but they do...perhaps in the case of speed, they don't have a chance to realize it isn't food and just react???
Yep, definitely lots of "food for thought" here. |
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| Larry, not to oversimplify the discussion, but to your last question:
Muskies really only have one purpose most of the year. EAT. Over 10,000+ years of evolution, anything that moves in the water and fits down their yap has been edible. Pressured fish certainly become acclimated to the presence of lures. I don't think anybody can argue with that. But they're programmed to eat. And when nature tells them it's time to eat, you can't stop them.
My thinking is that when you see a following fish, that fish would have eaten your lure already if it was "actual" prey. It doesn't look like food or act like food or sound like food. But it's there moving through the water. We're just not effectively invoking that feeding response until we make that "escape move". Again, 10,000 years of evolution at work here. Their prey tries desperately to escape. This is why changes of speed and direction are effective. It's exactly what their food does in an attempt to avoid being eaten. That's why speed is effective. It's getting away!
To Steve's comment, absolutely. They know your lure is there. And on pressured waters, they have adapted to the constant barrage of double 10's all around, morning noon and night. That's why you'll often find the guys doing something different are the ones who caught the fish today.
Luckily for us, none of this is inheritable. While more aggressive fish might be more prone to angling related mortality and harvest, most of what we catch goes right back in the water.
Sooo. How to approach pressured fish? The biggest key is to be out there when nature tells them to eat. Solunar influence, changes in wind speed, direction... I think we'd all be wise to pay careful attention to changes in barometric pressure as well.
Seasonal migration is also huge. Our best weeks have been during those transitions from weeds to rocks in the summer, especially when you have unstable weather that pushes them back and forth from day to day. And then again in the fall.
And yes, a few weeks after that transition, they seem to be more difficult to catch. So timing is critical. Triggering strikes is critical. Knowing where the fish are and where they were before that is critical. Finding warmer water in the fall and cooler water in the summer is critical. Understanding the entire food chain is critical. Putting all the pieces together on a regular basis is the challenge. |
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Posts: 173
| ....and more food. Several of you know Danny Columby that guides on Lake Nippeeing . Read his blog about walleyes and spiny water fleas. Could the spread of invasive species be altering locations muskies are using at formerly predictable times ?
I see the figure 800 quadrillion tons of quaggas and zebras in the Great Lakes. That's a lot of calcium removed from the water. |
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| Larry, will you talk some more about your thoughts on stocked fish and reproduction as it relates to water chemistry?
Perhaps in another thread?
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Posts: 173
| Sure Jeff! Just about to head out for a trip so I'll be brief, for now. With more time I'll put links up for you. If you have time Google " Baltic Sea Pike Research"and the studies regarding pike spawning in certain areas and the chemical composition noted both in the waters and in the fish itself.
Briefly : although the pike comingle out in the sea groups with different composition spawn only in the stream of their birth. Since pike are similar to muskies ,and we know beyond doubt that salmonoids return to their birth [or fry stocked] stream to spawn it "seems" reasonable muskies "might" have a similar function. Could explain why so many stocked populations fail to reproduce.
Another study in Ontario concerns walleye "groups in a stocked system. If I recall correctly the source stocks were from four separate lakes. Each genotype spawned in it's own area of the stocked lake with no intermingling at spawning. [ Admittedly not enough to reach a conclusion].
One other thought before I head out the door: I know of one muskie "pair" that has used the same small area to spawn each of the last eight years. The female is easy to ID being blind in both eyes.
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Location: Rhinelander, Wisconsin | Location/concentration
Just two variables in this 'transition' discussion to consider. There are lots more, not the least of which is the average activity level of the fish in transition VS 'staged' fish. |
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| sworrall - 10/30/2014 11:26 PM
Location/concentration
Just two variables in this 'transition' discussion to consider. There are lots more, not the least of which is the average activity level of the fish in transition VS 'staged' fish.
I'm going to go out on a limb here...
It seems to me that the larger fish are generally more migratory than the smaller fish. When the big fish start moving out past their spawning grounds into the adjacent weedy areas, you can always catch a few small fish up shallow. When they make the transition from the weeds out to the rock bars, points, and humps mid summer, you can always catch a few smaller fish in the weeds. Late in the fall when all the big girls have gone deep, you can still catch smaller fish in the weeds.
That leads me to believe that the smaller fish just don't move around as much. Maybe that's because there's enough food to sustain them and they simply don't NEED to move. The big females need big meals. They have eggs to grow.
So when talking about transition, do we need to differentiate between the largest fish in the system and the smaller fish in the system? It would seem so from where I sit.
On a slightly unrelated note...
Where are the really small muskies? The yearlings, the 2 and 3 year classes? 32" seems to be the bottom end of where I've ever seen or caught them. Where the heck are they before that? |
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Location: Hayward, Wisconsin | EA: A couple of observations from my radio tracking work on Eagle Lake that addresses a couple of your statements/questions.
In Eagle, it was the larger males (over 25 pounds) and the females that did the most traveling and feeding in open/deep water where cisco's were present. The smaller males stayed in the shallow weeds all summer, but were very spooky.
As for the really small muskies, we caught none in the nets, which would be expected, since they are not yet ready to spawn, however, we were in shallow weeds. So where were they? I believe on Eagle they stay in deeper water until they are large enough to compete. Angling experience on Eagle: I kept track the first several years we went there and of our first 57 muskies, only ONE was under 38 inches (a 15-incher) and in those days we mostly fished shallow weeds. During my tracking year, communication with walleye anglers determined that in early August they began catching small muskies in 18-22 feet of water while fishing for walleyes.
Yes, still LOTS we don't know about these fish... |
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Location: Rhinelander, Wisconsin | Larry,
We were surprised to catch a 35 on Eagle in about 4' of water last week. That fish was relating to a downed tree. It was the only 'small' muskie we saw. |
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