Mature Fish Are Found In Deeper Water Because of Humans (arstechnica.com) 77
An anonymous reader quotes a report from Ars Technica: When studying populations of a flounder-like North Sea fish called plaice in the early 1900's, a man named Heincke noticed that older, larger fish are found deeper in the water than younger, smaller fish. The same phenomenon was subsequently found for other North Atlantic species like cod, haddock, pollock, and some species of flatfish; it was thus dubbed Heincke's Law and treated as an established fact. Biologists assumed it was ontogenic in nature, meaning that it must be connected to how the fish age and mature.
All the species in which older, bigger fish are found in deeper water have something else in common: we eat them. Could it be, some Canadian scientists wondered, that all the big fish are found in deeper water because we fished them out of shallower water? Apparently (and somewhat astonishingly) this possibility had never been evaluated. And the scientists found that not only could this be the case -- it in fact was. "[T]he researchers added a simulation in which the depth and mass of fish were tied to the rate of mortality by fishing," the report adds. "When set to mimic the actual fishing rate over the two decades spanning the dataset, the model outcomes were consistent with both the new and old fish data. When fishing mortality rates were increased in the model, larger fish moved progressively deeper. And when fishing rates were set to zero in the model, there was no age-related deepening seen at all." The study has been published in the PNAS journal.
All the species in which older, bigger fish are found in deeper water have something else in common: we eat them. Could it be, some Canadian scientists wondered, that all the big fish are found in deeper water because we fished them out of shallower water? Apparently (and somewhat astonishingly) this possibility had never been evaluated. And the scientists found that not only could this be the case -- it in fact was. "[T]he researchers added a simulation in which the depth and mass of fish were tied to the rate of mortality by fishing," the report adds. "When set to mimic the actual fishing rate over the two decades spanning the dataset, the model outcomes were consistent with both the new and old fish data. When fishing mortality rates were increased in the model, larger fish moved progressively deeper. And when fishing rates were set to zero in the model, there was no age-related deepening seen at all." The study has been published in the PNAS journal.
Never been evaluated (Score:3)
Gee, I wonder why no one ever "researched" this. Maybe they can study why wolves aren't commonly found around major cities next.
Re: Never been evaluated (Score:2)
There are no old, bold pilots
Fish Evade Predators... (Score:4, Insightful)
...news at eleven.
Seriously, how is this a surprise to anyone?
Re: (Score:2)
Re: (Score:2)
It didn't surprise me at all because—brace yourselves, now—I've actually spent time around lakes where people go fishing (and amongst whom this amazing discovery counts as "common knowledge").
Re: (Score:2)
...news at eleven.
Seriously, how is this a surprise to anyone?
Or, there are more of them left where there are less predators.
Re: (Score:2)
...news at eleven.
Seriously, how is this a surprise to anyone?
There are myriad things that, once someone notes it, are "obvious". In retrospect. It takes some work to be the first.
The one-click purchase patent is a good example. Many found it obvious...after the fact. Before then, programmers had a dozen confirmations before a purchase.
Re: (Score:2, Funny)
Re: (Score:1)
Um, they have. Babelfish.
Re: (Score:3)
One should take the time to validate seemingly self-evident things. otherwise, you end up telling many generations that the sun goes around the earth.
Obviously, everyone doing it or doing it all the time is a waste. So, there's a balance there.
Re: (Score:2)
"Apparently (and somewhat astonishingly) this possibility had never been evaluated." Gee, I wonder why no one ever "researched" this. Maybe they can study why wolves aren't commonly found around major cities next.
Actually wolves and foxes are pretty commonly found inside and around cities in many parts of the world. The reason is that there is plenty of food there in the form of rubbish (and pets), that in the densely settled areas people usually mistake them for dogs and the ones that don't mistake them for dogs are normally arrested the instant they start shooting at these animals inside of town or city limits because it is illegal and endangers the lives of other humans so cities are a surprisingly safe place for
Re: (Score:2)
*Yawn*
Evolutionary pressure (Score:5, Insightful)
"When set to mimic the actual fishing rate over the two decades spanning the dataset, the model outcomes were consistent with both the new and old fish data. When fishing mortality rates were increased in the model, larger fish moved progressively deeper.
I think this falls under confirming the obvious. Our fishing creates an evolutionary pressure. Fish that survive our hunting will tend to be the ones that prefer places where our nets don't reach as often. As long as we don't hunt them to the point where the population collapses it's perfectly obvious that we would see them evolve in response to our fishing tactics over time.
Re:Evolutionary pressure (Score:5, Interesting)
"When set to mimic the actual fishing rate over the two decades spanning the dataset, the model outcomes were consistent with both the new and old fish data. When fishing mortality rates were increased in the model, larger fish moved progressively deeper.
I think this falls under confirming the obvious. Our fishing creates an evolutionary pressure. Fish that survive our hunting will tend to be the ones that prefer places where our nets don't reach as often. As long as we don't hunt them to the point where the population collapses it's perfectly obvious that we would see them evolve in response to our fishing tactics over time.
If this were primarily evolutionary driven, we would find more smaller ones in deep water too as the surviving big fish pass on the behavioral genes to go deep to their young.
I think this could be behavioral. Small fish need smaller foods than big fish. Smaller foods are nearer the surface because that's where the primary conversion of sunlight to growth is with micro-flora and the micro-fauna that feed on them.
This might be more complex than the knee-jerk "it must be humans" response. Of course, it could turn out to be that we just eat the big fish in the upper-levels, but it's not OBVIOUS until we test it and find out that this is true.
This isn't evolution. (Score:1)
Evolution takes place over thousands of generations.
Heck... it's hardly migration. "Deepening" differences are measured in ranges from 60 to 120 meters deep.
It's simply the fact that fish live longer lives if they don't get caught. And they don't get caught cause nets don't reach that deep.
In fact, study explicitly states that it's most probably not evolution - but a part of a normal development instead.
Observations of depth distributions of older cod during a moratorium on fishing supported this prediction; however, younger cod exhibited low-amplitude deepening (10-15 m) suggestive of an ontogenetic response.
I.e. Young and inexperienced fish don't know how to hide from the nets OR the easy picking food (bottom d
Clueless about evolution (Score:4, Informative)
Evolution takes place over thousands of generations.
No it does not require thousands of generations. Have you ever seen a purebred dog? Humans applied selective breeding and can develop a completely new breed of dog with just a few generations. Evolution CAN happen slowly but it does not have to. It can happen quite quickly given the proper evolutionary pressures.
Heck... it's hardly migration. "Deepening" differences are measured in ranges from 60 to 120 meters deep.
Evolutionary pressure don't not care about what you perceive to be a small difference in distance. All that matters is whether that difference in depth creates an advantage in reproduction. If the difference in depth causes a difference in reproductive rates within a population then voila, you have an evolutionary pressure.
I.e. Young and inexperienced fish don't know how to hide from the nets OR the easy picking food (bottom dwelling crabs and crustaceans) they're munching on isn't available that deep.
The ones that prefer the locations where they do not get hunted (the reasons why don't matter) are the ones that will be selected to breed again. Small fish that don't prefer the deep get removed from the gene pool before they reproduce and so they never become big fish. Do this enough times and you will have selected for fish that prefer deeper waters. That my friend is an evolutionary pressure at work and it happens all the time.
Re: (Score:2)
Have you ever seen a purebred dog? Humans applied selective breeding and can develop a completely new breed of dog with just a few generations. Evolution CAN happen slowly but it does not have to. It can happen quite quickly given the proper evolutionary pressures.
You don't seem to understand the difference between selection for traits and evolution.
Hint: Look up dog. [wikipedia.org] Now scroll down to "species". [wikipedia.org]
In the parlance of the times - when you see it, you'll shit bricks.
E.g. How do you think they created a labradoodle? You're thinking of breeds, buy you think that you're thinking of species.
You know... as in the title of the book. [wikipedia.org] Which is not "On the Origin of Breeds".
Same goes for your ideas about "evolutionary pressure".
The ones that prefer the locations where they do not get hunted (the reasons why don't matter) are the ones that will be selected to breed again. Small fish that don't prefer the deep get removed from the gene pool before they reproduce and so they never become big fish. Do this enough times and you will have selected for fish that prefer deeper waters. That my friend is an evolutionary pressure at work and it happens all the time.
You should lay off of those ideas that sound like yo
Re: (Score:2)
[Citation needed]
Re: (Score:2)
Not true at all. There was a Russian geneticist who turned violent foxes into cute puppies in less than a dozen generations.
Re: (Score:2)
That's not evolution. That's selection for traits.
Hint: If they can still breed with the "original" - it's not evolution.
Evolution is a branching - not a straight line.
That's why humans can't breed with other primates, nor can those other primates breed with each other.
Re: (Score:2)
Evolution is the process, not the distance. Not being able to breed makes it a different species, but "the process by which different kinds of living organisms are thought to have developed and diversified from earlier forms during the history of the earth" (or "the gradual development of something, especially from a simple to a more complex form") covers the intermediate generations too.
Re: (Score:2)
Evolution is the process, not the distance. Not being able to breed makes it a different species, but "the process by which different kinds of living organisms are thought to have developed and diversified from earlier forms during the history of the earth" (or "the gradual development of something, especially from a simple to a more complex form") covers the intermediate generations too.
It's not EXACT nor finite distance.
For the "process" to be taking place, there has to be genetic change. Not just expression of different genes, already present.
Distance has to be covered, but just covering the distance is not what it is all about.
Nor is the "quality" of covering those distances related to speed (i.e. time) one spends during the process or at any particular location in it.
A better analogy would be journey vs. distance. Going from 1 to 47 (and beyond) one passes locations of 12, 15, 25, 37 a
Re: (Score:3)
See also:
1. Dendelions growing up, flowering, and seeding in less than a week to squeeze between weekly mowings.
2. Trump voting masses appearing smaller than they are because of fears of talking about it in social media or even polite company.
Re: (Score:2)
See also:
2. Trump voting masses appearing smaller than they are because of fears of talking about it in social media or even impolite company.
FTFY
No one is bothered talking about or in support of Trump around conservatives or moderates. It is when the leftists enter that we can expect name calling, screaming, protests and other ridiculous and impolite behaviors. You might want to consider why you never are around for the reasonable conversations.
Re: (Score:2)
For any generation of fish, some prefer different depths of water. The ones that get scooped out of the water by nets don't get to breed. The ones that survive, get to breed. That shifts the average preferred depth. And the process repeats.
Re: (Score:2)
That fish are able to make and consistently act on a plan of survival sure is. I always assumed fish were stupid, but here they are.
Individual fish aren't necessarily using intelligence and acting on a plan. They could be inanimate objects and the results would be the same. The ones in the shallow waters are more likely to get caught. This could be personal preference of individual fish, some genetic difference in buoyancy, temperature preference, etc.. Why they are at a different depth doesn't really matter. What matters is the ones that are at the deeper depths are less likely to be caught and therefore more likely to grow bigg
be careful with computer models (Score:5, Informative)
Re: (Score:2)
Thanks for this, it is a well balanced statement of the situation.
It is amusing, and predictable on /., to see when a natural science story posted how the commentors here split between "that's a stupid study because it is so obvious" and "that isn't true because I just thought up another reason without reading the TFA".
Lots of people here don't get the whole "science" thing.
Even in the fishtank (Score:5, Interesting)
Even in a controlled environment like a fish tank, in lots of species, the younger fish hang out at the top of the water more than older fish. (now the reverse can be true in some species if the fry hide at the bottom instead- but most fry go to shallow or higher waters). No one is fishing fish out of my fishtanks.
In the ocean (or a pond, or a fishtank) small microscopic lifeforms are found in higher densities at the surface- because that is where the sunlight is. Whatever eats those lifeforms needs to be nearby... whatever eats those needs to be near them.
The larger you get, the more varied food you can eat- you don't necessarily have to stick with micro-fauna and micro-flora at the surface.
It may be that we eat the fish at the surface- and that's why no big ones there... or it could be because large fish simply don't NEED to be near the surface like small ones do.
Re: (Score:2)
BTW, thank you for providing an alternative explanation to the various "this is obvious, why evaluate this" crowd. Of course, the point of the study was to isolate the effect of fishing, which they found to be significant.
Re: (Score:2)
Small sharks eat fish. But larger and older sharks need to eat seals to satisfy their energy demands.
Missed opportunity. (Score:5, Funny)
Mature Fish Like It Deep, Really Deep
This could have been your headline Slashdot but you blew it. ;)
Re: (Score:2)
To the perverted everything has to be perverted.
Headline: "Pervert Proves His Own Point"
Re: (Score:3)
Mature Fish Like It Deep, Really Deep
This could have been your headline Slashdot but you blew it. ;)
Do YOU like Fishsticks?
Re: (Score:2)
Oh geez, I'm going to hell for this, but would you say it makes them wet?
Re: (Score:2)
Yes. But, it still smells like fish.
Re: (Score:2)
Just think of the ensuing "that's what she said" retorts.
Wait a Minute (Score:2)
Older fish are bigger and heavier too, so they should sink more. /sarcasm
Really? (Score:2)
So...model built to simulate preconceptions of researchers somehow coincidentally validates those preconceptions?
That's idiotic.
At least in lake environments, younger fish stay in shallower water for several pretty obvious reasons:
- there's more aquatic plant life, providing them cover
- the shallowest water
- they have little or nothing to fear from predator birds (Well, filter-feeders now have evolved to defeat that....)
I'd submit the logic of the open ocean isn't terribly different - surface churn likely
Re: (Score:2)
Yeh, thanks. Lets stop all science because Styopa has some anecdotes instead.
Re: (Score:2)
No, model built to see if pressure ields observed effect duplicates observed effect.
This pretty bad.
Natural selection at work (Score:2)
Fish that swim in deeper waters survive, and pass their genes on. Fish that swim in shallower waters get eaten.
Rather obvious conclusion (Score:2)
So, where it's easier to go fishing (closer to the coast, in shallower water, nicer weather) you saying fish tend to get fished more and hence not as big of fish. Hmmm, did we need to say this out loud to believe it or couldn't people just connect the dots and figure this out themselves? I like going crabing, and you know what, if I go deeper I tend to get bigger crabs since not all people have the ability to crab there. Shocking.
Does not actually prove anything (Score:2)
I can think of two possible explanations for the observed data. The study does not actually test between them.
Explanation 1: When people fish in a
more than fish (Score:2)
For many decades now it's been illegal to shoot deer that are within a couple hundred feet of a home. How soon are they going to noticeably prefer suburbia over wooded areas? I know that my hometown in New Jersey had no deer 50 years ago, but it's almost overrun with them now.
I honestly had no idea that we.... (Score:2)
"in the early 1900's" (Score:2)
Re: (Score:2)
Speaking of fish... in a barrel... BANG! [wikipedia.org]
Re: (Score:2)
Speaking of fish... in a barrel... BANG! [wikipedia.org]
I'm sure you had a point here, maybe read the question next time....