6 ms·

My take away from this is that letting the small fish go under the premise that they are juveniles that will later grow to be bigger lets the adult midgets go,

by ryao 1y ago

My take away from this is that letting the small fish go under the premise that they are juveniles that will later grow to be bigger lets the adult midgets go, ruining the gene pool. I wonder if this finding will have any impact on conservation rules against taking small fish when fishing.

thaumasiotes 1y ago
> ruining the gene pool In what sense? Is being bigger Platonically better than being smaller?
- thatguy0900 1y ago
  It's better if you want to eat them lol
  - bluGill 1y ago
    Small fish generally taste better in my experience. Small of course implies younger, so we let the biger ones go as well as small ones - there is a too small to eat point.
    - deleted 1y ago
      [deleted]
- hungmung 1y ago
  > Is being bigger Platonically better than being smaller? Maybe, most animals evolve towards larger sizes. Except on smallish islands, where they tend to become smaller.
  - deleted 1y ago
    [deleted]
  - thaumasiotes 1y ago
    > Maybe, most animals evolve towards larger sizes. This is not even a little bit true.
  - masklinn 1y ago
    > Maybe, most animals evolve towards larger sizes. Animals tend towards whatever size lets them maximise survival. This is based on available niches and other selective pressures. > Except on smallish islands, where they tend to become smaller. Island syndrome leads to both gigantism and dwarfism.
    - fpoling 1y ago
      > Animals tend towards whatever size lets them maximise survival. Evolution is a filter that removes unfit, it does not select the best fit. So a lot of mutations that slightly decreases fitness for the environment stay as they do not make an organism too unfit. This results in a gen pool diversity in a population that helps to survive if the environment changes as previously somewhat harmful mutations can be essential for survival in the new situation.
- p1necone 1y ago
  Presumably the optimal size for survival when humans aren't applying pressure via fishing is bigger. Perhaps "ruining" is hyperbolic, but this is making the fish less fit for their environment.
  - kbutler 1y ago
    ...less fit for their environment excluding human fishing pressure.
  - tzs 1y ago
    It is making them less fit for their environment? I can see how it is making them less fit for the environment they used to be in before they were subject to large scale human fishing, but that's not their environment now.
  - mattmaroon 1y ago
    If that’s the case it should return if we stopped fishing.
    - heavyset_go 1y ago
      Not always the case. Any number of things can happen that could prevent that from happening, like extinction, as an extreme example.
    - thoroughburro 1y ago
      No. A certain gene expression can just be gone forever. Nothing guarantees the desired expression will evolve again.
      - mattmaroon 1y ago
        Sure it does, there is still variation in the sizing of them. If the previous size was the ideal one, and assuming that has otherwise not changed, the larger cod will be more fit and breed more.
    - kwk1 1y ago
- ruined 1y ago
  if you're interested in maintenance of the fishery, size reduction is a primary indicator of failure. so yes
- kulahan 1y ago
  In the sense that the gene pool is being unintentionally manipulated by humans, when the original goal was to try and leave it undisturbed to an extent.
- wiseowise 1y ago
  Yes. It is.
twelve40 1y ago
maybe, but how can you possibly tell - in bulk - if you are dealing with a midget or really a young fish that had no chance to spawn? (which is the point here)
ruined 1y ago
trawlers historically haven't really discriminated by size. development of decent selective trawling equipment, and introduction of a minimum size is fairly recent as a data point, a recent change in regulations regarding eastern Baltic cod had no statistical effect on reported catch https://link.springer.com/chapter/10.1007/978-3-030-03308-8_10 https://link.springer.com/chapter/10.1007/978-3-030-03308-8_... >Data quality for stock assessments has deteriorated, discarding of cod has not decreased despite a reduced minimum size and there are no indications of increased gear selectivity in the fishery
- kbutler 1y ago
  ...haven't /INTENTIONALLY/ discriminated by size... The article says smaller fish could more easily escape the nets. Though it doesn't cite studies documenting that, it does seem reasonable.
magicalhippo 1y ago
> My take away from this is that letting the small fish go under the premise that they are juveniles that will later grow to be bigger lets the adult midgets go, ruining the gene pool. I read about this being tested in large fish tanks using either cod or trout some 20+ years ago, where they removed fish either randomly, or let the small ones go. They came to the same conclusion: letting small fish go results in reduction of average size of mature fish after a few generations. The authors of the submitted paper references this[1] article, which points out the following: Despite a theoretically strong conceptual basis, evidence of genetic change unequivocally attributable to wild-capture fisheries has been elusive. Among the top five threats to biodiversity, evidence for genetic trait change is strongest for studies of pollution and weakest for studies of overexploitation (and habitat change). Determining whether phenotypic change in declining populations is the result of evolution, as opposed to other influences on growth, survival, and fitness, or gene flow from adjacent populations, has proven challenging. So this paper seems to provide evidence that the lab results holds up in the wild. [1]: https://www.pnas.org/doi/full/10.1073/pnas.2105319118 https://www.pnas.org/doi/full/10.1073/pnas.2105319118
fny 1y ago
Id think the small fish are let go more often because they aren't good eats. No one is trying to cheat the warden for a six incher.
- londons_explore 1y ago
  A good chunk of fish caught are ground up and fed to chickens/other fish. The grinder doesn't care what size the fish are.
xbmcuser 1y ago
Being small is an evolutionary advantage in this case so that is understandable outcome. On the other hand for maine lobsters they let large males and egg laying females go with the large life spans of lobsters would be hard to compare if they getting larger
gus_massa 1y ago
There is a curious case with small male salmons: From https://www.fishingwithrod.com/articles/fish_biology/whats_up_with_jack.html https://www.fishingwithrod.com/articles/fish_biology/whats_u... > Size obviously matters when it comes to mating for salmon. However, being a small male can also succeed when it comes to scoring a female. The so-called "jacks" that are found in chinook and coho salmon are male individuals that return to their natal streams a couple of years earlier than expected. > Although they are much smaller than a fully grown male, they are also sexually matured when they reach the spawning ground. What advantages do these smaller fish have? It is obvious that they will not win when confronted by a fully grown male. Behavioural biologists believe that these jacks are "sneaker males". Their duty is to simply stand by when larger males are fighting for territory, and sneak in while unnoticed to mate with the females that are also waiting for the fights to end. As you can see, being big does not always have all the advantages, sometimes being small can be very beneficial too. IIRC the female already laid the eggs, and the big males start to fight. During the fight the small one sneaks a fertilice them. "Waiting" and "Mate" are misleading.
- kulahan 1y ago
  It's kind of hilarious to me that the female watches the males fight to the point that she doesn't even watch her own eggs. I wonder how long these jacks have been around?
  - gus_massa 1y ago
    IANAB IIRC salmons lay the eggs is swallow holes in a quiet part of the river. She is problably thinking that those idiots are going to spill the eggs and they will be drafted by the water and die, so she has to try to keep the fight away.
BlackFly 1y ago
Here is a decade old study talking about that: https://www.science.org/doi/10.1126/science.aac4249 https://www.science.org/doi/10.1126/science.aac4249
tsfenwick 1y ago
As a former commercial fisherman this is something we talked about on how there should be a max size limit.

by ryao 1y ago

thaumasiotes 1y ago

> ruining the gene pool In what sense? Is being bigger Platonically better than being smaller?

thatguy0900 1y ago
It's better if you want to eat them lol
- bluGill 1y ago
  Small fish generally taste better in my experience. Small of course implies younger, so we let the biger ones go as well as small ones - there is a too small to eat point.
  - deleted 1y ago
    [deleted]
hungmung 1y ago
> Is being bigger Platonically better than being smaller? Maybe, most animals evolve towards larger sizes. Except on smallish islands, where they tend to become smaller.
- deleted 1y ago
  [deleted]
- thaumasiotes 1y ago
  > Maybe, most animals evolve towards larger sizes. This is not even a little bit true.
- masklinn 1y ago
  > Maybe, most animals evolve towards larger sizes. Animals tend towards whatever size lets them maximise survival. This is based on available niches and other selective pressures. > Except on smallish islands, where they tend to become smaller. Island syndrome leads to both gigantism and dwarfism.
  - fpoling 1y ago
    > Animals tend towards whatever size lets them maximise survival. Evolution is a filter that removes unfit, it does not select the best fit. So a lot of mutations that slightly decreases fitness for the environment stay as they do not make an organism too unfit. This results in a gen pool diversity in a population that helps to survive if the environment changes as previously somewhat harmful mutations can be essential for survival in the new situation.
p1necone 1y ago
Presumably the optimal size for survival when humans aren't applying pressure via fishing is bigger. Perhaps "ruining" is hyperbolic, but this is making the fish less fit for their environment.
- kbutler 1y ago
  ...less fit for their environment excluding human fishing pressure.
- tzs 1y ago
  It is making them less fit for their environment? I can see how it is making them less fit for the environment they used to be in before they were subject to large scale human fishing, but that's not their environment now.
- mattmaroon 1y ago
  If that’s the case it should return if we stopped fishing.
  - heavyset_go 1y ago
    Not always the case. Any number of things can happen that could prevent that from happening, like extinction, as an extreme example.
  - thoroughburro 1y ago
    No. A certain gene expression can just be gone forever. Nothing guarantees the desired expression will evolve again.
    - mattmaroon 1y ago
      Sure it does, there is still variation in the sizing of them. If the previous size was the ideal one, and assuming that has otherwise not changed, the larger cod will be more fit and breed more.
  - kwk1 1y ago
ruined 1y ago
if you're interested in maintenance of the fishery, size reduction is a primary indicator of failure. so yes
kulahan 1y ago
In the sense that the gene pool is being unintentionally manipulated by humans, when the original goal was to try and leave it undisturbed to an extent.
wiseowise 1y ago
Yes. It is.

twelve40 1y ago

maybe, but how can you possibly tell - in bulk - if you are dealing with a midget or really a young fish that had no chance to spawn? (which is the point here)

ruined 1y ago

trawlers historically haven't really discriminated by size. development of decent selective trawling equipment, and introduction of a minimum size is fairly recent as a data point, a recent change in regulations regarding eastern Baltic cod had no statistical effect on reported catch https://link.springer.com/chapter/10.1007/978-3-030-03308-8_10 https://link.springer.com/chapter/10.1007/978-3-030-03308-8_... >Data quality for stock assessments has deteriorated, discarding of cod has not decreased despite a reduced minimum size and there are no indications of increased gear selectivity in the fishery

kbutler 1y ago
...haven't /INTENTIONALLY/ discriminated by size... The article says smaller fish could more easily escape the nets. Though it doesn't cite studies documenting that, it does seem reasonable.

magicalhippo 1y ago

> My take away from this is that letting the small fish go under the premise that they are juveniles that will later grow to be bigger lets the adult midgets go, ruining the gene pool. I read about this being tested in large fish tanks using either cod or trout some 20+ years ago, where they removed fish either randomly, or let the small ones go. They came to the same conclusion: letting small fish go results in reduction of average size of mature fish after a few generations. The authors of the submitted paper references this[1] article, which points out the following: Despite a theoretically strong conceptual basis, evidence of genetic change unequivocally attributable to wild-capture fisheries has been elusive. Among the top five threats to biodiversity, evidence for genetic trait change is strongest for studies of pollution and weakest for studies of overexploitation (and habitat change). Determining whether phenotypic change in declining populations is the result of evolution, as opposed to other influences on growth, survival, and fitness, or gene flow from adjacent populations, has proven challenging. So this paper seems to provide evidence that the lab results holds up in the wild. [1]: https://www.pnas.org/doi/full/10.1073/pnas.2105319118 https://www.pnas.org/doi/full/10.1073/pnas.2105319118

fny 1y ago

Id think the small fish are let go more often because they aren't good eats. No one is trying to cheat the warden for a six incher.

londons_explore 1y ago
A good chunk of fish caught are ground up and fed to chickens/other fish. The grinder doesn't care what size the fish are.

xbmcuser 1y ago

Being small is an evolutionary advantage in this case so that is understandable outcome. On the other hand for maine lobsters they let large males and egg laying females go with the large life spans of lobsters would be hard to compare if they getting larger

gus_massa 1y ago

There is a curious case with small male salmons: From https://www.fishingwithrod.com/articles/fish_biology/whats_up_with_jack.html https://www.fishingwithrod.com/articles/fish_biology/whats_u... > Size obviously matters when it comes to mating for salmon. However, being a small male can also succeed when it comes to scoring a female. The so-called "jacks" that are found in chinook and coho salmon are male individuals that return to their natal streams a couple of years earlier than expected. > Although they are much smaller than a fully grown male, they are also sexually matured when they reach the spawning ground. What advantages do these smaller fish have? It is obvious that they will not win when confronted by a fully grown male. Behavioural biologists believe that these jacks are "sneaker males". Their duty is to simply stand by when larger males are fighting for territory, and sneak in while unnoticed to mate with the females that are also waiting for the fights to end. As you can see, being big does not always have all the advantages, sometimes being small can be very beneficial too. IIRC the female already laid the eggs, and the big males start to fight. During the fight the small one sneaks a fertilice them. "Waiting" and "Mate" are misleading.

kulahan 1y ago
It's kind of hilarious to me that the female watches the males fight to the point that she doesn't even watch her own eggs. I wonder how long these jacks have been around?
- gus_massa 1y ago
  IANAB IIRC salmons lay the eggs is swallow holes in a quiet part of the river. She is problably thinking that those idiots are going to spill the eggs and they will be drafted by the water and die, so she has to try to keep the fight away.

BlackFly 1y ago

Here is a decade old study talking about that: https://www.science.org/doi/10.1126/science.aac4249 https://www.science.org/doi/10.1126/science.aac4249

tsfenwick 1y ago

As a former commercial fisherman this is something we talked about on how there should be a max size limit.