November 12, 2007 | David F. Coppedge

Gone Fishing: Can Humans Counteract Evolution?

Darwinists insist that human beings are part and parcel of the evolutionary process, but once in awhile, they criticize their fellow hominids for getting in Darwin’s way.  A recent example in Nature1 took aim at fishermen:

People like to catch big fish, sometimes so much so that fish sizes overall become greatly diminished.  According to one view, the continual removal of large fish from a population sets the stage for rapid, undesirable evolutionary changes, including slower growth, earlier adult maturation and permanently smaller size.  This occurs because removing the largest fish directly opposes natural selection, which tends to favour large size.

David Conover called this situation a “dynamic tug-of-war between the forces of natural selection and fishing selection.”  But as if anticipating a logical objection that fishing selection is subsumed under natural selection if humans are natural, he quickly tried to explain why fishing selection was against nature:

Why is evolution important to fisheries management?  It could be argued that fishing merely adds an additional predator to the ecosystem.  But from the fish’s point of view, humans turn the rules of engagement completely upside down.  Most natural predators attack smaller fish more frequently than larger fish.  The bigger a fish gets, the lower its mortality (Fig. 1).2  Hence, growing fast early in life is a good strategy.  Moreover, because big fish produce many more offspring than small fish, delaying maturation to larger size also increases fitness – that is, the likelihood that one’s genes will be passed on to future generations.  By causing greatly increased mortality at large sizes, fishing selects for fish that grow slowly and mature at small sizes.  Numerous other physiological, behavioural and reproductive traits likewise evolve that can lower fitness.  Taken to its extreme, many generations of intense size-selective fishing could in theory cause the evolution of a population of runts.

Humans, in other words, are causing unnatural change in fish populations.  This is evident in Conover’s choice of title, “Nets vs nature.”  But are humans causing the change on purpose?  Do they have the capacity to choose to do otherwise?  If so, does this reflect a decision that should be made on moral grounds?  These questions were not addressed.
    Citing work on population genetic responses to “fishing selection” for size, Conover argued that “evolutionary responses to the opposing forces of fishing and natural selection must be accounted for in managing fisheries.”  To him, this was an illustration that evolutionary theory is not just of academic interest, but has practical applications of interest to all of us.3

1.  David O. Conover, “Fisheries: Nets versus nature,” Nature 450, 179-180 (8 November 2007) | doi:10.1038/450179a.
2.  The figure is labeled, “The darwinian struggle between natural selection and fishing selection.”
3.  Conover also tried to pre-empt a charge of storytelling.  Correlation does not prove causation, he noted.  Also, “The responses are probably far too rapid to be entirely evolutionary as opposed to ecological in origin,” or merely coincidental, he confessed.  “With only one population under study, any interpretation of this sequence of growth changes contains an element of story-telling.
    His comeback was that “this is one of the most data-rich and comprehensive analyses of fishery-induced evolution ever published,” and agreement with other studies, he felt, shows the possibility that “all such studies are erroneous is becoming vanishingly small.”  Yet without an external criterion of how many cases are required to establish causation, and for how long a period, any such probability calculations seem subjective.

He said that “It could be argued that fishing merely adds an additional predator to the ecosystem,” so here we come, a predator to prey on evolutionary theory itself.  If he is going to be a consistent evolutionist, Conover cannot make a case that what humans are doing to fish populations is bad or even unwise.  You just watched him empathize with the poor little fishies: “from the fish’s point of view, humans turn the rules of engagement completely upside down.”  Who is he to become a crusader for fish’s rights?  That’s not fair, prosecuting attorney Conover whimpers before us members of the jury, pointing to the defendant, Joe Fisherman.  He didn’t play by the rules.  He flagrantly violated the Law of Natural Selection.  He is a big, fat cheater.  He should feel guilty.  He should be prosecuted to the full extent of the law, right here in Darwin’s Court.
    The defense attorney points out to the prosecutor that the Law of Natural Selection is that everybody plays, and anything goes.  The judge sits there dispassionately, not paying any attention.  In a world where anything goes, nobody’s guilty.
    Evolutionists routinely describe any situation, no matter how perverse or unfair to one side, as Darwinism in action.  Was it unfair for Cambrian predators to emerge and feed on soft-bodied organisms?  No; the prey just invented hard shells.  Was it unfair for a meteor to wipe out 90% of Permian life?  No, the survivors actually flourished in the newly-cleared playing field.  Was it unfair for hominids to grow bigger brains and think of new ways to terrorize their fellow creatures?  No, that is what led to philosophy, civilization and Darwinian theory.  Darwinists frequently talk of evolutionary “arms races” in this dog-eat-dog, Calvinball world where selfishness rules, a Hobbesian war of all against all.
    Why is Conover worked up, therefore, about what happens to a few fish?  Don’t worry, they’ll evolve.  Is he worried that they won’t be able to evolve fast enough?  Don’t worry; evolution can run as fast or slow as a Darwinian wants.  But what if they go extinct?  It just means they weren’t fit.  But what if humans artificially lower their fitness?  Sorry, we don’t understand the word artificial.  Everything is natural selection in the big picture.  But what if future fish populations consist only of runts?  Runts are fine.  Some animals grow large, some grow small.  Some mature fast, some mature slow.  Some diversify rapidly, some not at all for hundreds of millions of years.  What’s the problem?
    Maybe Conover is concerned about runts because he likes seafood.  That’s the only explanation that makes any evolutionary sense, because it is sufficiently selfish and irrational.  But for him to feel that humans might be doing something wrong or unnatural by changing the rules – that’s his conscience talking.  Darwin had nothing to say about conscience.  Become a Christian; then we can talk about acting as good stewards to preserve the environment for the wonderful creatures God made.  After all, a certain group of fishermen once left their nets to follow Someone who promised them a nobler purpose – to become fishers of men.

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