A Different (But Still Undesirable) Kind of Downsizing

Posted: 2009-04-14 in General
Tags: , , , , , , ,

I've always had a fascination for news and studies regarding the theories of evolution and natural selection.  Heck, I even intentionally went out and bought a copy of Darwin's Voyage of the Beagle because I was interested in reading of the accounts that led up to Darwin's initial publication of his theory.  So when I read Very Short List's summary of the Royal Society's article on the "Reversal of Evolutionary Downsizing Caused by Selective Harvest of Large Fish", I was hooked immediately (no pun intended).

Although I don't have the funds to sign up to read the whole article, the summary VSL provides is quite interesting:

Fifteen years ago, scientists discovered that heavy fishing can create “fishing-induced evolution” — the more big fish we pluck out of the sea, the smaller the adult size of each successive generation. But according to a new study led by SUNY Stonybrook fishery biologist David Conover, the process is reversible.

Conover worked with ten generations of captive silversides. For the first five generations, he removed the biggest fish to simulate overfishing; as expected, this removal of “big-fish” genes reduced the average size of the adults in each subsequent generation. For the next five generations, Conover removed fish randomly to see whether the adults would start to rebound to their former size. They did, but nature made up for just half of the size reduction that Conover’s simulated overfishing had caused.  Conover does expect the fish to return to full size but estimates that it’ll take another five generations — in other words, the recovery takes twice as long as the injury.

Although this pattern of behavior is probably not limited to fish or even animals in general, it does bring up the issue that the recovery from injury can ONLY occur once the outside influence is removed from the environment, and only if it is removed before irreparable damage is caused.  I'm worried that for some of our ecosystems, we won't realize we've reached the point of no return until after it's too late. 

As seen with the devastating loss of cod stock in Newfoundland in the 1990s, the impacts are more than just environmental: the eradication of a species or ecosystem can mean the loss of jobs for thousands of individuals.  And just like the species our collective actions damn to extinction, these jobs may never return, either.  It's up to all of us to do our part – at a minimum, please get (or stay) informed and make smart choices as consumers to help influence how others treat the world around us.  It may sound trite, but future generations WILL thank you for your efforts.

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