Unnatural selection: Fish growing up fast

[FLPanhandle]

http://www.newscientist.com/article/dn20420-unnatural-selection-fish-growing-up-fast.html

If we humans are good at hunting, we excel at fishing. As we vacuum up stupendous numbers of fish from oceans, rivers and lakes, the nature of the ones that get away is changing at an astonishing rate.

In particular, the targeting of big animals drives the evolution of smaller fish or ones that become sexually mature at a younger age, or both. Many fish populations are changing dramatically, with average size shrinking by 20 per cent and average life histories 25 per cent shorter (Proceedings of the National Academy of Sciences, vol 106, p 952). Harvested species show the most abrupt trait changes ever observed in wild populations, Michael Kinnison of the University of Maine and colleagues reported recently.

Such changes have been documented in many places, including: pilchard off West Africa; American plaice off Newfoundland; Atlantic salmon in Canada and the UK; herring and grayling off Norway; chum salmon in Japan; sole, haddock and European plaice in the North Sea; whitefish in Alberta; sockeye salmon in Alaska; chum salmon, coho salmon and pink salmon in British Columbia; shellfish in California and cod just about everywhere. What's more, this long list includes only the cases where rigorous studies have been done. It's likely such changes are occurring in every population where large fish are targeted.



Another example of how much of an impact human population is having on the oceans. Many studies predict that commercial species will be completely fished out in the next 50 years. Too many mouths to feed.

[shraby]

1. I read about that several years ago that the taking of the

large fish is reducing the size of what is left.

[FLPanhandle]

4. Pays to be smaller than the openings in the nets

Not surprised by this either. Strong selection factor we've applied to these species.

[elleng]

2. No surprise, perfectly logical. Another one of nature's ways to demonstrate who's boss.

[jpak]

3. and more evidence for teh dreaded evolution

yup

[CBGLuthier]

5. What exactly is unnatural about it?

Haman beings are themselves a part of nature.

[FLPanhandle]

8. Humans are

However, fishing boats with long lines & nets aren't natural. Fishing nets didn't evolve. They are "unnatural" items that humans use, thus the terminology

[CBGLuthier]

13. They are tools we create. Beavers build dams. Other animals do use tools.

Absolutely nothing unnatural.

[formercia]

6. Not always.

Some jurisdictions have regulations regarding the size of fish that can be taken, where fish, over and under the 'slot' keeper size must be released unharmed. Striped Bass are a good example. Fish stocks in the Northeast are increasing due to better management and boats are being allowed to take more fish or spend more days at sea as a result.
Where collapse of species have occurred, it had been largely due to poor regulation and greed. The Mediterranean Tuna stocks are a good example.

[msongs]

7. humans will outbreed their food supply, and fish will get repopulate nt

[FLPanhandle]

10. Eventually.

In the meantime, it'll get very messy for the animals of the earth with 7 billion starving humans looking for something to eat.

[Keith Bee]

9. I blame Britney Spears

Just kidding. K&R

[FLPanhandle]

11. If you had said Justin Bieber, I'd have agreed with you

Speaking as a dad with a 12 year old daughter. :)

[veganlush]

12. Boycott cruety

Go Vegan!