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.