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Sunday, October 29, 2006

Living planet in decline

The WWF has released a new report detailing the decline in living species since 1970. The news is that marine species have declined by more than 25%. The report highlights how the destruction of mangrove forests (by 1/3 between 1990 and 2006) is a major contributor to the decline of marine biodiversity, and, of course, commercial fishing. Speaking of which, even the US Government has now realised the insanity of current practice, go here for a new report, which shows how over-fishing affects fish populations. Here's a quote from that report:

"We found that the variability of the targeted populations was much higher, meaning that fishing tends to amplify both the peaks and the valleys of population numbers," said George Sugihara, a co-author of the paper and an oceanographer at Scripps. "Fishing can potentially not only lead to declining stock levels, but cause populations to fluctuate more through time, which could put them at greater risk of collapse than previously thought."

The scientists believe that the reason fished populations become more variable is because fishing selectively culls the larger, older individuals, thereby removing the fish that are more able to buffer random environmental variation. These individuals also tend to be the most reproductively active.

As fishing proceeds, there is a tendency for the size and age of individuals in the population to decline, potentially leaving a stock of near-juveniles that are less able to cope with environmental events such as El Niño.

And, here's a graph from the WWF report showing the decline of species:

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Speaking of reports, there's also a new one out on the cost of climate change. If the suffering of humans and untold other creatures doesn't move you, then the 7 trillion dollar price tag might.

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