Monday, November 06, 2006

Sorry Charlie -- You're Dead

Complexity in the Field
By J.B. Ruhl

Perhaps I'm dating myself, but I remember the "Sorry, Charlie" TV ads for the Star Kist brand of tuna that showed a tuna named Charlie (yes, he wore a hat and glasses) saddend because Star Kist refused to catch him--he just wasn't up to their standards.

Well, Charlie probably would have no problem getting hooked these days. According to a report out in Science this week, we're catching fish (and destroying marine habitat) at an unprecendented pace, so much so that the researchers predict "the global collapse of all taxa currently fished by the mid–21st century." That can't be good for Charlie and his pals.

The research, led by Boris Worm of the Department of Biology at Dalhousie University in Nova Scotia, analyzed local experiments, long-term regional time series, and global fisheries data to test how biodiversity loss affects marine ecosystem services across temporal and spatial scales. They found that, overall, rates of resource collapse increased and recovery potential, stability, and water quality decreased exponentially with declining diversity. Restoration of biodiversity, in contrast, increased productivity fourfold and decreased variability significantly. The research team concluded that marine biodiversity loss is increasingly impairing the ocean's capacity to provide food, maintain water quality, and recover from perturbations. They also believe, however, that conditions have not crossed the threshold of irreversibility, and they call for measures to restore marine biodiversity through sustainable fisheries management, pollution control, maintenance of essential habitats, and the creation of marine reserves.

I have to agree with the researchers that "business as usual would foreshadow serious threats to global food security, coastal water quality, and ecosystem stability, affecting current and future generations." Domestic and global marine policy is nothing short of entirely screwed up. But is the complete collapse of hundreds of marine taxa really possible within 45 years? Well, I'd be happy to have someone convince me it is not.

I am sure the report, which was picked up by media around the globe, will attract many smug assertions that the conclusion is absurd, that there is no way we will see the extinction of the world's marine species by 2050, or ever. To be sure, linear extrapolations from trend data are unreliable, particularly in the world of ecology, but if anything my guess is that it is more likely that any nonlinearity in the dynamic between "business as usual" and marine life will cut against sustainability.

So chalk this up as another high-stakes Type I Error/Type II Error bet we'll have to make on the scale of global climate change and in the context of a highly complex system. Do we invest in the measures the researchers recommend on the belief they may be right, in which case if they are wrong we spent a lot of money and left a lot of fish in the sea we could have eaten. Or do we continue with business as usual on the belief that they are wrong, in which case if they are right...well, if they are right, it's not just Charlie who's going to be feeling a lot of pain.

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