Monday, April 5, 2010

Meddling With the Predator vs. Prey Relationship: man must pay up in sometimes surprising ways

When we selectively eliminate critical species from ecosystems, there is a price to be paid not only by the animal itself and the ecology. Man too must pony up - but our price may not be so obvious. It may be a price that is paid years down the road or is one we choose to ignore in the face of immediate personal or commercial gain.

This is what was once faced by cattlemen with regard to the hunting of wolves in the northern United States. Whatever was gained by cattle ranchers in eliminating a key predator, it ultimately came back to haunt them when the deer and varmint population exploded and competition between nature and the cattlemen for suitable grazing land necessitated bringing back the wolf population. But now the pendulum seems to be swinging back and the hunt for wolves is once again beginning in earnest - with no lessons apparently learned.

Many commercial fisheries stand on the brink of collapse, but sometimes the reason is not the obvious one: overfishing of a particular species. In some cases, it is rather the domino-like effect of our actions - as in the case of the hake fishery in Chile which has been severely impacted by the expansion of the Humboldt squid population, a voracious predator whose numbers have grown because of the commercial elimination of the squid's primary natural predators: sharks, tuna, and billfish.

This secondary effect is now being seen in other regions along the eastern Pacific coast: in the Sea of Cortez, where catches of grouper are in decline; and Northern California, where local fishermen are switching from catching rockfish to hauling up huge quantities of squid.

Here's a short video from my recent assignment in the Sea of Cortez.

The filming was for an important future program about which I have to be tight lipped for the time being. But the issue regarding Humboldt squid, which represents one of the multiple effects of disrupting once-balanced marine ecosystems, is an ongoing and growing one.

You fish. The fish are all gone. You move on. It's not that simple anymore.

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