What do you do when you spot an endangered animal eating another endangered animal? It sounds like a bad joke, but earlier this year, conservations found themselves on the horns of this very real dilemma, when California sea lions began seriously depleting chinook and steelhead salmon stocks in the Columbia River. We covered this report in the spring, where the compromise then granted officers of the Columbia River Inter-Tribal Fish Commission a license to kill, with caveats.
Since previous attempts to dissuade or scare away the ravenous marine mammals had failed. Officers could shoot those sea lions who were found continually returning to feast on the hapless fish. Salmon, of course, return upstream to freshwater to spawn, though they live in the ocean the rest of their lives. From a strategic point of view, they’re very vulnerable to predators, both due to their large numbers, and the constrained space as they tirelessly climb upriver, leaping over brooks and waterfalls along the way.
Since our last article on the subject, an uproar from animal welfare groups, led by the Humane Society, resulted in a lawsuit, still pending, intended to remove the legal permissions for the sea lion culling. Meanwhile, the problem has gotten worse, as Nature reports.
Over 40 of the sea lions, normally protected, were killed under this special exemption. Rather than minimizing the over-predation on the salmon, however, it has opened up room for a different species, the stellar sea lion, to take advantage of the free lunch. Stellar sea lions consume as much as five times the salmon compared to an individual of the protected species.
Indeed, sea lions are very intelligent animals, and once this “secret fishing spot” was discovered, word was certain to spread. But maybe this wouldn’t be an issue if efforts to recover sea lion populations hadn’t been so successful. The California sea lion’s numbers have tripled since it was given protected status. So do we unleash even more violence on both sea lion species, or do we leave the salmon to their fate (which was extinction in a similar case a few years ago)?
Or maybe it sounds like I’m implying we never should have saved the sea lions in the first place. Not at all, I assure you. It’s just worth noting that nature tends to find the easiest path to equilibrium. There was a certain balance amongst species on this continent before people came here in large numbers, in the first wave 10,000 years ago, and then again just over 500 years ago.
Despite our best intentions, even simply backing off won’t necessarily lead to the same species populations and relationships as existed before we got here. Sometimes balance (where balance is defined as a steady state in terms of which species exist and their population sizes) is restored simply by one or more species disappearing, with others taking over their niches.
On an individual level, animals don’t care about biodiversity or species preservation. That’s an emergent property that occurs spontaneously after a significant period of time. Having knocked over several dominoes already, we’ll probably find it’s not at all easy to put things back the way they’re “supposed” to be. In a system this complicated, nearly every move we make is likely to have some unintended consequences.
Photo credit: Oregon Department of Fish and Wildlife