The conservationist accepts death and suffering as a natural product of the competition for resources. But faith in free-market biology doesn't always lead to laissez faire environmental policies. In order to preserve biodiversity, the conservationist might intervene to promote the welfare of one species over another, on the grounds that not all animals are created equal. The EDGE of Existence program of the Zoological Society of London combines two scores—extinction risk and evolutionary distinctness—to prioritize species that will maximize the genetic diversity of life on Earth. Screw the Beluga whale (No. 272); we need to save the Cuban solenodon (No. 2)!
While humans may find much to appreciate in Earth's menagerie, it is hard to argue that preserving DNA can justify the murder of a sentient being. Sea lions are remarkable creatures. Some believe their cognitive abilities rival those of chimpanzees: In 1993, a female sea lion at the University of Santa Cruz named Rio became famous for being the first nonhuman animal to understand the transitive property—if A equals B, and B equals C, then C equals A. Single females are known to baby-sit young pups while their mothers go fishing. And with social animals, the murder of one may well traumatize the entire group, as has been documented in elephants. Salmon, on the other hand, have a brain that looks like a knotted shoelace, and some scientists argue that the absence of a neocortex means the fish lack a psychological experience of pain.
We may have a sense of what it means to kill an innocent sea lion, but it's hard to anticipate the moral consequences of an ecosystem's downward spiral. If we take a consequentialist view of ethics, we cannot distinguish between an action and a lack of action. If the only way to stop a mass murderer were to kill him, and I refused because of my belief that it is wrong to kill, then I would no doubt be responsible for the murderer's future victims. Even if this murderer were severely intellectually disabled—the cognitive equivalent of a pinniped—I would still be compelled to kill him.
Taking this tack, ecologists may argue that it's worth killing sea lions to save the salmon. Salmon eat smaller fish in marine estuaries and carry key nutrients up river systems, where the salmon themselves become food for other fish, birds, and mammals. According to one study, more than 40 species of mammals and birds in Alaska feed—at least some of the time—on salmon and their eggs. Bears and eagles fertilize evergreens with the salmon carcasses they dump onshore. If salmon vanished tomorrow, some animals would find other places to live and other things to eat, but the net effect might be an increase in the number of deaths due to starvation—and a curtailment of whatever pleasure human and nonhuman animals derive from the presence of salmon.
The tricky part is figuring out what those effects would be. A sound conservation ethic cannot be based exclusively on a vague principle of biodiversity or the sanctity of the natural world. Instead, it must respect the interests of sentient beings. We have to ask ourselves if saving salmon will lead to the greatest good for the greatest number, or if the pain inflicted by trapping and killing sea lions year after year will overwhelm whatever greater good is done for our planet.
The truth is that thorny ethical questions like this one can sometimes be avoided altogether. In the dispute over the Columbia River, conservationists and animal rights advocates alike believe that the real problem at Bonneville Dam is the existence of Bonneville Dam. Without that man-made structure, the salmon would not face the bottlenecks that prevent many from getting to their spawning grounds, and sea lions would not find themselves perishing inside a metal trap. So, the one thing we can all agree on is our own misanthropy: We shouldn't be holding animals accountable for the damage humans have wrought.