http://www.straight.com/article-345025/vancouver/marine-mammals-return-strait-georgia“Certain marine mammals, like seals, sea lions, and some whale species, are very curious,” says Lisa Spaven, who heads up the B.C. Marine Mammal Response Network, based at the Pacific Biological Station in Nanaimo. “And like garbage bears, they’re looking for ways to find their prey more easily, which can lead to increased interaction with fishing gear. Certain marine mammals are known for depredating, which means taking fish off lines, and that then becomes an issue—not only for the marine mammals in that they’re getting entangled, potentially, but also for the fishermen, because they’re having damage to or losing their gear, or losing their catch.”
When a happy pinniped swims off with the salmon a recreational angler was planning on having for dinner, it’s understandable that the aggrieved party might want to call for a renewal of the seal cull. Pressure is mounting on the government for just such an action, but that, Trites says, would be a mistake.
“One of the controversies that I see coming up over and over is, ‘There’s too many harbour seals. We’ve got to get rid of them,’ ” he notes. “And that’s in the mistaken belief that it’s a fairly simple system, and that all the seals eat is salmon—that if we remove the seals, there’ll be more salmon. But like any problem that I’ve ever worked on, once you scratch below the surface you find out that it’s far more complicated than that.
“Just as an example, we don’t have any recent diet information, but what we know from the 1980s is that salmon made up four percent of the diet [of local harbour seals]. It’s hardly a ringing endorsement for seals eating all the salmon. The bigger items were herring at 32 percent and hake at 43 percent, and
what’s interesting about this is that hake is the largest fish predator of salmon smolt. So it could be that while the seals do eat adult salmon, the fact that they eat more of the salmon predators means that they have a net positive effect on salmon returns.”