Captain Pete and I searched high and low for cetaceans today, but in the end, we had to admit that our lucky streak had been broken. Spring is a time of transition in the Salish Sea. Some species of birds are only passing through on their way to breeding grounds. Marine mammal communities are also unsettled. Most humpback and gray whales are only brief visitors as they continue on their great migration between tropical breeding waters and northern feeding waters. A few of these sea monsters will settle around the San Juan Islands, however, and we’ll enjoy their presence throughout the summer.
At this time of the year, the uninitiated visitor will puzzle about the mysterious roaring sound that can be heard at Cattle Pass or Roche Harbor. The growling of Steller sea lions at their haul out sites on Whale Rocks and Green Point can carry on the breeze for a mile or more. But soon the wind will fall silent and the rocks will sit bare. In another month, most lions will hurrying to territories on the outer coast, pulled by an irresistible gravity: the urge to reproduce. But on this day, our guests were excited to have an up-close encounter with these beasts as they swam about the boat.
Some lions on shore had clear digits branded into their hide. Scientists mark animals in this way to record information about the life history of sea lions. By resighting individuals, we can learn how far they range, how long they live, and about the nature of relationships they form. At the Bonneville dam on the Columbia River, sea lions have learned to congregate during salmon runs. Salmon stall at the base of these blockages to their ancestral spawning habitat and, if their life cycle is to continue, they must find the fish ladder that will take them around the dam. Sea lions take advantage of the bottleneck of fish and can decimate already endangered runs of salmon.
When federally protected sea lions are euthanized by wildlife managers for their cleverness in exploiting the food source, public controversy ensues over how to balance conservation efforts with other goals. Hydropower, irrigation, and flood control are important considerations for a growing population; nonetheless, had citizens and legislators not passed and enforced the Marine Mammal Protection and Endangered Species Acts, my generation would likely have come of age in a world without humpback whales, seals, sea lions, or bald eagles. Whether we can act to protect the endangered southern resident killer whales, now numbering just 78 individuals, and their prey, Chinook Salmon, for future generations, remains a big question mark.
Naturalist, M/V Sea Lion
San Juan Safaris