Every year thousands of sockeye salmon meet their end in Hansen Creek, a pebble-strewn tributary of Lake Aleknagik in southwestern Alaska, whether from old age or at the paws and jaws of a brown bear. Either way, they’re almost certainly destined to rot away on the north-facing bank of the stream.
That’s because professors, researchers and students have been systematically tossing their carcasses to that side of the creek for the last 20 years. The scientists count and measure the carcasses and then toss them out of the streambed and up into the forest using wooden poles with metal hooks on the end, called gaffs.
In total, they tossed about 295 tons of salmon onto Hansen Creek’s north-facing bank to avoid double counting surveyed fish. In doing so, they have created a unique opportunity to study exactly how salmon fertilize the forest.
Over the past 20 years, researchers across the Northwest have shown that salmon play an essential role in forests: Trees next to salmon-bearing streams appear to grow better than their salmon-deprived counterparts, and the nutrients salmon bring from the ocean make their way into the needles and wood of trees.
But this experiment, described in a recently published paper, led by Tom Quinn, a professor in the School of Aquatic and Fishery Sciences at the University of Washington, proves a basic fact: More salmon means faster-growing trees. [Read more…]