Any carnivore that eats a lot of salmon will raise the proportion of heavy nitrogen and carbon in its body. So will algae, aquatic insects and fish that take up nutrients released from decaying salmon carcasses. In 1985 Kline began to track nutrients as they moved from dead sockeye into the plants and animals of Iliamna Lake. He found that salmon play an important part in fuelling the lake's food web. They provide up to 90 per cent of the nitrogen in algae that live on the lake bottom, and up to 70 per cent of the nitrogen in plankton and juvenile sockeye.
Pacific salmon hatch out of eggs laid in the gravel of stream beds or lake shores.
They migrate out to sea, where they spend most of their adult lives before returning to their freshwater birthplaces to spawn and die. The sockeye salmon that Kline studied migrate in dense groups and spawn in lakes. By contrast, coho spawn in steep headwater streams, where they disperse and defend mating territories. Around the time that Kline began his studies in Alaska, Jeff Cederholm, a salmon biologist with the Washington Department of Natural Resources, became interested in the possibility that coho make an important contribution to the nutrients of their spawning streams. Nevertheless, Cederholm's idea was not well received.