【正确答案】 SALMON Every year millions of salmon swim from the ocean into the mouths of rivers and then steadily out of rivers. Passing through waters, around rocks and waterfalls, the fish finally reach their original streams or lakes. They dig up nests in the riverbed and lay their eggs. Then, exhausted by their journey, the parents salmon die. They have finished the task that the nature has given them. Months or years later, the young fish start their trip to ocean. They live in the salt water for two to seven years, until they too are ready to swim back to reproduce. Their life cycle helps man provide himself with a basic food—fish. When the adult salmon gather at the river mouths for the annual trip of the rivers, they are in the best possible condition. And nearly every harbour has its salmon fishing fleet ready to catch thousands for markets.