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Many hazards stand between a salmon egg and adulthood. Sometimes these hazards are natural, and sometimes they come from people. To learn more about the risky life of a salmon, complete this story by filling in the blanks. There are 15 female Pacific salmon in a stream. Each one lays 7,000 eggs in shallow gravel depressions they have scooped out in the streambed. There are ______ eggs in all. Once the eggs are deposited, male salmon fertilize them. In this stream, only half of the eggs are fertilized. There are ______ fertilized eggs, each with a chance of hatching. A new road is built near the stream. A large rainstorm comes along, and mud and gravel wash into the stream, killing 4,500 eggs. Now there are ______ eggs. It is a hot summer, and lightning starts a forest fire. Ashes drop into the stream, smothering another 3,500 eggs. The remaining eggs hatch, making ______ young salmon. After two weeks, the tiny salmon begin their journey downstream to the sea. Chemicals from fields and lawns are washed into the stream by a storm and kill 15,000 salmon. Now there are ______ youngsters. The young salmon finally reach the sea. They try to avoid predators, but 11,000 of them are consumed by seals, sea gulls and larger fishes. There are now ______ salmon. People in fishing boats catch another 11,500. Two years after their birth, there are ______ fish left ready to return home to spawn. As they near the entrance of the same river they swam down, a grounded ship has dumped oil into the ocean. The spill kills another 5,400 salmon, leaving ______ to swim upstream. Hungry eagles and bears are waiting for the returning salmon and eat 700 of them. This leaves ______ fish headed towards the fish ladders around the dam. While the fish are making their way up the ladder, fishermen and raccoons take another 250 of them. ______ salmon remain. As they head towards their final hurdle, a waterfall, the now battered salmon begin jumping up the falls. Some of them become too exhausted, and 638 die. ______ salmon arrive at their original streambed to spawn and begin the cycle again.
Adapted from Discovering
Salmon: A Learning and Activity Book by Nancy Field and Sally Machlis. |
