Salmon
Salmon is one of the most well-known endangered species that depends on the San Francisco Bay. Both Chinook and Coho salmon are threatened and endangered species in the San Francisco Bay watershed.
The Chinook salmon has a blue-green back, with silvery sides, black spots, and a white belly. On average, Chinooks grow to be about four feet long and weigh 24 pounds. Some Chinook have been measured as long as five feet and weigh more than 100 pounds!
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(California Dept. of Fish and Game) |
Coho salmon look very similar to Chinook salmon, with the same blue green back, silver sides, and white belly. Cohos are usually smaller than Chinook and have fewer spots on the upper part of their bodies. Adult Cohos can grow to 30 inches long and weigh up to 30 pounds, though their average weight is about 10 pounds.
Young salmon feed on terrestrial and aquatic insects, and aquatic invertebrates, such as crabs or crayfish. As they grow in size, salmon survive primarily by eating smaller fish.
Salmon are born in fresh water streams. When they are big enough, they migrate downstream, spending time in San Francisco Bay before swimming out to the Pacific Ocean, where they live the majority of their lives. At the end of their lives, salmon swim back upstream to the place where they were born. Here, they spawn, then die.
Salmon are also important contributors to the ecosystem. Young salmon are an important food source for other fish and birds. Dolphins, seals, sea lions, sharks, and humans eat adult salmon from the ocean. Finally, along the streams where they spawn, their decaying bodies are an important source of nutrients for both the soil and other animals.
Because salmon live in so many different ecosystems throughout their lives—streams, the Bay, and the ocean—and because they require very specific conditions to survive and reproduce—shady streams, cool water, and protected wetlands—salmon are called an indicator species. The health of salmon populations can indicate the health of our watershed, Bay, and ocean.
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