Silver Salmon
Order: Salmoniformes, Family: Salmonidae
Typically spend the first year of their life in fresh water. Upon moving to the ocean, growth increases dramatically. At about the third year, coho salmon reach maturity.
They weigh from 6 to 12 pounds and can be up to 38 inches in length.
Oncorhynchus kisutch are deep-bodied salmon with unique color characteristics. The dorsal surface is a metallic blue while the sides are a silver color. Black spots appear on the back and upper lobe of the caudal fin. A lateral line is also present. The line is curved toward the front of the fish and straightens out as it approaches the back of the fish. While spawning, the fish's back and belly turn dark.
Spawning males' sides develop a bright red line and their jaws become hooked.
I. DESCRIPTION:
- Typically spend the first year of their life in fresh water. Upon moving to the ocean, growth increases dramatically. At about the third year, coho salmon reach maturity.
- They weigh from 6 to 12 pounds and can be up to 38 inches in length.
- Oncorhynchus kisutch are deep-bodied salmon with unique color characteristics. The dorsal surface is a metallic blue while the sides are a silver color. Black spots appear on the back and upper lobe of the caudal fin. A lateral line is also present. The line is curved toward the front of the fish and straightens out as it approaches the back of the fish. While spawning, the fish's back and belly turn dark.
- Spawning males' sides develop a bright red line and their jaws become hooked.
II. GEOGRAPHICAL RANGE AND HABITAT:
- Oncorhynchus kisutch, commonly known as coho salmon, are primarily found in coastal waters. Coho salmon do not range widely in the open ocean like that of many other salmon species.
- Oncorhynchus kisutch are also found in fresh water, during their first year and later while spawning. They are found in fresh streams of the North Pacific, ranging from Baja, California to Alaska.
III. DIET:
- In fresh water streams and rivers, juvenile coho salmon defend territories and compete for limited feeding sites with other fish. In order to attain these feeding sites, they may charge or chase other fish away, as growth and fitness depend on it.
- Coho salmon attack prey by sprinting and striking. They are able to maneuver well in order to capture prey. In fresh water, coho eat insects and smaller fish.
- When they move to the ocean they begin to grow rapidly due to the abundance of food. Once these fish reach the ocean their diet changes to other fish, such as herring and squid.
IV. LIFE CYCLE/SOCIAL STRUCTURE:
- At three to four years of age, coho salmon reach sexual maturity. From September to October, coho swim to the fresh water streams where they were born (up to 400 miles).
- Once the fish reach their natal site females dig a nest in a gravel-type area. After the nest is made a female and one male (occasionally 2) breed. In this breeding, the female lays her eggs and the male's sperm is spread over them, thus fertilizing them. After fertilization has occurred, the eggs are buried by other female coho that are digging their nests.
- Following reproduction, males and females die, giving the waters more nutrients.
- Larvae hatch 6-8 weeks after fertilization. The larvae remain in the gravel for 2-3 weeks. Coho live in streams or rivers for about a year until they move to the ocean.
V. SPECIAL NOTES/ADAPTATIONS:
- Oncorhynchus kisutch make a good meal. Often, coho are either sold frozen or canned by commercial fisherman. Twice as many coho salmon are harvested commercially in North America than in Asia. During the late 1950's about 10 million coho salmon per year were caught. These numbers declined to 4.5 million coho per year in the 60's and have now risen to about 10.5 million coho per year. Fishing for coho is also an important sport for trollers and flyfisherman.
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