Pink salmon (Oncorhynchus)
While at sea, the pink salmon is silvery in color, with a bright metallic blue above. Several black oval spots cover the entire tail fin, while large spots appear on the back and the small adipose fin. When pink salmon enter spawning streams, the males appearance changes to pale red or pink on the sides, with brown to olive green patches, and the females becomes olive green above with intermittent dark and pale patches below. Young pink salmon are entirely silver and lack the dark vertical bars that other young salmon species possess. Young and old pink salmon have small, deeply embedded scales.
The pink salmon gets its name from its pink flesh, compared to white or red of other salmon, and several common names refer to the shape the males take on during the spawn. Males develop a large hump from behind the head to just ahead of the dorsal fin. They also develop a pronounced hook shape in their upper jaw, known as a kype.
Early in their freshwater spawning runs, pink salmon consume a variety of insects, although once actual spawning begins, they do not feed at all. Juvenile fish feed on plankton, larval fishes, and occasional insects. At sea, adults feed primarily on plankton, crustaceans, small fish, and squid.
The pink salmons native range extends throughout the northern Pacific and Arctic coastal waters, from the Sacramento River in northern California northeast to the Mackenzie River in Canadas Northwest Territories, and from the Lena River in Siberia to eastern Korea. They also inhabit waters throughout the Aleutian Islands, the Bering and Okhotsk Seas, the Sea of Japan, and the island of Hokkaido, Japan, as well rivers that flow into these waters.
Pink salmon have been introduced to the western coast of Lake Superior and as far east as Newfoundland, and both regions currently maintain modest populations. Though introduced accidentally into Lake Superior, they have been known to spawn in tributaries of Lake Huron. After introduction into Newfoundland, there have been sporadic reports of pink salmon in Nova Scotia, Labrador, and Quebec.
Pink salmon are anadromous, meaning they spend parts of their life in the ocean but return to their natal freshwater stream to spawn. They spend their first several months in the rivers and streams in which they hatch. Almost immediately after emerging from the gravel, young pink salmon begin swimming downstream toward the ocean during the spring.
Following entry into salt water, juvenile pink salmon move along close to shore in dense schools near the surface. In their first year they remain in shallow, near-shore nursing areas not far from the rivers they left. As adults, they are known to distribute over the ocean in nearly identical patterns year after year, and in general stay near the shore more than other species of salmon. After 18 months at sea, adult pink salmon return to their native rivers during the fall, seeking out coarse gravel or rubble bottoms on which to spawn.
- The all-tackle world record is 13 pounds, 1 ounce, taken from the St. Marys River in Ontario, Canada, in 1992.
- Pink salmon can cross-breed with chum salmon.
- Pink salmon encounter numerous natural and human induced threats to their survival, such as run-off of herbicides and pesticides, dams, urban development, and industrial waste. In addition, shoreline development and the filling of marine wetlands can significantly affect the near-shore environment, negatively impacting pink salmon before they head out to the ocean.