Salmon

Salmon, a valuable food and game fish. Salmon are normally found in temperate or Arctic waters of the Northern Hemisphere. There are seven species of salmon—one found in the Atlantic Ocean and six in the Pacific.

Most salmon are anadromous—that is, the adults migrate into freshwater rivers or lakes to breed. Salmon are famous for the runs they make as they return to their place of birth to spawn. Leaping high into the air to surmount obstacles, the fish fight their way upstream to the headwaters of their native rivers. It is at this time, when the fish are in prime condition, that the catch is taken by sport and commercial fishermen. (For record catches, table of freshwater fishing records.)

A salmon is a bony fish because its skeleton is made mostly of bone. The skull, backbone, and ribs are made of bone. Salmon and most other bony fish also have many thin bones, called rays, inside their fins.

Skull bones form the frame for a salmon’s head. The skull bones include the upper and lower jaw and the brain case. Bony plates protect the gills that are located on the side of a salmon’s head.

The backbone forms the frame for the rest of a salmon’s body. The backbone has many separate pieces of bone called vertebrae (VUR tuh bree). The ribs are attached to the vertebrae.

Bony fin rays form the frame for a salmon’s fins. Fins help the fish swim and keep its balance.

Fish are vertebrates (VUR tuh brihts), which are animals with backbones. Fish live in water and usually breathe with gills. A bony fish is a fish whose skeleton is made mostly of bone. Salmon and trout are bony fish. Bass, catfish, flounder, barracuda (bair uh KOO duh), and seahorses are bony fish, too.

Altogether, there are about 24,600 kinds of fish. Most of these fish have bones. In fact, there are about 23,700 kinds of bony fish. But some fish, including sharks and their relatives, have no bones at all. Instead they have skeletons made of a tough, rubbery material called cartilage (KAHR tuh lihj).

Bony fish live almost anywhere there is water. They are found in chilly waters in the Arctic and in warm waters in the tropics. Bony fish swim in streams, rivers, lakes, and oceans. Salmon are bony fish that usually grow up in streams, but they spend their adult lives in the ocean.

Most adult salmon live along the coast of the North Pacific Ocean. These include the chinook (chuh NOOK), chum, coho, pink, and sockeye salmon. Amago and cherry salmon are found in the Pacific waters of eastern Asia. Only one kind of salmon, the Atlantic salmon, swims in the Atlantic Ocean.

A few groups of salmon live their entire lives in northern lakes and streams that don’t flow to the ocean. People have released freshwater salmon into other lakes around the world. There they have become popular sport fish.

Adult salmon are shaped a bit like torpedoes so that they can easily dart through the water. An adult salmon has six kinds of fins. The smallest fin is called the adipose (AD uh pohs) fin. It’s located on top of the body, near the caudal (KAW duhl) fin.

Hard, shiny scales cover the salmon’s skin and protect its body. Most adult salmon found in the ocean have dark-colored backs and silvery-white bellies.

Typical salmon grow to a length of about 2 feet (61 centimeters) and weigh about 10 pounds (4.5 kilograms). But chinook salmon can grow much bigger. Chinook salmon can reach 3 feet (91 centimeters) long and weigh over 100 pounds (45 kilograms). That’s why chinook salmon are also known as king salmon.