Commercial Fisheries
Most of the commercial catch is made at or near the mouths of rivers as the fish approach the coast. The fish are generally caught with gill nets or purse seines, or by trolling. Most of the Atlantic salmon catch is marketed fresh or frozen; small quantities are canned, pickled, or smoked. About half of the Pacific catch is canned. In modern canneries, nearly all the salmon are cleaned and canned by machinery. In some smaller canneries the cutting and several other operations are done by hand. Some floating canneries are also in operation. Salmon eggs are used to make red caviar. They are also used for bait.
Salmon are among the most valuable fish caught, although the size of the catch by weight is relatively small. They are used almost exclusively for human food, and much of the world catch is canned or otherwise processed. The Atlantic salmon normally provides 8 to 16 per cent of the total world salmon catch, with Norway, Great Britain, Denmark, and Canada the leading nations. The Pacific salmon catch is taken by the United States, Japan, Russia, and Canada.
Overfishing and water pollution have caused a decrease in the number of salmon. In addition, dams, particularly hydroelectric dams on the Columbia and Snake rivers, block salmon from upstream spawning grounds. Many young salmon are killed in turbines at hydroelectric plants. A number of conservation measures are used to protect salmon populations. One of the major conservation measures is the artificial propagation of salmon. Millions of salmon eggs are hatched in hatcheries maintained by state and federal organizations. Fish ladders (series of pools arranged like steps) allow adult salmon to swim upstream over or around dams. At some hydroelectric plants, there are underwater screens that divert young salmon away from turbines and into bypass channels. Despite these and other conservation measures, some species, especially the chinook and the sockeye salmon, continue to decline in numbers.
The closest relatives of salmon are trout. Trout and salmon belong to the same family, or group, of bony fish. They have similar, torpedolike shapes. Both fish have small adipose fins. Some trout and salmon look so much alike that they are often mistaken for each other.
The best-known trout is the rainbow trout. It is closely related to salmon that live in the Pacific Ocean. Like salmon, rainbow trout spawn in streams. Some rainbow trout also travel to the ocean. A rainbow trout that makes this journey is called a steelhead. Most rainbow trout, however, stay in freshwater streams all their lives.
Rainbow trout are named for their colorful reddish bands that run along their sides. These trout also have black spots on their upper bodies and tails. Rainbow trout that stay in streams usually weigh around 2 to 5 pounds (1 to 2.3 kilograms).
Salmon face many dangers. Birds and fish eat salmon eggs, fry, and smolt. Some salmon never get to the ocean because they die along the way. Water pollution is also dangerous for salmon, especially smolt.
A salmon that reaches the sea may be too big for herons or other small birds, but it had better watch out for eagles or ospreys. An adult salmon’s other enemies include bears, sea lions, seals, and killer whales. Many salmon are also caught in large fishing nets.
Salmon that survive in the ocean grow bigger. They eat many sea animals, including shrimp, squid, and other fish. Some kinds of salmon may stay and grow in the ocean for only six months before they return home to spawn. Other kinds may live in the sea for six years or more.
All bony fish, except the largest ones, are always in danger of being eaten by other fish and water animals. Many fish are also in danger of being caught by people.
Salmon is a popular food for people. Each year, fishers from Canada, Norway, Japan, the United States, Chile, and Russia catch millions of salmon. As a result, some types of salmon are now endangered.
To protect the fish, laws now limit salmon fishing in some parts of the world. This allows many salmon to survive in order to spawn. Also, thousands of salmon are now raised in hatcheries and then released into rivers and streams.
Salmon belong to the family Salmonidae. The Atlantic salmon is Salmo salar. It is of the same genus as true trout. Pacific salmon belong to the genus Oncorhynchus. The chinook is O. tshawytscha; the sockeye, O. nerka; the coho, O. kisutck; the pink, O. gorbuscha; the chum, O. keta; the cherry, O. masou.
