Latin name

Oncorhynchus gorbuscha

Other names

Humpback salmon, humpy, fall salmon, pink, humpback; French: saumon rose; Japanese: karafutomasu, sepparimasu.

Identification

Pink salmon are known as "humpback" because of their distorted, extremely humped appearance, which is caused by a very pronounced, flattened lateral hump that develops on the back of adult males before spawning. This hump appears between the head and dorsal fin and develops by the time the male enters the spawning stream, as does the hooked upper jaw, or kype. At sea, pink salmon have a silvery color with a bright metallic cast. There are many black, elongated, oval spots throughout the caudal fin, and large spots on the back and fat fin. When the pink salmon move to the spawning streams, the bright appearance of the male changes to pale red or "pink" on the sides, with brown or olive green spots. Females become olive green on top, with dusky stripes or spots, and pale underneath. Scales are fine, thin, rounded: 143-230 scales in lateral line.

Distribution

Pink salmon inhabit the coastal waters of the Pacific Ocean in the Northwest Territories of Canada. It was introduced to Newfoundland and the west coast of Lake Superior and currently maintains a population in those areas. Since its introduction to Newfoundland, pink salmon have been reported in Labrador, Nova Scotia, and Quebec. Occurs in the Arctic Ocean as far west as the Lena and east to the Mackenzie River. Along the Asian coast, it reaches as far south as the Korean Peninsula and the shores of Hokkaido and Honshu. It is introduced into the rivers of the Barents and White Seas. At present, it is found off the European coast of Russia, Norway, Sweden, and Iceland.

Habitat

A migratory fish making a spawning migration. These anadromous fish spend 18 months at sea and then make their spawning migration to the river or stream where they were born, although they sometimes use other streams as well. They typically migrate up to 40 miles and sometimes farther into coastal waters.

Size

The average pink salmon weighs 3 to 6 pounds and is 20 to 25 inches long, although these fish can grow to 15 pounds and 30 inches. The world record for all-tackle fishing is a 14-pound, 13-ounce fish caught in Washington, D.C., in 2001. Pink salmon live only two years. Of the Pacific salmon, pink salmon have the highest growth rate. By the summer of its second year, it matures at an average length of 47-50 cm. Male pink salmon are larger than females. The greatest length is 68 cm and weight is 3.8 kg.

Life history and Behavior

Pink salmon are often called "fall salmon" because of their late spawning season. In Alaska, it runs from July to mid-October. Adults die shortly after spawning. Almost all pink salmon mature within two years, which means that odd and even year populations are separate and essentially unrelated.

Food and feeding habits

The main components of the pink salmon's food are crustaceans (Hyperiidae, Euphausiidae), cephalopods and winged mollusks, as well as juvenile fish. They do not feed during spawning.

Reproduction

Spawning usually takes place in river spawning grounds, at a depth of 20-40 cm to 90-100 cm. The ground of spawning grounds in most cases consists of medium-sized pebbles with a slight admixture of sand. Current velocity at the spawning grounds is 0.3-0.7 m/s, pH is normally no lower than 7. Water temperature during spawning ranges from 6 to 13.5°С. The spawning period is from late June to September, sometimes early October. The earliest spawning period is for pink salmon in the Amur basin (from the end of June to mid-September). From the end of July, pink salmon spawn in the rivers of Primorye and Sakhalin. In early August, pink salmon spawning begins in the rivers of Kamchatka and the northern coast of the Sea of Okhotsk. The female digs a nest in the gravel that is 20-28 cm deep and 30-60 cm in diameter and lays her eggs there. The female fills the fertilized eggs with soil and arranges a spawning mound over them. A spawning mound contains 1-2 clutches, 2-4 m long and 1.1-1.5 m wide. One clutch contains 200 to 900 eggs. After spawning, the female guards the spawning mound from other females for some time, then she is swept away by the current and dies. Fertility is from 0.6 to 2.9 thousand, usually 1.2-1.8 thousand eggs. Eggs are bottom-dwelling, not adherent. Mature ovarian eggs are 6 mm in diameter. The development of eggs in the ground occurs when the water temperature gradually decreases from 6-13.5 to 1.0-0.5°С. The larvae emerge from the eggs 90-120 days after fertilization. The larvae remain in the soil of spawning grounds until spring. In May-June, the fry roll into the sea at 30-40 mm in length, mostly during the darkest hours of the day.

Interesting facts

Fish sometimes change shape during the spawning season. Male pink salmon in particular change dramatically. In the ocean, where they spend most of their lives, they are slender fish with streamlined, spindle-shaped bodies. When they leave the ocean and enter the rivers to spawn, the males turn into freaks: their jaws are elongated and hooked, and a large hump grows on their backs. Some ichthyologists believe that this change in body shape is related to a change in their lifestyle. In the ocean, pink salmon need to swim fast to catch fast ocean fish. In the river, however, this fish does not eat. Here, the male's job is to build a nest and protect the eggs. This requires agility, not speed. Calculations have shown that in the river the agility of the future father really increases. However, it is premature to say that this is the reason for his hump. After all, other fish that build nests and protect eggs and fry do not grow a hump!