What is an Anadromous Fish?
Anadromous fish migrate from freshwater where they hatch to the ocean where they spend most of their lives and grow large before returning to freshwater to spawn. Common anadromous fish include salmon, smelt, sturgeon, and lamprey.
For the purposes of NPAFC, anadromous fish that migrate into the Convention Area and are listed in the Convention Annex include chum, pink, sockeye, Chinook, coho, and cherry salmon, and steelhead trout.
What are Pacific Salmon?
Pacific salmon are anadromous fish of the genus Onchorhynchus spp. that spend most of their lives rearing in the ocean before returning to freshwater to spawn. Pacific salmon are semelparous, meaning that after spawning once, all the adults die. There are six species of Pacific salmon: chum, pink, sockeye, Chinook, coho, and cherry salmon.
Steelhead trout are also in the genus Oncorhynchus. A steelhead in the anadromous form of the rainbow trout and can make extensive oceanic migrations in the North Pacific. Unlike Pacific salmon, which are semelparous, steelhead are iteroparous, meaning they can survive spawning and repeat the migration to the ocean and return to freshwater to spawn more than once.
Chum salmon are the second most abundant species of Pacific salmon and originates both in Asia and North America. The fish spawn in streams and the fry migrate to the sea soon after emergence.
Immature chum salmon distribute themselves widely over the North Pacific Ocean, and the maturing adults return to the home streams in summer or autumn at various ages, usually from three through six years. Adults have been reported up to 108.8 cm in length and 20.8 kg in weight. Chum salmon die after spawning (semelparous).
How to distinguish the ocean
phase: Chum salmon do not have spots on the body or tail. The
tail fin has distinct silver streaks.
Pink salmon are the most abundant species of Pacific salmon and originates both in Asia and North America. Upon emergence, pink salmon fry migrate quickly to the sea and grow rapidly as they make extensive feeding migrations.
Pink Salmon have a fixed two-year life cycle. After eighteen months in the ocean, maturing fish return to their river of origin to spawn. Adults are the smallest Pacific salmon and range from 45-55 cm in length and 1.0-2.5 Kg in weight. Pink salmon die after spawning (semelparous).
How to distinguish the ocean phase: Pink salmon have large oval black spots on the back (dorsolaterally) of the body and on both lobes of the tail fin. Scales are very small. A large hump develops on the back of maturing males.
Sockeye salmon are the third most abundant species of Pacific salmon and originate both in Asia and North America. Typically juvenile sockeye salmon utilize lakes for rearing areas for one to three years after emergence from the gravel, but some populations can utilize stream areas for rearing and may migrate to sea soon after emergence.
Sockeye salmon spend 1-4 years in the ocean before returning to fresh water to spawn. Body size of adults is variable, but can range 45-60 cm in length and 1.6-3.2 Kg in weight. Sockeye salmon die after spawning (semelparous).
How to distinguish the ocean phase: Sockeye salmon do not have black spots present on the body or tail. Scales are regularly arranged in regular rows on the body. Flesh color is bright red.
Chinook salmon are the largest of the Oncorhynchus group and originate both in Asia and North America. Their life history includes an array of variations. All Chinook salmon die after spawning (semelparous).
"Stream-type" Chinook salmon spend one year as fry or parr in fresh water before migrating to the sea. Typically, this type will return to their natal river in the spring or summer several months prior to spawning.
"Ocean-type" Chinook salmon migrate to sea during their first year of life, normally within three months after emergence, and return to their natal river in the fall shortly before spawning.
The length of adults varies from 58 to 89 cm, or larger. The typical weight range of the Chinook salmon is 4.5 to 22.5 kg.
How to distinguish the ocean phase: Chinook salmon have small round black spots on the back and both lobes of the tail fin and black color along the base of the teeth in the lower jaw.
Coho salmon originate both in Asia and North America. Coho salmon fry generally remain in freshwater for one to two years and then migrate to the ocean. After approximately 18 months at sea, the fish return to their freshwater spawning areas.
The adult size is variable with lengths ranging from 40-88 cm and weights from 1.2-6.8 kg. Coho salmon die after spawning (semelparous).
How to distinguish the
Coho salmon have small black spots on the back that may be also present on
the upper lobe of the tail. Tail has bright but not well-demarcated
silver coloration. The caudal peduncle is relatively broad and the base
of the teeth in the lower jaw is white. Cherry Salmon
Cherry salmon originate only in Asia. Most of them mature at three or four years of age, after spending one or more years in rivers and one winter in the ocean. All anadromous cherry salmon die after spawning (semelparous).
They return to the natal river in March-May, spend the summer in the river, and move to headwaters for spawning in the fall.
The size of adults varies greatly, generally 50 cm or more in length and
2-2.5 Kg or more in weight.
Steelhead trout is the anadromous form of rainbow trout. Steelhead trout originate both North America and Asia. Most steelhead remain in freshwater for 2-3 years, spend 2-3 years in the ocean, and return to the natal river to spawn. Some steelhead may spawn more than once (iteroparous).
Typical sizes of adults range 50-58 cm in length and 1.4-6.8 Kg in weight.
How to distinguish
the ocean phase: Steelhead trout have small black spots present on the head, back and tail
fin. Silver marking on the tail is confined to the center area. The
is relatively small and the tail relatively large as compared to Pacific salmon.
The tail is not forked.