Salmon

The salmon family Salmonidae comprises numerous landlocked and anadromous species (Fig. 7). They are found in most waters of the northern hemisphere and dominate the northern waters of North America, Europe, and Asia. This family is made of of three subfamilies, the Salmoninae (salmon, trout, char), the Coregoninae (whitefish), and the Thymallinae (grayling). A common feature among all species is the adipose fin located on the dorsal surface between the dorsal and caudal fins. While representatives of the Coregoninae and Thymallinae belong to this family, the term salmon is usually applied to the salmon and trout of the Salmoninae. This article deals with only those species that are commonly referred to as salmon, which includes species in the genera Oncorhynchus and Salmo. Even this restriction does not eliminate the confusion between common names and the scientific classification. The Atlantic salmon, for example, is strictly classified as a trout in the genus Salmo. The rainbow trout, on the other hand, has just recently been transferred from the genus Salmo to Oncorhynchus, but it continues to be called a trout. The species covered here include the Pacific salmon species, the rainbow trout, and the Atlantic salmon.

The anadromous species spawn in fresh water where the eggs incubate and where the young spend varying lengths of time. It is common for adults to return to the streambed where they were hatched. During the sexual maturation process, the typically silver fish begins to darken and takes on various colors including black, brown, orange, and red. There is usually a dramatic transformation of the shape of the head and in some instances, the whole trunk. The head of the male usually elongates and there is a pronounced development of teeth. The chum salmon, for instance, develops a large hump back during this process. Many species do not feed once they enter fresh water and begin their migration to their spawning grounds. The spawning process culminates a long journey, sometimes covering thousands of miles, and normally ends in death for the Pacific salmon. The trouts, on the other hand, usually recuperate and may return to spawn a number of times. The Pacific salmon, Atlantic salmon, and steelhead trout are anadromous. The landlocked salmo-nids discussed in this article include the rainbow trout and the kokanee salmon. While these are the natural life cycles, some species can be grown entirely in fresh water. For example, rainbow trout can be grown quite successfully in seawater netpens and the coho and pink salmon can spend their entire life cycle in fresh water.

female can exceed 2.5 million young. The young off the Washington coast are born in June.

Atlantic Redfishes

There are several species that belong to Sebastes in the Atlantic. Four occur in the North Atlantic Ocean, three in the western North Atlantic and one (Sebastes viviparous) in the eastern North Atlantic. The three species of Atlantic redfishes found off the North American coast are the Acadian redfish (Sebastes fasciatus), the golden redfish (Sebastes marinus), and the deepwater redfish (Sebastes men-tella). They are all commercially valuable as food fishes, although specific fisheries for each species do not exist. They are, rather, fished as a group and marketed as fresh and frozen fillets under the name of ocean perch. The deep-water redfish probably makes up the majority of the catch off the Newfoundland-Labrador coast, while the Acadian redfish is the main species in the commercial catch of redfish off the Georges Bank-Gulf of Maine region. These fishes are caught with otter trawls.

The Acadian redfish has an orange-red body with red fins, with the pelvic and anal fins having a particularly deep red color. There are green-black blotches below the dorsal fin and on the posterior part of the gill covers. There may be green iridescent flecks on the body above the lateral line. The deepwater redfish is bright red all over. The golden redfish can be colored either orange-yellow or gold-yellow.

The distribution of the Atlantic redfishes extends from Iceland, south to about Virginia on the U.S. coast. The golden redfish is more common in the northern range of this distribution but less common in North American waters compared to the Acadian redfish or the deepwater redfish. The golden redfish is common off Greenland, Iceland, Norway, and in the southern Barents Sea. The deepwater redfish has the broadest distribution of the three redfishes and occurs throughout the North Atlantic range of this genus except the North Sea and the Gulf of Maine. It is also found farther offshore than the other two species. The Acadian redfish may be considered the North American redfish because it is most common along the Canadian continental shelf and southward, particularly along the Georges Bank and in the Bay of Fundy and Gulf of Maine waters. The Acadian redfish occupies the shallowest waters of the three species, found most often at depths between about 130 and 370 m. The golden redfish is found from about 300 to about 370 m. The deepwater redfish is found in waters about 350-700 m.

About half of the populations of the Acadian and deep-water redfishes mature at about 19 cm and 30 cm for males and females, respectively. The female golden redfish matures at about 41 cm. There is evidence suggesting the young hatch inside the female golden redfish in April and are born between April and May. The Acadian and deep-water redfishes hatch their young between March and June and release their young between March and June. A study in the Gulf of Maine showed that the Acadian redfish about 30 cm retains about 50,000 fertilized eggs and releases about 15,000 to 20,000 living young. The young of the Acadian redfish grow to be about 8 cm in the first year and grow an average of about 2.5 cm each year up to about 10 yr of age, declining in rate after that. The growth rates in males and females seem to be about the first 20 yr of life.

The Atlantic redfishes, like the Pacific Sebastes, grow very slowly. Sections of the otoliths have been used to age these fishes. That data show that the golden and deep-water redfishes can live to be 48 yr old. This depends on the population. The populations of Acadian redfish in the Gulf of Maine may live up to 20 yr and grow to a maximum size of about 46 cm and 1.4 kg.

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