The keta salmon, scientifically known as Oncorhynchus keta, is a fascinating and ecologically important fish species native to the North Pacific region. Also referred to as chum, dog, or silverbrite salmon, it holds a significant place in both the natural environment and human culinary practices. While it may not possess the same prestige as the Chinook or the dramatic transformations of the sockeye, the keta salmon is a valuable resource with a unique set of characteristics.
Taxonomy and Nomenclature
The chum salmon (Oncorhynchus keta) is classified as an anadromous salmonid fish, meaning it migrates from saltwater to freshwater to spawn. It belongs to the Oncorhynchus genus, which encompasses all Pacific salmon. The scientific name Oncorhynchus is derived from the Greek words "ónkos" (lump or bend) and "rhúnkhos" (snout), aptly describing the hooked snout that male salmon develop during the breeding season.
The various common names attributed to this species reflect different aspects of its appearance or perceived qualities. "Chum" is perhaps the most widely used alternative name, while "dog salmon" might refer to the large canine teeth developed by spawning males, potentially used for fighting. The name "silverbrite" highlights the fish's shimmering, silvery coloration during its ocean phase.
Physical Characteristics
The keta salmon has a torpedo-like body shape with a slightly compressed form, ideally suited for efficient swimming. When not in their breeding colors, they exhibit shimmering bluish-green scales with black speckles. Adult chum salmon typically weigh between 9.7 and 22.0 pounds (4.4 to 10.0 kg) and measure around 23.6 inches (60.0 cm) in length. However, they can reach lengths of up to 40 inches and weights of up to 35 pounds.
Distinguishing features include 10 to 14 soft rays on their dorsal fin, 13 to 17 soft rays on their anal fin, and an emarginate (slightly notched) tail fin. The anal fin typically has 12 to 20 rays, which is more than the maximum of 12 found in European salmon species.
Read also: Comprehensive Bala Shark Guide
Spawning Morphology
As the keta salmon prepare to spawn, their appearance undergoes a dramatic transformation. Males develop a dark olive green or black coloration on their backs. The rest of their body turns grayish-red with black and red tiger-like stripes. A distinctive streak, resembling a bleeding gash, appears along their sides. Spawning males also develop prominently hooked lower jaws (kype) and hooked upper jaws containing long, sharp teeth, which may be used for competition with other males. Females, in contrast, develop a dark horizontal bar with some vertical striping.
Keta Salmon vs. Pink Salmon
The pink salmon, also known as humpback salmon, is another Pacific salmon species that can be confused with the keta. However, several key differences distinguish the two. Pink salmon are smaller than keta salmon, being the smallest of the North American Pacific salmon. They also have a more brilliant silver coloration and pinker flesh. During spawning, male pink salmon develop a pronounced hump on their backs, a feature absent in keta salmon. Furthermore, pink salmon lack the characteristic red slash on the side of the keta salmon.
Distribution and Habitat
The keta salmon boasts the broadest natural range of any Pacific salmon species. They are found throughout the North Pacific Ocean, from the coasts of Japan and Korea to the Russian Far East, British Columbia in Canada, and from Alaska to California in the United States. Their distribution extends as far north as the Alaskan Arctic and as far south as San Diego. They can also be found in Iran.
These fish exhibit remarkable migratory capabilities, traveling thousands of kilometers up rivers such as the Yukon in Alaska and Canada, the Amur in Northeast China and Russia, and the Mackenzie. Some chum even travel more than 3,200 km (2,000 mi) up the Yukon River.
The keta salmon's habitat varies depending on its life stage. They are born in intertidal zones and cold, freshwater streams with sandy or pebbly bottoms, typically during the late fall to winter or in summer. As juveniles, they migrate downstream to estuaries and nearshore marine environments, where they remain until they are large enough to venture into the open ocean. In the open ocean, chum salmon stay fairly high on the water column, rarely diving below 50 m (160 ft).
Read also: Sockeye and Keta Salmon: Key Differences Explained.
Life Cycle and Reproduction
The dog salmon undertakes one of the longest migrations of any salmon species to return to its natal stream. Once in freshwater, the female selects a suitable spawning site and excavates a nest called a redd, which is typically about 3 feet in diameter and 1.6 feet deep. The female lays eggs in the redd, and the male fertilizes them with milt. The female then covers the eggs with gravel to protect them. If the female mates with another male, she digs another redd. A female may spawn two or three times.
The eggs incubate for three to four months before hatching. After hatching, the juvenile chum salmon, known as fry, migrate downstream to estuaries and the marine nearshore within a few weeks after emergence from the gravel. Juvenile chum eat zooplankton and insects. They spend one to three years feeding and growing in the ocean before returning to freshwater to spawn.
After spawning, the adult keta salmon die, completing their life cycle. In some regions, they are the last salmon to spawn (November to January), while in others, such as Alaska, they are the first to spawn (June and August), followed by pink and coho salmon. They die about two weeks after they return to the freshwater to spawn. They utilize the lower tributaries of the watershed, tend to build nests called redds, really little more than protected depressions in the gravel, in shallow edges of the watercourse and at the tail end of deep pools. The female lays eggs in the redd, the male sprays milt on the eggs, and the female covers the eggs with gravel.
Diet and Predators
Keta salmon have a varied diet that changes as they mature. In freshwater, juvenile chum salmon feed on zooplankton and insects. In the ocean, their diet expands to include smaller fish, squid, mollusks, copepods, comb jellies, plankton, and tunicates such as sea squirts.
Keta salmon are preyed upon by a variety of animals, including bears, eagles, killer whales, seals, sea lions, and shorebirds. Bears often gather around streams to catch salmon as they migrate to their spawning grounds, while eagles scavenge on the carcasses of spawned-out fish.
Read also: Keta Salmon: A Comprehensive Guide
Commercial Importance and Sustainability
The keta salmon is commercially harvested using gill nets and purse seiners. In 2010, the registered total harvest of chum salmon in the North Pacific was approximately 313,000 tons, equivalent to 91 million fish. Japan accounted for half of the catch, with Russia and the United States each contributing about a quarter.
Despite its abundance, the chum salmon has historically been considered the least commercially valuable salmon in North America. Commercial fishers and sport anglers often do not prioritize targeting them due to their lower market value. However, this perception is changing as consumers and chefs recognize the keta salmon's unique qualities and versatility.
The population of keta salmon is estimated to be in the millions, with the Alaskan population alone likely exceeding 91 million fish. While the overall population is considered healthy, some specific populations, such as the summer-run chum of Hood Canal, are listed as threatened under the federal Endangered Species Act.
Culinary Uses and Nutritional Value
The taste of keta salmon is delicate and mild, making it a versatile ingredient in various culinary applications. It can be poached, pan-fried, baked, broiled, steamed, or even eaten raw as sushi or sashimi. Its lower oil content makes it suitable for roasting, as it helps to seal in its juices. Keta salmon is also a popular choice for tartars and marinades.
The roe (eggs) of the chum salmon is highly prized as salmon caviar. Salmon caviar is distinguished from sturgeon caviar by its red color and larger egg size. As chum salmon are more abundant than most sturgeon species, salmon caviar is often considered a more sustainable option.
Keta salmon is a healthy source of protein and omega-3 fatty acids, which are beneficial for heart health.
Keta Salmon Quality and Preparation
Keta salmon is often classified into three categories based on the color of its skin: bright, semi-bright, and dark. Shiny Keta has a metallic greenish-blue color that turns silver on the sides and belly during the fishing season. Semi-gloss Keta has darker stripes on the sides, and its skin and loin are less lustrous. Dark Keta features well-defined dark stripes on the sides that have turned a deep red hue.
Many recreational fishing locations for chum salmon are in freshwater or in saltwater near the mouths of spawning streams, which may be a reason why many sport caught chum are not of the same quality as ocean fish. Chum salmon mature very rapidly, and the fish in these locations are usually close to spawning and their table quality has substantially deteriorated. Because of this, smoke curing and kippering are often a preferred choice for preparing sport caught chum salmon.
Overcoming Negative Perceptions
Despite its versatility and nutritional value, keta salmon has faced some negative perceptions regarding its taste and quality. Some consumers find its milder flavor less appealing compared to other salmon species with higher fat content. However, this milder flavor can be an advantage for those who prefer a less "fishy" taste.
Chefs and home cooks are increasingly exploring innovative ways to prepare chum salmon to enhance its flavor and texture. Techniques such as marinating, smoking, and using flavorful sauces can elevate the taste of keta salmon and make it a delicious and satisfying meal.
tags: #silver #brite #keta #salmon #information