Chum salmon, scientifically known as Oncorhynchus keta, is a species of fish that belongs to the salmon family, Salmonidae. It is also commonly referred to as dog salmon due to its large, sharp teeth and aggressive nature during spawning season. Chum salmon are an anadromous species, meaning they migrate from saltwater to freshwater to reproduce.
Chum salmon are known for their streamlined bodies and metallic greenish-blue coloration along the back, transitioning to silver on the sides and belly. They have a forked caudal fin and small, closely spaced scales covering their body. On average, adult chum salmon measure about 60 to 90 centimeters (24 to 35 inches) in length and weigh around 4 to 10 kilograms (8.8 to 22 pounds). However, some individuals can reach lengths of up to 120 centimeters (47 inches) and weigh over 15 kilograms (33 pounds).
These remarkable fish have an average lifespan of about 3 to 5 years, although some individuals can live up to 7 years. Chum salmon undergo several physiological changes as they approach their spawning grounds. Their bodies become more robust, and the males develop a pronounced hooked jaw, known as a kype, along with sharp teeth. This adaptation aids in fighting other males for dominance during the spawning process.
Chum salmon fishing is highly influenced by various environmental factors, including the time of day, weather conditions, and the season. Different seasons offer different opportunities for anglers to target this species.
In spring, chum salmon can be found in coastal waters, preparing for their migration upstream. During this time, early mornings and evenings prove to be the most productive for fishing. As summer arrives, chum salmon begin their upstream journey, and fishing opportunities expand to rivers and estuaries. Daytime fishing can be successful, especially during overcast or slightly cloudy conditions.
In autumn, chum salmon enter their spawning phase, and rivers become the primary target for anglers. Early mornings and late afternoons are ideal times for fishing, particularly when the water temperature is slightly cooler. Winter is a challenging time for chum salmon fishing, as they are less active and tend to stay closer to the ocean. However, with the right techniques and persistence, anglers can still have success during this season.
Chum salmon have a broad geographic distribution, inhabiting the northern Pacific Ocean and adjacent freshwater systems. They are found along the coasts of North America and Asia, ranging from the Arctic Circle to the Korean Peninsula. Chum salmon populations can be found in countries such as the United States (Alaska, Washington), Canada, Russia, Japan, and South Korea.
These fish are known for their remarkable homing instincts, returning to the same rivers and streams where they were born to spawn. This behavior ensures the perpetuation of local populations and contributes to the overall genetic diversity of the species.
Chum salmon exhibit an annual spawning migration, returning to their natal rivers from the ocean. The timing of their spawning depends on various factors, including water temperature and the availability of suitable spawning grounds. Typically, chum salmon spawn in late summer or autumn.
The water temperature during spawning ranges between 10 to 14°C (50 to 57°F). Females dig nests, called redds, in gravel beds within the river. After spawning, the female covers the eggs with gravel, providing protection from predators and ensuring oxygenation. The eggs hatch in approximately 3 to 5 weeks, and the newly emerged fry remain in the river for a period before migrating downstream to the ocean.
Chum salmon are opportunistic feeders and exhibit a varied diet throughout their life stages. As juveniles, they primarily feed on small invertebrates and zooplankton. Once they transition to the ocean, their diet expands to include a wide range of prey items, such as small fish, shrimp, and squid.
During their upstream migration for spawning, chum salmon reduce their feeding activity. They rely on energy reserves accumulated during their time in the ocean. This behavior helps them conserve energy and prepare for the challenging reproductive process.
Chum salmon play a crucial ecological role in the aquatic ecosystems they inhabit. As they migrate upstream, they transport marine-derived nutrients from the ocean to freshwater habitats. These nutrients contribute to the overall productivity of the ecosystem, benefiting various organisms, including insects, plants, and other fish species.
Furthermore, chum salmon serve as a vital food source for numerous predators, such as bears, eagles, and other fish species. Their abundance and availability during spawning seasons support the stability and health of these predator populations.