Scientific name: Oncorhynchus kisutch
Other names: Coho Salmon; Silverside; Silvers.
The names origin remains a mystery.
Although these salmon come from an ancestor trout, which led to the current species: Chinook, Coho, Pink, Chum and Sockeye; Coho salmon is more related to Chinook as they share some historical patterns and genetic characteristics.
Weight and measures: When the specimens return to the river where they were born, their average weight is between 2.7 to 4.3 kg (61-71 cm); however, the world record was caught in Salmon River (one of the Ontario´s Lake tributary), a fish of 15.1 kg and 99 cm long.
Habitat and life cycle: It is an anadromous fish, i.e. they spend most of time at sea and then return to the river where they were born to spawn. They spend between 2 and 4 years at the sea, although there are records of 6 years. This fish lives in the Pacific Ocean, and is the second in abundance after Chinook salmon.
Young coho spend one to two years in their freshwater natal streams before heading out to the sea; by that time they are already 10 to 13 cm long. After that they grow fast due to food availability, reason why after 18 months of being at sea they return to their natal rivers weighing between 2.7 and 4.3 kg. There are some exceptions to the common behavior as there are a few fish that leave fresh water in the spring, spend summer in brackish estuarine ponds and then return to fresh water in the fall. As regards spawning, it occurs between September and October in small streams with gravel bottoms. This species migrate 160-320 km into rivers to spawn; however, some coho salmon have been found after having swum between 800 and 2250 km (Yukon, Columbia and Skeena rivers).
Common phenomenons within the coho spawning population are "jack coho" that return to their natal rivers after a couple of months at sea, with an average length of 30 to 41cm, and die after spawning or even die despite not having spawned yet. In this aspect, jack Coho’s can be compared with Atlantic salmon fish that spend a year at sea during winter before they go back to freshwater rivers to spawn, not necessarily dying on this case.
Appearance: During their ocean phase, Coho have silver sides and dark blue backs. During their spawning phase, the jaws become hooked. They develop bright red sides, bluish green heads and backs, dark bellies and dark spots on their backs after they go in to fresh water. They are frequently mistaken as Chinooks.
Diet: During their estuaries and marine life stages, coho´s are important predators of other fish and crustaceans. Once they reach freshwater they feed on various aquatic and terrestrial invertebrates and they stop for spawning.
Sport: This is one of the most sought-after salmon species by fly fishing fishermen. Like other salmons, they attack the flies during their migration through fresh water to spawn. Even though there is no scientific explanation for such behavior, it could be associated with increased hormone levels that cause an increase in aggressiveness. Coho´s are highly combative and characterized by their colossal jumps.