The most distinguishing characteristic is a red-orange streak under the lower jaw, the source for the fish's moniker. It is shaped like most other trout as it has an elongated and slender body, while its colors vary depending on habitat and location: gold, green, and black are all hues that have been recorded with all the different subspecies.
Saltwater species grow much larger, generally the 20-pound (8 kg) range being the ceiling, while freshwater-only varieties don't grow to much heavier than 2 pounds (1 kg).
Depends entirely on location, but typically cutthroat trout grow fairly slowly. Coastal trout that live downstream tend to grow faster than those more upstream as more food is readily available in most situations.
Cutthroat trout are commonly found in Western United States and BC, Canada. The sea-run subspecies rarely get much farther inland than 100 miles (160 km), ranging all along the Pacific coast from California to BC. Freshwater breeds are found throughout the Pacific Northwest and south in the Great Basin and Rocky Mountains.
Cutthroat trout stick primarily to streams and rivers. Even ocean species stay very close to shore so they can use the current of coastal streams to catch their food. Cutthroats tend to always stick near the shoreline when swimming, using the cover of logs and rocks to avoid predation.
10 years is the maximum limit for most subspecies.
Aquatic insects are the main source of food for freshwater cutthroats, though fish that live along the coast will eat salmon eggs if possible. Marine cutthroats have more options available, ranging from small fish like juvenile pink and coho salmon, to herring and small crustaceans such as crab.
Generally takes place in late winter/early spring. Saltwater cutthroats spawn in the same way as steelhead and other salmon species, as they swim upstream into freshwater and females deposit eggs in gravel. Cutthroats are repeat spawners, but still have a fairly high post-spawning mortality rate due to weight loss.A female cutthroat produces 1,100-1,700 eggs on average, going as as 4,500 for bigger fish.
Like most species of fish, cutthroats return to their river of origin to spawn. Adults begin the swim upstream in the fall, but actual spawning doesn't take place until several months later. If the fish survive the process, they return to saltwater.
For freshwater species, other trout like rainbow and brown pose the biggest threat, but birds such as blue herons and kingfishers are also a threat. For marine cutthroats, harbor seals, spiny dogfish, and adult salmon are the top predators to look out for.
Information courtesy of the U.S. Geological Survey.