Complex sentence: The Yellowstone cutthroat trout is a prized game fish, with fly fishing the most popular angling method, since the subspecies feeds primarily on insects as adults, unlike introduced brown trout which are more piscivorous.
Split into simpler sentences: The Yellowstone cutthroat trout is a prized game fish. Fly fishing is the most popular angling method, since the subspecies feeds primarily on insects as adults, unlike introduced brown trout which are more piscivorous.