|Family overview: The one bowfin species that exists today, Amia calva, is all that remains of a large group of marine and freshwater fishes that thrived about 150 million years ago. A “living fossil,” the bowfin shows some body features, such as a lunglike swim bladder, which are typical of primitive fish, and other characteristics, like smooth scales, which are found in the more highly evolved soft-rayed fishes.
Bowfins are widely distributed over the eastern half of North America. In Pennsylvania, they are found in Presque Isle Bay, on Lake Erie, and in a few other scattered locations in the Delaware, Ohio and Susquehanna River watersheds. Their preferred habitat is heavily vegetated lakes, sluggish rivers and swamps. Bowfins can tolerate very warm water. Their body functions become limited and their activity slows when it becomes too hot. To overcome these adverse conditions, the bowfin has a swim bladder that opens to the throat. The bowfin, like the gar, can go to the surface, stick its head out, and gulp air. Bowfins have also been called “dogfish” and “mudfish.”
Identification: Bowfins are robust-looking fish. The body is covered with heavy scales and the head is covered with bony plates. Their color is olive-green on the back, lighter and mottled on the sides, and yellowish on the belly. A single long, low dorsal fin extends over half the length of the body. It is light with lengthwise stripes. The dorsal fin is just barely separated from the broadly rounded tail fin, which shows curving stripes. A pair of short barbels protrudes near the nostrils. The mouth is filled with sharp, strong teeth. Male bowfins can be identified by the dark spot on the upper side of the base of the tail fin. This spot is ringed with bright-orange or yellow-green during the breeding season. This spot may represent a false eye that could direct predators to the bowfin’s tail, instead of the head, thus providing it with an escape mechanism. Bowfins grow to several feet long and nearly 10 pounds.
Life history: Bowfins spawn in the spring. The male uses his fins to clear a round depression in the weedy shallows, into which the eggs of several females are deposited. The adhesive eggs fall on the vegetation and remain until they hatch, in about eight to 10 days, while the male guards them. The male also watches over the young fry. An average-sized female bowfin, of about four or five pounds, produces 23,000 to 64,000 eggs.
Bowfins are ready to spawn when they are two to four years old. The males then are about 18 inches long and the females are about two feet long. Their lifespan in the wild is about 10 years.
Bowfins are predators, eating mainly fish, but also taking crayfish, frogs, mollusks and aquatic insects. When compared to other fish, the bowfin’s actions are sluggish, but with its size and feeding habits, it may strike an angler’s artificial lure or live bait. As a Pennsylvania candidate species, bowfins must be released immediately unharmed.