Except for the rare abnormal specimen, two of the
four flatfish families (tongue soles and turbots) are always sinistral
(eyes on the left side); the other two (both flounders) are dextral
(eyes on the right side).
Yes, larvae and juveniles of the shad and the
striped bass were taken from the Atlantic and released in the
Pacific in the 1870's. So successful were the transplants that shad
became permanent inhabitants of waters from southeast Alaska to Los
Angeles, and striped bass support a good sport fishery off the
California and Oregon coast.
All four species reach from seven to ten feet in length.
Because of their tremendous weight, the fish are difficult to land and
weigh. One accurately weighed specimen tipped the scales at 3,102
One not native to an area, but introduced either by
accident or design. Some such species can cause problems. Often their
natural predators are absent from the new area, permitting more rapid
reproduction rates than those of natural inhabitants, sometimes at the
expense of more desirable native fish. The "walking catfish" in
Florida is an example. Thought to have escaped from a private
aquarium, the catfish have shown a remarkable ability to avoid
eradication efforts by man. An aggressive and voracious fish, it poses
a threat to other forms of aquatic life. Population is now estimated
in the millions.
Flounder images courtesy of "Regulatory Fish Encyclopedia, Office of Seafood and Office of Regulatory Affairs, Food and Drug Administration, 1993-1996."