Abstract
One population of the grey mullet mugil cephalus inhabits the waters around the Taiwan Strait and in the spawning season migrates to the coasts of southern Taiwan. The grey mullet is long-lived and produces a great number of small, nonbuoyant eggs. The female grows larger in size and shows high GSIs than the male. Lee's phenomenon is marked in the grey mullet. These characteristics of grey mullet correspond well to its relatively stable pattern of fluctuation in numbers. None of the fish species examined by one of the authors, Kawasaki, shows such characteristics, which is interesting from the viewpoint of evolutionary ecology.
