The estuary as a habitat for spotted seatrout, Cynoscion nebulosus.

The spotted seatrout is one of the most valuable fish of the southeastern United States. It is one of the few species that depends on the changeable habitats of estuaries and lagoons, even spawning there. Both young and adults are tolerant of the normal environmental extremes of estuaries, which are too rigorous for most marine fishes. This enables the spotted seatrout to reproduce, and grow almost unhindered by predation and competition. Spotted seatrout populations of more northern estuaries apparently make seaward movements to escape winter cold but southern populations do not exhibit a strong offshore movement. They are nearly nonmigratory in Florida; tagging studies show that they seldom move more than 30 miles from the point of tagging. Since most of the favored estuarine areas are separated by long stretches of exposed seashore there is little exchange of stocks between estuary systems. The nonmigratory character of the species, when combined with differences in habitat, has resulted in spotted seatrout populations having different growth rates. Unfavorable conditions for feeding or spawning in any given estuary, which cause declines in abundance, are likely to be felt for long periods since the region will not likely receive large numbers of immigrants from other estuaries.