Life History and Ecology of Sand Seatrout Cynoscion arenarius Ginsburg, in the Northern Gulf of Mexico: A Review

Abstract

Sand seatrout usually represent from 5-7% of trawl catches by weight, 8-10% by number, and consistently rank among the top 5 most abundant species in demersal surveys. Sand seatrout mature at 140-180 mm TL, begin to enter the late developing, gravid, or ripe stages around 180 mm TL, and first spawn at 12 months. Spawning occurs primarily from March through September with distinct peaks in both March-April and August-September. Spawning initially takes place in midshelf to offshore waters and moves shoreward as the season progresses, with most occuring in the lower estuary and shallow GOMEX (7-15 m water depth). Larvae are primarily collected in water depths of <25m, more are collected at night than during the day, and they are somewhat surface-oriented but become increasingly demersal with size. In pass studies, larval sand seatrout are also more abundant on night flood tides than at other times. Larvae migrate into shallow areas of the estuary where they remain until at least 50-60 mm TL after which they move to deeper water. Mean size predicted by regression was 250, 425, and 573 mm TL at ages I, II, and Ill, with a typical lifespan of 1-2 years and possibly up to 3 years. Total annual mortality approaches 100% based on trawl data if the lifespan is one year and 90% if two years. Distribution of sand seatrout appears restricted more by water temperature than salinity. Electrophoretic evidence is unclear whether sand seatrout should be recognized as distinct from weakfish. Evidence provided by otolith aging of larvae and differences in larval pigmentation, however, supports the separation of two co-occurring morphological types and suggests separate populations of sand seatrout in the northern Gulf of Mexico.