BIOLOGY OF THE ROUGH SCAD TRACHURUS-LATHAMI, ON THE SOUTHEASTERN COAST OF BRAZIL

This paper presents the current state of knowledge of Trachurus latham i on the southeastern coast of Brazil. In relation to its early life h istory, most of the studies are concentrated on morphological developm ent, seasonal occurrence, distribution and abundance of larvae. The eg g stage has not yet been studied. Ichthyoplankton surveys showed that rough scad is the dominant species among carangids and its stock seems to be stable. Results of the Dec/91 cruise demonstrated an increase o f its population reinforcing the suggestion that the rough scad may be an alternative to the declining sardine fishery. Morphological studie s of adult T.lathami revealed no distinct populations within this area . Comparing its distribution and abundance with those found in the lit erature, the existence of another population in the south of Brazil, U ruguay and Argentina has been discussed. The first maturity occurs at about 115 mm total length (two years-old). Spawning activities are mor e intensive in early spring and summer, but extend all year-round acco rding to ichthyoplankton surveys. Age determination was made by readin g annuli on otoliths. The maximum number of annuli was 8. Von Bertalan ffy growth parameters were L(infinity) = 259 mm TL, K = 0.16 year(-1 a )nd t(0) = -1.85. The population structure in terms of age and length composition is given. Its feeding behavior, as well as the association levels with other marine pelagic species, are presented.