© 1997 by ICES/CIEM International Council for the Exploration of the Sea/Conseil International pour l'Exploration de la Mer
Reproductive biology of scad, Trachurus mediterraneus (Teleostei, Carangidae), from the Gulf of Trieste
Institut de Zoologie, Université de Fribourg Pérolles, CH-1700, Fribourg, Switzerland
Dipartimento di Biologia, Université di Trieste Via L. Giorgieri 7, I-34127, Trieste, Italy
A histological study of gonads and a statistical analysis of biometric variables were used to study the biology of scad, Trachurus mediterraneus. The reproductive cycle was subdivided into three phases: a pre-reproductive phase from January to April, a reproductive phase from May to August and a post-reproductive phase from September to December. Five sexual maturity stages could be described in both males and females. The gonosomatic index reached its maximum value in JuneJuly. In both sexes size and age at sexual maturity averaged 16 cm and 2 years, respectively. At the end of the reproductive period, gonadal regression was observed first in females. The analysis of the lengthweight relationship showed conditions of positive allometry in MayJune, negative allometry in July and October, and isometry in the other months.
Keywords: Trachurus, reproduction, gonadal stages, allometryisometry
Received 15 February 1996; accepted 17 June 1996.