ABSTRACT

ABSTRACT. REPRODUCTIVE BIOLOGY OF OUGOSARCUS JENYNSII (GÜNTHER) (CHARAClFORMES, CHARAClDAE) FROM CUSTÓDIAS LAGOON, TRAMANDAÍ, RIO GRANDE DO SUL, BRAzrL . The Custódias lagoon has a great importance in the Tramandaí system, because it works as reproduction area, feeding alld nursery grounds to several fish species. The aim of this work is the study of aspects related to the reproduction of Oligosarcus jenynsii (Günther, 1864) as such as reproductive period, sexual ratio, fecundity and size of the first gonadal maturation. The specimens were sampled monthly from Octoberl1994 to Octoberl1995. FOI' each sex, maturation curves were established, based on the monthly variation oflhe gonadossomatic index mean values, as well as, lhe relative frequencies ofthe sexual malurity slages. Breeding seasons look place during lhe winler and spring. The sex ratio was significanlhly differenl from I: I, with more females than male in almost all month. The species had a average fecundity of 9.694 ovocyles. The estimated size of first sexual maluration was 114 nun for male and 131 mm for females. KEY WORDS. CharacifOlmes, Oligosarcusjenynsii, fecundity, reproduction A lagoa das Custódias, que faz parte do Sistema Lagunar de Tramandaí, Rio Grande do Sul, caracteriza-se por apresentar uma ictiofauna constituída por representantes tanto de água doce, como marinha. Sendo assim, é de grande importância para os peixes costeiros, pois serve como área de reprodução, criadouro natural e alimentação, constituindo-se em um local para manutenção e proteção temporal do ciclo de muitas espécies.Oligosarcus jenynsii (Günther, 1864), popularmente conhecida como tambicu, branca ou peixe-cachorro, é uma das espécies mais constantes e abundantes nas lagoas costeiras do litoral norte do Rio Grande do Sul. A espécie tem como distribuição geográfica os arroios, rios e lagoas da região costeira e da planície interior do Rio Grande do Sul estendendo-se, também, pelos territórios do Uruguai e Argentina (MENEZES 1987).

ABSTRACT. The aim of this study was to analyse the reproductive period, fecundity and the size of the first gonadal maturation of Cyphocharax voga (Hensel, 1869) of Cust6dias Lagoon, state of Rio Grande do SuI, Brazil. The specimens (293 males and 247 females) were collected monthly, during the period between October 1994 and September 1995. The reproductive period took place from early winter until the end of spring. The average absolute fecundity was 36608 oocytes. The size of the first gonadal maturation was estimated in 121 and 128 mm for males and females respectively.