Distribuição e estratégia reprodutiva de duas espécies de bagres (Siluriformes, Ariidae) em um estuário do Sudeste do Brasil, Atlântico Oeste Tropical

• Autor(a) principal: Sciarretta, Thais do Rego
• Data de Publicação: 2016
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Institucional da Universidade Federal do Espírito Santo (riUfes)
• Texto Completo: http://repositorio.ufes.br/handle/10/8277
• topic: Catfish; Reproduction; Estuary; Bagre-urutu; Bagre-amerelo; Ecologia; Estuários; Biogeografia; Bagre (Peixe) x Reprodução; Pesca artesanal; Conceição da Barra (ES); 502

Estuarine ecosystems represent unique environments of paramount importance for breeding and development of several species, such as, the marine catfishes of the Family Ariidae. These fishes attract great interest due to their abundance and importance in the food chain. This study aimed to describe the distribution and reproductive strategy of the catfishes Genidens genidens and Cathorops spixii in Conceição da Barra’s APA. Samples were collected monthly between August 2014 and July 2015 at neap tides, using an otter trawl net with doors in four areas along estuarine salinity gradient. Abiotic variables were also collected (salinity, temperature, dissolved oxygen and turbidity). Through macroscopic analysis and corroboration with histological slides of gonads, the sex, reproductive period, spawning season and size at first maturity (L50) were determined. We estimated the absolute fecundity and the relationship between the total number of eggs and larvae in the oropharyngeal cavity (NEL) and the total length (TL) of incubators specimens, in addition, we associated the environmental variables that influenced the distribution of species. We collected 1569 specimens of G. genidens and 2180 specimens of C. spixii. There was no significant difference in the overall sex ratio of both species. The L50 for females and males of G. genidens and C. spixii were 163 mm and 161mm; and 145 mm and 146 mm, respectively. The reproductive period was based on the presence of ovaries in the "capable of spawning" and "hydrated" stages, the highest values of IGS and ΔK, occurring from September to December for both species. G. genidens presented a longer period of spawning occurring between of October and February, while C. spixii from December to February. The two species demonstrated weak linear relationship between NEL and TL. The absolute fecundity ranged from 7 to 28 oocytes, with a strong linear relationship with TL for G. genidens, while C. spixii ranged from 17 to 44 oocytes, showing weak linear relationships. The environmental variables that positively affected the distribution of G. genidens were depth and turbidity, and negatively was salinity. For C. spixii were temperature, turbidity and deph, and negatively was salinity. Juvenile G. genidens were mape abundant in the lower area of the estuary; sub-adults in the lower and middle portion and adults in the middle portion. Juveniles of C. spixii showed higher densities in the lower area and middle of theestuary; sub-adults in the outer portion and adults in the lower and middle portion,showing that these species use this environment in different ways. In Brazil, protection regulations for the catfishes of the family Ariidae were set out in the Decree Nº. 42 of 18/10/84, by SUDEPE, which establishes the closed season in the states of RS, SC, PR and SP, between January 1st and March 31st . We suggest the implementation of a closed season in the state of ES and a revaluation of this period, to include the incubation period, the periods of final maturation of the gonads, which take place from November to February.