Ecologia alimentar e reprodutiva da piaba-do-rabo-amarelo, Astyanax cf. lacustris (Reinhardt, 1874) (Osteichthyes: Characidae) na Lagoa do Piató, Assu, Rio Grande do Norte, Brasil

The feeding habits and biological aspects of the reproductive cycle of two-spot astyanax, Astyanax cf. lacustris (Reinhardt, 1874) were investigated. Fish samples were captured on a monthly basis, using gillnets of 4 cm mesh size, from the Piató Lake, Assu, Rio Grande do Norte, during the period of September, 2006 to August, 2007. Physico-chemical parameters, such as, temperature, electrical conductivity and dissolved oxygen of the lake were registered. The monthly values of rainfall also were obtained. The 360 individuals captured, were measured, weighed, dissected, and stomach weight and the stage of gonadal maturity were registered. The stomach contents analyses were carried out based on volumetric method, points, frequency of occurrence and applying the Index of Relative Importance. The degrees of repletion of the stomachs were determined besides the Index of Repletion relating to feeding activity variations and frequency of ingestion with limnological parameters and rainfall. The food items identified were separated into distinct groups according to their origin. Sex ratio and Gonadosomatic Relation of females were verified to determine the spawning period and fecundity. The physico-chemical parameters presented the following annual mean values: temperature = 28.8ºC, electrical conductivity = 992.5 µS.cm-1; dissolved oxygen = 4.9 mg.L-1 during the study period. The annual mean of the rainfall was 63.5 mm. The results indicate that this species present an omnivorous feeding habit with a tendency towards insectivory, with an increase in feeding activity during the dry season. The aquatic oxygen to interfere very importance in the feeding activity than the others factors physico-chemicals of water and rainfall. There was a predominance of females, with a sex proportion of 1M:7F. The macroscopic characteristics of the ovaries and testicles revealed four stages of gonadal development: immature, maturing, mature and spent. A temporal variation was observed for the gonadal development of males and females. There was reproductive activity through out the year, with peaks in the months of February, April and June to correspond with the rain of precipitation of the region. The mean fecundity was 7.681 mature oocytes, varying from 4.476 to 12.036, with mean of 7.681. There was positive relation between fecundity and body mass. Condition Factor is not an efficient indicator of the reproductive period of this species. The species A. cf. lacustris is an opportunist and is well adapted to the conditions of the semi-arid Caatinga Biome

Estrutura populacional e aspectos reprodutivos do Octopus insularis Cephalopodas: Octopodidae: implicações para o manejo da pesca de polvo no município de Rio de Fogo-RN

In northeastern Brazil, Octopus insularis is the most commercially important cephalopod species and its capture has been performed for several years by the lobster fishermen in the region. In order to obtain information about the reproductive biology, 1108 specimens were collected between November 2009 and September 2011 in the landings and fish markets of Rio do Fogo (RN). For each specimen the mantle length (CM) and total fresh weight (PT) were recorded. Gonads of 264 males and 295 females were examined macroscopically and histologically to assess sexual maturation and determine reproductive indices. Four reproductive stages were determined for males (immature, maturing, mature and post-mature) and females (immature, early maturing, late maturing and mature). The average of eggs recorded in the female s gonads was 93.820 and 39 was the average of spermatophores found in male Needham s complex. Spermathecae with sperm were found in females with 69 mm CM (immature). Males and females become sexually mature at 64.41 and 98.50 mm of CM, respectively. The weight at sexual maturity was 270 g for males and 630 g for females. The values of the size and weight at sexual maturity found in this study show that males mature at smaller sizes than females. For both sexes the maturation peaks occurred in February and November 2010 and also in September 2011. The periods of maximum reproductive activity lasted about 3 months and it seems to occur every 7 10 months. Only one spent female (stage V) was found and the number of mature females was low. Presumably, mature females migrate to deep waters with complex habitat to protect the offspring, indicating that fishery by snorkeling with maximum depth of 15 meters is not reaches this part of the stock. Finally, it is noticeable the importance of the establishment of management strategies for the exploitation of O. insularis different of the ones used for O. vulgaris, once the species have distinct biological features

Dinâmica reprodutiva e parasitária de quatro espécies de peixes das águas costeiras do Sudoeste do Oceano Atlântico, Brasil

The present study investigated the reproductive dynamics and parasitism of four species of marine fishes: serra Spanish mackerel, Scomberomorus brasiliensis, Atlantic leatherjacks, Oligoplites saurus and O. palometa,, and Atlantic bumper, C. chrysurus, during the period of August, 2005 to July, 2007, in the coastal waters of Southwest Atlantic Ocean, Brazil. The collected fish samples were measured, weighed, dissected, the gonads were weighed and examined to separate the sex. The gonadosomatic index (GSI), fecundity, type of spawning, the breeding season, the macro and microscopic characterization of the gonads were determined. The ectoparasites from the branchial chambers and bucal cavity of the fish were collected, measured, weighed and identified. The sex ratio of the study fish species were approximately 1M:1F, however, there was a predominance of males of O. palometa (3M:2F). The GSI of fishes varied according to their reproductive cycle and the stage of gonadal maturation. The highest values of GSI and the spawning period coincided with the rainy period of the region. The females presented total spawning and the fecundity was positively correlated with the weight of the ovary and the body. Four stages of development of the gonads immature, maturing, mature and spent were identified macroscopically and histological analyses of ovaries revealed the different phases of oocyte development. Three species of isopod parasites were identified in the study fishes: Livoneca redmmanni, Rocinela signata and Cimothoa spinipalpa. The first two species occurred in the branchial cavities of C. chrysurus and S. brasiliensis. The isopod C.spinipalpa (a new species) was registered for the first time in the bucal cavity of O. saurus and O. palometa. The parasitic isopods preferred the branchial chambers and the bucal cavity of the host fishes as these were protected microhabitats. The isopods parasitized the immature, maturing and mature fishes. The prevalence of infection of isopods in the hosts varied from 16 to 21%, though in O. palometa it was 60%. In the rainy period the highest isopod parasitic occurrence was registered, however, this did not prejudice the normal reproductive cycle of the host fish.