Reprodução do camarão sete-barbas Xiphopenaeus kroyeri (Heller 1862): uma nova abordagem para estudos do desenvolvimento ovariano de camarões peneídeos

Abstract

The morphological changes during ovarian development of Xiphopenaus kroyeri were evaluated in order to establish a model to better understanding their reproductive dynamics. A total of 1,289 females of Xiphopenaus kroyeri were collected through artisanal fisheries were collected from artisanal fisheries in Lucena, Paraíba, Brazil. Females were investigated in relation to different reproductive aspects: in chapter 1, the oogenesis was classified into six distinct phases: chromatin nucleolar oocytes, chromatin perinucleolar oocytes, oocytes in primary vitellogenesis, oocytes in secondary vitellogenesis, mature oocytes, and atretic oocytes. Histochemical observations suggested a progressive increase of the proteins and neutral polysaccharides in vitellogenic oocytes until their final maturation stage. Follicular cells composed the follicular complex forming an external epithelium in vitellogenic oocytes, and are probably involved in protein transfer during ovarian maturation process. Collagen and glycoprotein vesicles were also identified in the cytoplasm of mature oocytes. In chapter II, two methods of macroscopic analysis of the ovaries were tested for accuracy in establishing maturation stages compared to histological analysis, as well as possible implications in determining the spawning season. One method evaluated the maturation stage was assessed by observing the ovary through the exoskeleton with the help of artificial light, while the other was evaluated macroscopically from the extraction of the fresh ovary, morphology and appearance of the tissue lining the ovary. The second method showed greater agreement with the histological analysis than the first method, emphasizing the importance of observing the morphological characteristics of a freshly caught female, since the staining of the ovaries tends to ovary over time. Both methods were efficient in identifying the ripe stage, suggesting that both can be used in the management of captive broodstock. The grouping of the spent and resting stages into a single stage can be considered a major problem, because they present characteristics and opposite interpretations from the histological point of view, resulting in serious problems in the estimates of spawning season. In chapter 3, we identified six stages of ovarian development, based on macroscopic and histological analysis: immature, early developing, advanced developing, ripe, spent, and resting. The spent and resting stages, which have been grouped in reproductive studies of penaeids shrimp, were separated for the first time. We observed vesicles accumulated in the cytoplasm of ripe cells. The histological analysis showed oocytes with synchronous development presenting total spawning. The mean length at maturity (CL50) for females was 1.3 cm CL. The reproductive cycle was classified as seasonal for females, with greater ovarian maturity and gonadosomatic index from October to March. The spawning peak occurs during the period of highest rainfall, with a higher percentage of spent females. Taken together, the present findings contribute to the current knowledge on the ovarian morphology, maturation process of penaeids, supporting future studies on reproductive biology which may be useful for sustainable management of commercial penaeid fisheries and reproductive performance of Xiphopenaeus kroyeri in captivity.