ABSTRACT. Stages of gonadal development in females of "barba-ruça" shrimp (Artemesia longinarisDecapoda, Penaeidae). The stages of gonadal development for the female of "barba-ruça" shrimp (Artemesia longinaris Bate, 1888) were characterized based on histological analysis. Four stages (immature, almost mature, ripe and spawned) were determined according to the structure and arrangement of cells in the ovary. Each stage corresponds macroscopically to a characteristic color, except stages I (immature) and IV (spawned), in which colors are very similar and can be distinguished only microscopically. The chromatic scale varies from white/translucent (stage I), neutral green (almost mature) to dark green (ripe). The mean size of cells was 56.9 µm (±3.5) (stage I), 127 µm (±2.6) (stage II) and 183 µm (±1.91) (stage III). The size frequency of cells was polimodal, and different cell stages were observed in ripe ovary, suggesting the occurrence of multiple spawning. The chromatic scale developed is an important tool for laboratory analysis, and can be easily used to identify the gonadal stages.
Population connectivity in the blue crab Callinectes sapidus was evaluated along 740 km of the Western South Atlantic coast. Blue crabs are the most exploited portunid in Brazil. Despite their economic importance, few studies report their ecology or population structure. Here we sampled four estuarine areas in southern Brazil during winter 2013 and summer 2014 in order to evaluate diversity, gene flow and structure of these populations. Nine microsatellite markers were evaluated for 213 adult crabs, with identification of seven polymorphic loci and 183 alleles. Pairwise FST values indicated low population structure ranging from -0.00023 to 0.01755. A Mantel test revealed that the geographic distance does not influence genetic (r = -0.48), and structure/migration rates confirmed this, showing that even the populations located at the opposite extremities of our covered region presented low FST and exchanged migrants. These findings show that there is a significant amount of gene flow between blue crab populations in South Brazil, likely influenced by local current dynamics that allow the transport of a high number of larvae between estuaries. Considering the elevated gene flow, the populations can be considered a single genetic stock. However, further information on population size and dynamics, as well as fishery demands and impacts at different regions, are necessary for harvest management purposes.
The stages of gonadal development for the female of white shrimp (Litopenaeus schmitti (Burkenroad, 1936)) were characterized based on histological analysis. Four stages (immature, developing, ripe and spawned) were determined according to the structure and arrangement of cells in the ovary. Each stage corresponds macroscopically to a characteristic color, except stages I (immature) and IV (spawned), in which colors are very similar and can be distinguished only microscopically. The chromatic scale varies from white/translucent (stage I), gray/green (developing), dark green to black (ripe). The mean size of cells was 54.01 µm (±3.5) (stage I), 136.80 µm (±8.8) (stage II) and 199.80 µm (±6.4) (stage III). The size frequency of cells was polymodal, and different cell stages were observed in ripe ovary, suggesting the occurrence of multiple spawning. The smallest ripe female measured 146 mm and the largest 180 mm of the total length. Estimated mean length at first maturity was 152 mm and the length at which 100% of females are mature is 170 mm.
KEY WORDS:Litopenaeus schmitti, shrimp, reproduction, gonadal histology, length at first maturity RESUMO Os estágios de desenvolvimento das gônadas das fêmeas do camarão-branco (Litopenaeus schmitti (Burkenroad,1936)) foram caracterizadas por análise histológica. Quatro estágios (imaturo, em desenvolvimento, maduro e desovado) foram determinados de acordo a estrutura e arranjo das células no ovário. Cada estágio corresponde, microscopicamente, a uma cor característica, exceto nos estágios I (imaturo) e IV (desovado) nos quais as cores são muito similares e podem ser distinguidas apenas histologicamente. A escala cromática varia do branco/translúcido (estágio I), cinza/verde (em desenvolvimento), verde escuro a preto (maduro). O tamanho médio das células foi 54,01 µm (±3,5) (estagio I), 136,80 µm (±8,8) (estágio II) e 199,80 µm (±6,4) (estágio III). A distribuição de frequência do tamanho das células foi polimodal, e diferentes estágios celulares foram observados nos ovários maduros, sugerindo a ocorrência de desovas múltiplas. A menor fêmea madura mediu 152 mm e o comprimento em que 100% das fêmeas estavam maduras foi 170 mm.
-This study was conducted in two estuarine inlets (Saco da Mangueira and Saco do Arraial) at the Patos Lagoon estuary, southern Brazil. The changes in relative abundance and size of post-larvae and juvenile shrimp Farfantepenaeus paulensis and juvenile blue crab Callinectes sapidus were compared, considering the influence of salinity and the presence of submerged seagrass meadows. The analyses were performed using generalized linear models (GLM) for abundance variations and ANOVA for variations on the size of individuals. The pink shrimp was more abundant at Saco da Mangueira, in seagrass meadows and areas of higher salinity. The blue crab was more abundant at Saco do Arraial and in lower levels of salinity. The importance of submerged vegetation for the blue crab lies in a preference of smaller crabs of the species for the seagrass meadows. It has been shown that these species choose different habitats in the estuary, and both the salinity and the presence of submerged seagrass meadows influence the selection of habitat.
One of the most problematic fishing methods in terms of by-catch and discarding is prawn-trawling. This paper analyses the incidental catch of an artisanal trawl fleet during two discrete Artemesia longinaris fishery seasons (2002 and 2004). The fishery season of A. longinaris operates monthly and it takes place in the surrounding area of the Barra do Rio Grande. Sampling was carried out during the fishing season (April–December) always on the same artisanal trawl boat. An observer was included on-board to avoid loss of information due to discards made by the fishermen at sea. Fifty species were caught: 38 fish and 12 crustaceans. Discrete fauna abundance and composition were recorded in analysed years, with higher by-catch ratios associated with elevated rainfall and low salinity. The overall discard ratio was 1:5.6, with values ranging from 1:11.3 in 2002 to 1:2.5 in 2004. The most striking differences between both years analysed were observed during autumn (1:75 in 2002 and 1:11.30 in 2004) and winter (1:16 in 2002 and 1:0.97 in 2004), while spring presented similar values (1:8 in 2002 and 1:4 in 2004). The discard ratio estimated in terms of number showed a different pattern, presenting overall values of 1:2.24 in 2002 and 1:0.5 in 2004. Higher estuarine runoff may have increased biomass production in the surrounding area of Patos Lagoon during 2002, sustaining higher abundance of estuarine-related and marine species in the area, as well as higher mean trophic level and abundance of top-predators. Conversely, A. longinaris production was consistently lower, since this marine species does not tolerate marked reductions in salinity. In 2004, salinity was higher, associated with low rainfall and favouring A. longinaris abundance in the area. During this dry year, the target-species was dominant in samples resulting in very low by-catch ratios, especially in winter (1:0.97). The catch was mainly composed of juvenile fish, since fishery is performed in nursery grounds.
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