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The purpose of this study was to determine the distribution and size of natural stocks of the mussels Mytella guyanensis (Lamarck, 1819) and M. falcata (d'Orbigny, 1846) in the Cananéia-Iguape-Ilha Comprida lagoon estuarine system. Samples of mussels and related information were collected in four areas distributed along Cubatão Sea (I), Trapandé Bay (II), Ararapira Channel (III) and Cananéia Sea (IV) from June 2004 to June 2005. Each area was subdivided in plots that represented the mussels natural banks. The total area occupied by the mussels was estimated. From each one of the 48 delimited plots, 120 samples were collected along 2 transects, summing up 5.760 samples. The animals were counted, measured for length and weight. It was impossible to estimate the stock of M. falcata, due the very low number of individuals. The data presented are from M. guyanensis. The bivalves' density (nº/m²) ranged from 0.64 to 188.35, showing a heterogeneous distribution among plots. The total area occupied by the bivalves was 438.824 m², with an estimated population of 18.646.453 mussels. Within this population 44.5 % were of commercial size (> 40 mm). The maximum length observed was 72 mm. The most appropriate sites for mussel extraction are located in Cubatão Sea (I) and Cananéia Sea (IV) as these had higher biomass and greater numbers of individuals of commercial size. The results of this research shall contribute to a rational extraction policy.

This study presents the first record of an alien species of oyster in Bertioga, São Paulo State (Southeastern Brazilian coast). Alien oysters were found attached to mangrove roots, rock shores, stones and gravel in the riverbed, forming clusters of 10–20 individuals and cohabiting with native oyster species (Crassostrea mangle, C. brasiliana and Ostrea sp.). Results are presented based on molecular analysis of specimens collected in the Itaguaré River in June 2014. We used partial sequences of 16S and COI genes to assess the taxonomic identity. The Neighbor-joining method was used to analyze phenetic relationships among samples and the genetic diversity was calculated from the Kimura two-parameter (K2P) distances. The sequences in this work clustered with a sequence of “Saccostrea cucullata” from Madagascar for both genes (COI and 16S) and presented a genetic distance of 1.7–2.2% and 3.5–5.3% from other sequences of “S. cucullata group” for 16S and COI fragments respectively. The genetic distances from others Saccostrea species (S. palmula, S. glomerata and S. mordax) ranged from 4.7 to 9.1% for 16S and from 13.8 to 19.0% for COI. The genetic distances from other oysters’ species sequences (genera Ostrea and Crassostrea) are over than 14.0% and 25.0% for 16S and COI respectively. The record is discussed in the context of possible consequences on the environment and probable pathways of introduction. This is the first published record of a Saccostrea species in the southwestern Atlantic Ocean.

The capture of live bait for sport fishing is an important activity for fishing communities. The main species used for this purpose are members of the genus Gymnotus, which comprises numerous species of cryptic nature that are difficult to identify based on external morphology. The aims of this work were to identify through partial sequences of the COI gene Gymnotus species fished in the Jacaré-Guaçu River, SP, and to develop a molecular diagnostic approach using PCR-RFLP to identify these species. Partial COI sequences were compared to those of other species deposited in GenBank. The sequences were assessed in the NEBCutter program to determine restriction sites in the sequence and the enzymes to be tested. Phenetic analysis performed by Neighbor-Joining method showed that the specimens sampled belong to two species preliminary identified here as G. cf. sylvius and G. cf. cuia, with G. cf. sylvius accounting for 95.2% of the individuals sampled. The enzymes NlaIII and SacI generated fragments that allowed distinguishing the Gymnotus species using PCR-RFLP. This analysis can be used to accurately identify these species, which is fundamental for monitoring Gymnotus fishing and assessing the conservation of this genetic resource.

The aim of this study was to analyze economically the production of scallops Nodipecten nodosus at the north coast of São Paulo State, from a hypothetical cultured area of 0.2 ha. We used a final density of 16 scallops floor-1 of Japanese lanterns and considered a survival rate of 68.85% and 81.22% at the final cycle of nine months. In these conditions, the intern rate of return (IRR) ranged from 40.58% a 103.99%, based in commercial selling prices of R$ 39.50 and R$ 49.50-1 per dozen for the two survival rates. The total production cost (TPC) per dozen of scallops varied from R$ 24.27 to R$ 28.63, lower than the considered selling prices. The highest net present value (NPV) obtained was R$ 989,376.35 for the selling price of R$ 49.50 and survival of 81.22% and the lowest NPV was R$ 288,209.84 for the selling price of R$ 39.50 and survival of 68.85%. These results show the economic viability of the scallop’s culture, fact that may promote the development and expansion of this activity in north coast of São Paulo State.

Oysters of the genus Crassostrea are an economically important resource occurring along the Brazilian coast, mainly in estuarine regions. Inter-and intra-population genetic diversity is essential for monitoring long-term genetic changes and for sustainable use of this bivalve by coastal fishing communities. Microsatellite markers were used to evaluate the genetic diversity of natural populations of the mangrove oyster Crassostrea rhizophorae in southeastern Brazil. Samples of 150 oysters from four areas were analyzed. Microsatellite loci were obtained from an enriched microsatellite library. The genetic structure was evaluated using an index of genetic differentiation described previously. The effective population size and rate of gene flow were estimated through a maximum likelihood coalescent approach using Migrate. The mean number of alleles ranged from 10 to 21 and the expected heterozygosity from 0.89 to 0.91. Evidence of a possible bottleneck effect under three mutational models was found. The D est index indicated low to moderate differentiation among sample locales. Coalescent analysis showed variation in effective population size and asymmetry in the gene flow among samples. Levels of genetic variability and differentiation found among C. rhizophorae populated banks have important implications for the sustainable harvest, cultivation and conservation of this marine resource in the studied area.

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