Modulating factors of the abundance and distribution of Achelous spinimanus (Latreille, 1819) (Decapoda, Portunoidea), a fishery resource, in Southeastern Brazil.

This is the first study to examine how different environmental factors may influence the distribution of swimming crab Achelous spinimanus across geographically distant and distinct habitats. We analyzed the influence of bottom water temperature and salinity, sediment texture and organic matter content on the spatiotemporal distribution of A. spinimanus. The crabs were collected from January 1998 until December 1999 by trawling with a shrimp fishing boat outfitted with double-rig nets. The sampling took place in Ubatumirim (UBM), Ubatuba (UBA) and Mar Virado (MV) bays, located in the northern coast of São Paulo State (Brazil). These three bays were chosen as they differed in many physiographic features. We captured 1,911 crabs (UBM = 351; UBA = 1,509; MV = 51), and there were significant differences in abundance between bays and between stations. The distribution of A. spinimanus was primarily associated with sediment features: abundance was higher in stations with sandy sediments classified as gravel, very coarse sand, and intermediate sand. Portunoidea usually burrow in the sediment for protection against predators and to facilitate the capture of fast prey. In addition, the station with the highest abundance of A. spinimanus was also naturally protected from fishing activities, and composed of heterogeneous sediment, in terms of grain size. Hence, the combination of a favorable sediment heterogeneity and protection from fishery activities seemed to be effective modulators of the abundance and distribution of A. spinimanus in these bays.

Age and growth of the white croaker Micropogonias furnieri (Perciformes: Sciaenidae) in a coastal area of Southeastern Brazilian Bight

Studies on age and growth of fish populations have direct application in fisheries and contribute for policies of conservation. Our aim was update information on the Micropogonias furnieri growth parameters based on sagittae otoliths annulis readings, and we expected that the studied population from Southeast Brazil can reach more longevity than the reported in the available literature. We examined 286 individuals between August-2010 and July-2011 from Ubatuba Bay, SP. The Total Length ranged 200-480 mm. The determined growth parameters were: Males, L∞ =523.4mm, k = 0.05×year-1, t0 = -8.78 year; Females L∞ = 573.5mm, k = 0.06 × year-1, t0 = -7.49 year. The MI and % of edge type evidenced the formation of one ring per year during autumn/winter, coinciding with low temperature and low growth rate. These results differed from those reported for the Vazzoler’s Population I (summer), and we detected higher longevity (45-48 years) as compared with the recorded in the available information.(AU)

Estudos de idade e crescimento de peixes têm aplicação direta na biologia pesqueira e contribuem para medidas de conservação. Nosso objetivo foi atualizar informações sobre parâmetros de crescimento de Micropogonias furnieri utilizando leitura de anéis etários em otólitos sagittae, esperando que a população do Sudeste do Brasil alcance maior longevidade do que o reportado na literatura. Examinamos 286 indivíduos, capturados entre agosto de 2010 e julho de 2011, na Baía de Ubatuba, SP. O comprimento total variou de 200-480 mm. Foram determinados os parâmetros de crescimento: Machos, L∞ = 523,4 mm, k = 0,05 ano-1, t0 = -8,78 ano; Fêmeas, L∞ = 573,5 mm, k = 0,06 ano-1, t0 = -7,49 ano. O IM e a porcentagem do tipo de borda evidenciaram o padrão de formação anual de anéis no outono/inverno, coincidindo com mais baixas temperaturas e crescimento lento. Estes resultados diferem dos reportados para População I de Vazzoler (verão), e nós detectamos longevidade bem superior (45-48 anos) à descrita anteriormente.(AU)

Associações entre as biomassas de peixes Sciaenidae (Teleostei: Perciformes) e de camarões Penaeoidea (Decapoda: Dendrobranchiata) no litoral norte do Estado de São Paulo / Relationships among Sciaenidae fish (Teleostei: Perciformes) and Penaeoidea shrimp (Decapoda: Dendrobranchiata) biomass from the north coast of São Paulo State, Brazil

Visando analisar as associações entre as biomassas de peixes Sciaenidae e de camarões Penaeoidea, foram feitas amostragens com barco de arrasto nas quatro estações do ano de 2001, em um gradiente de profundidade, nas regiões de Ubatuba, Caraguatatuba e São Sebastião. Em cada transecto, foram obtidas amostras de água e de sedimento. As hipóteses de que os fatores ambientais foram diferentes entre as estações do ano e profundidades foram testadas por ANOVAs. A dependência estatística entre as biomassas de peixes (variável resposta) e as biomassas de camarões (covariável) nas três regiões, foi testada por um modelo de ANCOVA. Para quantificar as relações entre as biomassas de cada espécie foi utilizada a CCA. A importância das estações do ano e das regiões no resultado da CCA foi avaliada pelo teste de Kruskal-Wallis e da profundidade pelo teste de Spearman. Nas estações do ano, as temperaturas e salinidades foram significativamente diferentes, o que não ocorreu com matéria orgânica (MO) e o diâmetro médio do sedimento (phi = fi). Foram amostrados 378.618 g de peixes e 79.338 g de camarões, com maiores capturas no inverno e nas menores profundidades. Em Caraguatatuba foram coletadas as maiores biomassas de ambos os grupos e a correlação entre as capturas de peixes e de camarões foi negativa. Já nas demais regiões, a correlação foi positiva. Assim, os dados de Caraguatatuba foram retirados do modelo final da ANCOVA, onde 47 por cento da variabilidade na biomassa dos peixes Sciaenidae pôde ser explicada pela presença dos camarões Penaeoidea. Xiphopenaeus kroyeri foi o único fator importante na distribuição de Sciaenidae no eixo 1, enquanto o eixo 2 evidenciou indiretamente o gradiente de profundidade. Os resultados sugerem que, possivelmente, muitas espécies de peixes busquem as mesmas áreas de ocorrência dos camarões em função dos fatores abióticos ou para utilizá-los como recurso alimentar.

To study the relationships among Sciaenidae fish and Penaeoidea shrimp biomass, fieldwork was carried out in the north coast of São Paulo state, Brazil, during the four seasons of 2001. Samples were collected in transects from different depths at Ubatuba, Caraguatatuba, and São Sebastião cities. Water and sediment were collected from each transect. The hypotheses that the environmental factors were different among the seasons and depths were tested by ANOVAs. The statistical dependence among the biomasses of fishes (response variable) and the biomasses of shrimps (covariable) in the three sections was tested by an ANCOVA model. CCA was used to quantify the relationships among each species' biomass. The seasons and sections important at the CCA results were evaluated by Kruskal-Wallis test and depth by Spearman's test. The temperatures and salinities were significantly different among seasons but organic matter and phi were not. A total of 378,618 g of fish and 79,338 g of shrimp were collected and the majority was captured during the winter and in shallow transects. The greatest biomass of both groups was captured at Caraguatatuba and the correlation between fish and shrimp captures was negative. A positive correlation was found in the other areas. Therefore, data from Caraguatatuba was removed from the final ANCOVA model, in which 47 percent of Sciaenidae biomass variability was explained by the presence of Penaeoidea shrimps. Xiphopenaeus kroyeri was the only important factor in Sciaenidae distribution in the axis 1, while axis 2 indirectly evidenced the depth gradient. The results suggest that many fish species search for the same areas where shrimp occurs, related to abiotic factors, and use them as food resource.