Marcelo Vianna

Bony fish bycatch in the southern Brazil pink shrimp (Farfantepenaeus brasiliensis and F. paulensis) fishery

Trawling for pink shrimp (Farfantepenaeus brasiliensis and F. paulensis) catches also large quantities of fish, mostly bony fish, which are discarded, as they have no commercial value. Their composition and abundance were studied in an area that corresponded to the southeastern coastline of Brazil. Ninety one species were registered. Incidental fishing affected mainly small individuals and occured throughout the year. The year round rate of bony fish to shrimp catches was 10,5:1,0. Three assemblages of bony fishes could be identified, influenced by the seasonal variation of the water masses, the predominant group being associated with the Coastal Water, another with the penetration of colder waters onto the platform (SACW) and a third group of a more homogenous distribution. The most critical period identified for the bycatch capture was the beginning of the winter, which was due to the overlapping of fish assemblages and the peak of fishing recruitment.

A better way forward for Brazil's fisheries.

In December 2014, the Brazilian Minister of the Environment released the new national red lists enumerating 2113 plants and 1173 animals threatened with extinction ([ 1 ][1]). Of the 475 aquatic species on the list, 83 are commercially exploited by fisheries, mainly as by-catch. The industrial

Reproductive strategies of two sympatric swimming crabs Callinectes danae and Callinectes ornatus (Crustacea: Portunidae) in an estuarine system, south-eastern Brazil

The present study analysed the reproductive biology of Callinectes danae and Callinectes ornatus, which are captured as by-catch from pink-shrimp trawling in Guanabara Bay. The size atgonadal maturity was 79.9 mm and 67.4 mm respectively, for C. danae and C. ornatus. The pattern of reproduction was continuous for both species; however, the gonadosomatic index analyses showed seasonal and alternating reproductive peaks in the bay. While C. danae showed reproductive peaks in the autumn and in the winter, C. ornatus showed an apparent reproductive peak in the summer and probably another in the spring. The sex-ratio of C. danae was significantly skewed in favour of females (3.0:1). However, in C. ornatus, males predominated (1.2:1). This reproductive pattern indicated that possibly the females of C. danae return to the estuary after spawning where trawling takes place, while ovigerous females of C. ornatus migrate to adjacent coastal areas around the bay.

Thorough analysis of polyhalogenated compounds in ray liver samples off the coast of Rio de Janeiro, Brazil

IntroductionFive liver samples of two different ray species (Gymnura altavela and Zapteryx brevirostris) off the coast of Rio de Janeiro, Brazil, were analyzed for their pollution with anthropogenic and naturally occurring organohalogen compounds.Material and methodsThe samples were extracted with accelerated solvent extraction, and after a clean-up procedure, organohalogen compounds were separated by a modified group separation on activated silica. Subsequent analyses were done by targeted and non-targeted gas chromatography–mass spectrometry in the electron capture negative ion mode.Results and discussion“Classic” organohalogen compounds such as polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), and technical 1,1,1-trichloro-2,2-di(4-chlorophenyl)ethane (DDT) were detected and quantified. PCBs generally exceeded the parts per million level and represented up to 90% of the total contamination of the ray livers. High concentrations were also detected for p,p′-DDE. Non-targeted full scan investigations lead to the detection of an abundant trichlorinated compound which was identified as a new DDT metabolite in biota. Different PBDE congeners and several halogenated natural products were quantified as well. In addition, polychlorinated terphenyls were identified and analyzed in the two species. Moreover, both ray species showed different fatty acid patterns and stable carbon isotope signatures.ConclusionsThe two ray species showed high concentrations of organohalogen compounds in their liver tissue. Varied δ13C values by up to 3.1‰ indicated that the two ray species were living in different habitats.

Effects of migration activity on the mortality rates of two Portunidae crabs in a tropical bay

*Universidade Federal do Rio de Janeiro, Instituto de Biologia, Depto. Biologia Marinha, Laboratorio de Biologia e Tecnologia Pesqueira, CCSBl.A, 21949-900, Cidade Universitaria, Ilha do Fundao, Rio de Janeiro, Brazil. †Universidade Federal de Sao Carlos, Depto. de Hidrobiologia, Laboratorio de Dinâmica de Populacoes de Peixes, Caixa Postal 676, 13565-905, Sao Carlos, Sao Paulo, Brazil. ‡Fundacao Universidade de Rio Grande, Depto. de Oceanografia, Laboratorio de Crustaceos Decapodes, Caixa Postal 474, 96201-900, Rio Grande, Rio Grande do Sul, Brazil. ∫Corresponding author, e-mail: keunecke@biologia.ufrj.br

Nursery areas and connectivity of the adults anadromous catfish (Genidens barbus) revealed by otolith-core microchemistry in the south-western Atlantic Ocean

The anadromous catfish, Genidens barbus, is a commercial and vulnerable species from South America. The aims of the present study were to assess whether the nursery areas can be discriminated by using microchemical signatures of lapillus otoliths, to assess the accuracy of classifying fish in relation to natal nursery area and to discuss the possibility of existence of homing behaviour. Thus, the otolith-core chemical signatures (barium (Ba):calcium (Ca), lithium (Li):Ca, magnesium (Mg):Ca, manganese (Mn):Ca, strontium (Sr):Ca, and zinc (Zn):Ca ratios) of adult fish were compared among different estuaries (De La Plata River in Argentina, and Patos Lagoon, Paranagua Bay and Guanabara Bay in Brazil). PERMANOVA analysis showed significant differences in the multi-element signatures of the otolith core among sampling sites for all cohorts (2002, 2003, 2006 and 2007), indicating that the technique has considerable potential for use in future assessments of population connectivity and nursery areas of G. barbus. Via quadratic discriminant function analysis, fish were classified to natal nursery areas with 80–100% cross-validation classification accuracies. These results suggested that a high level of spatial segregation exists in adult catfish life and homing behaviour could not be ruled out on the basis of our data.

Spatial patterns of distribution and the influence of seasonal and abiotic factors on demersal ichthyofauna in an estuarine tropical bay

This study focused on the influence of local-scale environmental factors on key metrics of fish community structure and function at Guanabara Bay, an estuarine system that differs from all other south-western Atlantic estuaries due to the influence of an annual low-intensity upwelling event during late spring and summer, between November and March, when a warm rainy climate prevails. The spatial patterns of the bottom temperature and salinity were more heterogeneous during the rainy season than the dry season, being linked to total precipitation and seasonal oceanographic events. The study identified 130 species and 45 families, placing Guanabara Bay as one of the most species-rich tropical estuarine ecosystems, far exceeding 22 other Brazilian estuaries. These results, in addition to characteristics such as a relatively well-preserved mangrove forest, high productivity and favourable conditions for the growth and reproduction of estuarine species, indicate that Guanabara Bay plays a central role in supporting large populations of fishes, including commercially important species.

Impact on a fish assemblage of the maintenance dredging of a navigation channel in a tropical coastal ecosystem

A dragagem e descarte de sedimento se destacam como atividades que geram grandes disturbios aos ecossistemas marinhos e, consequentemente tornam-se um desafio ao manejo e ordenamento costeiro. Grande parte dos estudos que abordam seus impactos e baseada em pesquisas com organismos sesseis e em ambientes temperados, criando uma lacuna no entendimento de seus efeitos sobre a ictiofauna, principalmente nas regioes tropicais. No presente estudo foram avaliadas as alteracoes na composicao e abundância da comunidade de peixes sob influencia da dragagem e descarte de sedimento na foz do Rio Caravelas, costa da regiao Nordeste do Brasil. As amostras foram obtidas em duas estacoes diretamente afetadas e em tres outras areas adjacentes. Nao houve diferenca significativa na diversidade media obtida para cada estacao, porem a estacao correspondente a area dragada apresentou o menor valor dentre as demais. As estacoes mais afastadas aparentemente nao foram influenciadas pelo empreendimento sugerindo efeitos localizados. A contribuicao do presente estudo e particularmente importante devido a proximidade com areas de alto valor de conservacao como manguezais e recifes de corais e a relevância do assunto, o qual trata de uma atividade que sugere expansao em vista do desenvolvimento da atividade portuaria.

The feeding habits of the eyespot skate Atlantoraja cyclophora (Elasmobranchii: Rajiformes) in southeastern Brazil

The stomach contents of the eyespot skate, Atlantoraja cyclophora (Regan, 1903), were examined with the goal to provide information about the diet of the species. Samples were collected off the southern coast of Rio de Janeiro, Brazil, near Ilha Grande, between January 2006 and August 2007, at a depth of about 60 m. The diet was analyzed by sex, maturity stages and quarterly to verify differences in the importance of food items. The latter were analyzed by: frequency of occurrence, percentage of weight and in the Alimentary Index. The trophic niche width was determined to assess the degree of specialization in the diet. Additionally, the degree of dietary overlap between males and females; juveniles and adults and periods of the year were defined. A total of 59 individuals of A. cyclophora were captured. Females and adults were more abundant. The quarters with the highest concentrations of individuals were in the summer of the Southern Hemisphere: Jan-Feb-Mar 06 and Jan-Feb-Mar 07. Prey items were classed into five main groups: Crustacea, Teleosts, Elasmobranchs, Polychaeta, and Nematoda. The most important groups in the diet of the eyespot skate were Crustacea and Teleosts. The crab Achelous spinicarpus (Stimpson, 1871) was the most important item. The value of the niche width was small, indicating that a few food items are important. The comparison of the diet between males and females and juveniles and adults indicates a significant overlap between the sexes and stages of maturity; and according to quarters, the importance of prey groups differed (crustaceans were more important in the quarters of the summer and teleost in Jul-Aug-Sep and Oct-Nov-Dec 06), indicating seasonal differences in diet composition. Three groups with similar diets were formed in the cluster analysis: (Jan-Feb-Mar 06 and 07); (Apr-May-Jun 06 and Jul-Aug-Sep 07); (Jul-Aug-Sep 06 and Oct-Nov-Dec 06).

Survival and Physical Damage in Swimming Crabs (Brachyura, Portunidae) Discarded from Trawling Fisheries in an Estuarine Ecosystem in Southeastern Brazil

The effects of mechanical stress caused by trawling, handling, air exposure, and discarding during fishing processes can cause irreversible damage to many bycatch organisms. The objective of this work was to evaluate quali-quantitatively the physical damage (loss of limbs) and differential survival among the portunid swimming crabs Callinectes danae Smith, 1869, Callinectes ornatus Ordway, 1863, and Achelous spinimanus (Latreille, 1819) in the pink shrimp trawling fishery in Guanabara Bay, Brazil. Physical damage was quantified by the incidence of lesions for each species in the following categories: male and female; juvenile and adult; and moulting and non-moulting organisms. The percentage of survivors was obtained through a 24-hour experiment in three consecutive days. The most frequently damaged species was C. danae; 58.9% of this species was observed to be injured. C. ornatus and A. spinimanus presented similar injury frequencies with injuries observed, respectively, in 44.3% and 43.5% of individuals of these species. The Chi-square value for male vs. female; juvenile vs. adult; and moulting vs. non-moulting organisms of each species did not exhibit significant differences except for adults and juveniles of C. danae. The most common type of damage observed among the species was the loss of chelipeds and/or pereiopods. Variance analysis did not detect significant differences in the survival of the various species at the different times of the experiment. The three species presented high survival percentages in all treatments, and live individuals of all species likely show similar recovery rates from trawling stress when returned to the sea.