Resumo: Objetivo A variabilidade na densidade e diversidade de espécies de crustáceos decápodes foi investigada em quatro ilhas com diferentes graus de perturbação antropogênica em torno da cidade de Belém, Estado do Pará. Métodos Foram obtidas amostras de 15 canais de maré utilizando armadilhas artesanais, a cada três meses, entre outubro de 2013 e maio de 2014 nas ilhas Combu, Onças, Cotijuba e Mosqueiro. Resultados A salinidade e a temperatura variaram pouco, o que é comum em um estuário amazônico tropical fortemente influenciado pelo influxo de água doce. Foram capturados um total de 8.367 decápodes, com um registro de uma espécie exótica, Penaeus monodon. Em todas as estações, a densidade e riqueza de decápodes aumentou de Combu para Mosqueiro, com a crescente proximidade do mar e maior salinidade e pH. Com exceção de Combu, a riqueza de espécies e diversidade de Margalef tendeu a ser ligeiramente maior na estação chuvosa em todas as ilhas, especialmente em Onças. A Equitabilidade e a diversidade de Shannon foram semelhantes entre as estações, mas eram mais baixas em Onças na estação seca e mais alta em Combu, diminuindo para Mosqueiro na estação chuvosa. Em geral, os índices ecológicos são semelhantes na estação seca e na transição da seca para a estação chuvosa, na estação chuvosa a dominância ocorre na Ilha de Mosqueiro. M. acanthurus, C. bocourti e P. gracillis foram associadas à estação das chuvas, enquanto que M. surinamicum prefere a estação seca. M. amazonicum e Macrobrachium sp. não têm um padrão de ocorrência sazonal definido em todas as ilhas. Conclusões Apesar das perturbações antropogênicas e da proximidade a grandes populações humanas, especialmente na Ilha do Mosqueiro, a densidade e diversidade de crustáceos decápodes parecem ser razoavelmente não afetadas no momento.

Abstract: Aim The variability in density and species diversity of decapod crustaceans was investigated on four islands with different degrees of anthropogenic disturbance around the city of Belém, State of Pará. Methods Samples were obtained from 15 creeks using artisanal traps, every three months between October 2013 and May 2014 on Combu, Onças, Cotijuba and Mosqueiro islands. Results Salinity and temperature little varied, which is common for a tropical Amazon estuary strongly influenced by freshwater inflow. A total of 8,367 decapods were captured, with one record of an exotic species Penaeus monodon. In all seasons, decapod density and richness tended to increase from Combu to Mosqueiro, with increasing proximity to the sea and higher salinity and pH. Except for Combu, species richness and Margalef diversity tended to be slightly greater in the wet season at all islands, especially Onças. Eveness and Shannon diversity did not vary greatly between seasons but were lowest at Onças in the dry season and highest at Combu, decreasing to Mosqueiro, in the wet season. In general, ecological indices are similar in the dry and transition dry to wet seasons, and in the wet season, dominance occurs at Mosqueiro Island. Macrobrachium acanthurus, C. bocourti and P. gracillis were associated with the wet season, whereas M. surinamicum prefers the dry season. M. amazonicum and Macrobrachium sp. have no well-defined seasonal pattern of occurrence at all the islands. Conclusions Despite anthropogenic disturbances and proximity to large human populations, especially on Mosqueiro Island, the density and diversity of decapod crustaceans appear to be reasonably unaffected for the moment.

Abstract Fish local knowledge is important to recognize species and contribute to conservation and management strategies. Thus, our aim was to provide diagnostic information for the rapid identification of Mugilidae species in Caeté-Taperaçu Extractive Reserve in Bragança (PA) in northern Brazil. A total of 28 fishers were interviewed using semi-structured questionnaires. Most of the interviewees have lived in their resident village since birth and have been involved in artisanal fishers for at least 12 years. Eight generic folk taxa were identified, including ‘tainha’, which was the vernacular name most used to define the Mugil genus. Each scientific species had at least two folk generic taxa and one species. Mugil curema, M. rubrioculus, and M. trichodon were all included in the same ethnospecies, ‘tainha chata’. Most of the scientific species were referred to at least once as the ethnospecies ‘caica’, this name was applied most often to Mugil brevirostris, which is the smallest species found in northern Brazil. The principal characteristics used by the fishers were morphological traits, however, some behavioral characteristics were also taken into account. These findings should contribute to the elaboration of ethnotaxonomic keys that facilitate the rapid identification of Mugil harvested by the region’s artisanal and industrial fisheries.

Resumo O conhecimento local sobre peixes é importante para reconhecer espécies e contribui para estratégias de conservação e manejo. Nosso objetivo foi fornecer informações diagnósticas para a rápida identificação das espécies de Mugilidae da região da Reserva Extrativista Marinha Caeté Taperaçu (PA), Norte do Brasil. Um total de 28 pescadores foi entrevistado por meio de questionários semiestruturados. A maioria dos entrevistados vive na sua aldeia residente desde o nascimento e está envolvida na pesca artesanal há pelo menos 12 anos. Oito táxons populares genéricos foram identificados por esses pescadores, incluindo ‘tainha’, que era o nome vernacular mais usado para definir o gênero Mugil. Cada espécie científica tinha pelo menos dois táxons genéricos populares e uma espécie. Mugil curema, M. rubrioculus e M. trichodon foram todos incluídos na mesma etnoespécie, ‘tainha chata’. A maioria das espécies científicas foi referida pelo menos uma vez como etnoespécie ‘caica’, este nome foi aplicado mais frequentemente a Mugil brevirostris, que é a menor espécie encontrada no Norte do Brasil. As principais características utilizadas pelos pescadores foram os traços morfológicos, porém, algumas características comportamentais também foram levadas em consideração. Esses achados devem contribuir para a elaboração de chaves etnotaxonômicas que facilitem a rápida identificação de Mugil capturadas pela pesca artesanal e industrial da região.

Abstract The present study aims to investigate the variability of catches by trawling fleet vessels licensed to operate under the ‘diverse fish’ license in relation to the depth gradient and the hydrological cycle of the Amazon River. For this purpose, vessels operating in this category were accompanied by on-board observers on the inner Amazon shelf, during January, April and July 2013 and in April, May, August and September 2014. A total of 115,505 kg of fish was harvested, distributed among 22 species. The flood period was the most representative, with a total of 43,122 kg, followed by the ebb period (28,749 kg), the rainy period (23,171 kg) and the dry period (20,424 kg). Kingfish (Macrodon ancylodon) was the most abundant fish in all seasons (79.7%). Significant differences were observed in fish composition in relation to the depth gradient and hydrodynamics of the Amazon River, with higher richness and diversity (Margalef index) during flood periods and at greater depths throughout the study period. We also observed a significant interaction between river flow and depth category, with more diversified fish fauna attributed to ebbs and floods in shallow and deep waters at the mouth of the Amazon River. Considering that the license for ‘diverse fish’ was established as an alternative to fishing for marine shrimp in closed season, the need for effective monitoring of this fishing system is reiterated for an efficient assessment of the impacts in the fish community structure.

This study aimed to describe the population structure of the Amazon shrimp Macrobrachium amazonicum, as well as their relative growth between the length of the cephalothorax and the total length, and between the length of the cephalothorax and the total mass of shrimps of a fluvial-estuarine plain in the State of Pará. Shrimps were sampled monthly from August 2006 to July 2007, using trawl nets, taking three replicates at each site (Arapiranga and Mosqueiro) per month, totaling 72 replicates. We caught 5,510 specimens, being 90.90% from Arapiranga Island and 9.1% from Mosqueiro Island. The highest densities occurred in July (1.33 individuals/m²), at the beginning of the dry season and in December (1.66 individuals/m²), at the beginning of the rainy season. The morphometric analysis for separate and grouped sexes resulted in negative and positive allometric growth. Ovigerous females were observed in all months, indicating continuous reproduction and the majority (67.81%) was caught during the less rainy season. The abundance and continuous reproduction of M. amazonicum show that this estuary offers conditions for the proper development of this population.

This study investigates the shrimp found in non-vegetated areas of an estuary of the Amazon River. We ascertained the input of juveniles, species' biometrics and the influence of environmental factors on the abundance of species. The samples were collected monthly, from August 2006 to July 2007, in two places in the estuary, each next to an island. For collecting, we used a manual trawl to perform three hauls per month, totaling 36 samples per site. The abundance of shrimps was estimated as a function of the density of specimens per unit area. We used the Spearman's correlation to test the hypothesis that there is significant correlation between the average of the environmental variables measured and variations in shrimp density. The Kruskal-Wallis and the Mann-Whitney tests showed that there were significant differences in environment factors (temperature and salinity) among the months and sites. We obtained 6,091 shrimps, from which 5,231 (85.88%) were caught off the Arapiranga Island and 860 (14.12%) off the Mosqueiro Island, Palaemonidae and Penaeidae were the only families recorded. Five species were collected: Macrobrachium amazonicum (Heller, 1862), Macrobrachium surinamicum Holthuis, 1948, Macrobrachium carcinus (Linnaeus, 1758), Macrobrachium rosenbergii (De Man, 1879), and Farfantepenaeus subtilis (Pérez-Farfante, 1967). The latter (pink shrimp) was found for the first time in oligohaline environments (0-8). Macrobrachium amazonicum was the most abundant species. The recruitment of M. amazonicum juveniles was continuous throughout the year. The population of M. surinamicum was composed by juveniles and adults and that of F. subtilis exclusively by juveniles. The environmental factors analyzed were variable throughout the year and seem to explain the patterns of shrimp species occurrence in the region, the variation in their abundance and juvenile recruitment.

A pesca artesanal na costa Norte do Brasil é caracterizado por um conjunto de modalidades de pesca diferentes. Utilizando uma abordagem multidisciplinar, 20 sistemas de produção pesqueira foram identificados, com características distintas em relação à tecnologia e finalidade. As características de cada sistema foram classificados em cinco dimensões (ecológicas, económicas, sociais, tecnológicos e políticos). A análise de escalonamento multidimensional revelou que alguns destes 20 sistemas têm semelhanças maiores. Assim, um total de 10 grupos distintos foram identificados.

Artisanal fishing on the northern coast of Brazil is characterized by a set of different fishery modalities. Using a multidisciplinary approach, 20 fishery production systems were identified, with distinct characteristics regarding technology and purpose. The characteristics of each system were classified into five dimensions (ecological, economic, social, technological and political). Multidimensional scaling revealed that some of these 20 systems have greater similarities. Thus, a total of 10 groups were identified.