ABSTRACT The piramutaba, Brachyplatystoma vaillantii is a freshwater catfish that is the most abundant fishery resource in the Amazon estuary. Piramutaba trawling is done on industrial fishing scale and is characterized by the presence of many freshwater and marine bycatch species, with and without commercial value. Here we describe the bycatch of the industrial fishery of piramutaba in the Amazon estuary and evaluate the relationship of two important environmental factors, depth and salinity, with the accidental capture of freshwater and marine fishes in the Amazon estuary in the rainy and dry seasons. We identified 21 cartilaginous fish species (19.1% freshwater and 80.9% marine) and 125 bony fish species (25.6% freshwater and 74.4% marine). The bycatch included 64 species without commercial value (43% of all bycatch species), which are always discarded. Freshwater and estuarine fishes exhibited significantly higher abundances in shallower environments, while marine fishes were similarly abundant along the entire depth gradient. On the contrary, the abundance of freshwater fishes significantly decreased, and that of estuarine and marine fishes significantly increased with increasing salinity. Regarding the conservation status of the bycatch species, one is classified as vulnerable (VU), and seven as critically endangered (CR). The information on the bycatch of piramutaba fishery in the Amazon estuary is important to subsidize regional fisheries policies and the management of protected areas.

RESUMO A piramutaba, Brachyplatystoma vaillantii é um bagre de água doce que representa o recurso pesqueiro mais abundante no estuário amazônico. O arrasto da piramutaba é feito em escala industrial, caracterizado pela presença de muitas espécies de água doce e marinha capturadas de forma incidental, com e sem valor comercial. Aqui descrevemos a captura incidental da pesca industrial de piramutaba no estuário amazônico e avaliamos a relação de dois fatores ambientais, profundidade e salinidade, com a captura incidental de espécies de água doce e marinhas nas estações chuvosa e seca. Identificamos 21 espécies de peixes cartilaginosos (19,1% de água doce e 80,9% marinhos) e 125 espécies de peixes ósseos (25,6% de água doce e 74,4% marinhos). A captura incidental incluiu 64 espécies sem valor comercial (43% de todas as espécies capturadas) que sempre são descartadas. Os peixes de água doce e estuarinos exibiram abundâncias significativamente maiores em ambientes mais rasos, enquanto os peixes marinhos foram igualmente abundantes ao longo de todo o gradiente de profundidade. Inversamente, a abundância de peixes de água doce diminuiu significativamente, e a de peixes estuarinos e marinhos aumentou significativamente em salinidades maiores. Em relação ao estado de conservação das espécies capturadas, uma é reconhecida como vulnerável (VU) e sete como criticamente ameaçadas (CR). As informações sobre a captura incidental da pesca da piramutaba no estuário amazônico são fundaentais para subsidiar políticas pesqueiras regionais e gestão de áreas protegidas.

Abstract Carapace width-carapace length (CW/CLRs), carapace width-weight (CW/WRs), and carapace length-weight (CL/WR) relationships are presented for the portunid species Callinectes bocourti A. Milne Edwards, 1879, Callinectes danae Smith, 1869, and Callinectes ornatus Ordway, 1863 from the northern coast of Brazil. A total of 85 crabs were collected between May and October 2015 in intertidal zones of the Caeté, Pirabas and Salinas estuaries. All species had strong relationships between measurements with a coefficient of determination (r 2) ranging between 0.97 and 0.99. The variable most strongly related to CW was CL with 99 % of the variability provided by C. ornatus. These relationships are a useful tool for field ecologists to estimate length and/or mass of portunid species, and it is not necessary to euthanize the organism to collect body measurements. Additionally, this study describes the first reference of CW/CLRs and CL/WRs for these portunid species in the region. The Callinectes species in Amazon estuaries are still poorly studied, and there is a need for monitoring their stocks due to its importance for artisanal fishery. The present data are important for supplying biological information required for an adequate management of this fishery.

ABSTRACT Shrimp trawl fisheries constitute a major threat to continental shelves’ biodiversity, given their profound impact on benthic communities. We investigated the composition of an invertebrate assemblage impacted by this type of fishery and possible correlations of the abundance and richness with specific environmental parameters. The activities of the industrial shrimp fleet on the north coast of Brazil were monitored over two years. We analyzed 20,303 specimens belonging to seven phyla (Porifera, Cnidaria, Mollusca, Sipuncula, Annelida, Arthropoda, Echinodermata) and 154 species. There was a predominance of generalist and rare species, given that most species (86) were sporadic. Taxonomic composition patterns were complex, dynamic, and were correlated mainly with the temperature and depth of the Amazon continental shelf, the largest in extension and low depth of the South Atlantic. The crustaceans were dominant in both abundance and taxonomic richness. The influence of environmental factors on the abundance of the main species is discussed. The invertebrates are a neglected component in studies of fisheries impact and important components of the ecological structure of the Amazon coast. They are an essential group for developing a holistic fisheries management approach, which will support the sustainability of the region's fisheries and preserve local aquatic communities.