Spatial distribution of southern brown shrimp (Farfantepenaeus subtilis) on the Amazon continental shelf: a fishery, marine geology and GIS integrated approach

Abstract

The spatial distribution of the southern brown shrimp Farfantepenaeus subtilis (Pérez-Farfante, 1967) was studied based on industrial fishing fleet activities and is associated with geological and oceanographic characteristics of the benthonic environments on the Amazon continental shelf. Using a geographical information system (GIS) this paper sought to calculate the relative abundance of brown shrimp based on catch per unit effort (CPUE) and compare it with bathymetry, type of sedimentary structure, sedimentation rate and bottom salinity. As a result, we have concluded that the relative abundance (in terms of CPUE) is not uniformly distributed in space. Spatial analysis indicates that commercial trawling efforts were made in the (foreset) region of the subaqueous Amazon delta at depths of 40 to 60 m. In this region, prawn are responsible for the bioturbation of the sediments and the creation of a sedimentary structure called mottled mud. In the foreset region, sedimentation rates progressively increased up to 10 cm.yr-1; re-suspension was reduced and bottom salinity was high (~ 36). It appears that all of these factors define a stable muddy area with intense bioturbation. This notable biological activity is to be explained by the occurrence of a high F. subtilis abundance that appears to originate in a microbial loop. We concluded that by combining fishery information with environmental data from a GIS, it was possible to identify abundance distribution patterns for southern brown shrimp and other economically important fishery resources and to understand how they change on a large spatial-scale.

Invertebrates assemblage captured by a pink shrimp's fishery on Amazon continental shelf

“…The abundance of the crab C. ornatus was the most closely correlated with temperature, consistent with several studies in Brazil's subtropical regions (Andrade et al 2013, Watanabe et al 2014. The abundance of the target species, F. subtilis, is also inversely proportional to temperature (Martins et al 2015). This systematic association implies that monitoring fluctuations in temperature can offer a practical means of predicting possible biological change scenarios in any study system.…”

Sobre a carcinofauna acompanhante na pesca industrial do camarão-rosa na plataforma continental Amazônica

“…Dos 152 lances de pesca amostrados, 72 foram realizados na época de chuva, concentrados na faixa de profundidade entre < 40 a 60 m e 80 foram realizados na época de seca, onde 57,5% dos lances de pesca localizavam-se em profundidades superiores a 60 m (Tabela 2). Martins et al (2015), cujas amostragens também acompanharam a pesca industrial na região, descrevem uma frequência de ocorrência de arrastos semelhante: na foz do rio Amazonas, os arrastos se concentraram nas profundidades de 40 a 60 m (67.83%), enquanto na costa do Amapá, a maior frequência de arrastos foi registrada na faixa de 60 a 100m de profundidade (64.85%).…”

Length-based assessment of southern brown shrimp stock from trawl fisheries on the Amazon Continental Shelf

“…Most of the individuals in the 11.5-12.5 cm classes are caught around the turn of the year at depths of up to 60 meters in the shrimping grounds south of 2º N. By contrast, large individuals (15.5-16.5 cm classes) are harvested primarily in the second half of the year, at depths of over 60 meters in shrimping grounds north of 2º N (Martins et al, 2015;Peixoto et al, 2020), which are more distant from the principal landing port, at the city of Belém, in the eastern Amazon estuary (Figure 1). Natural mortality has an important effect on the size classes, also impacting the abundance of large individuals.…”