Caracterização da pesca artesanal de camarão rosa Farfantepenaeus subtilis (Pérez Farfante, 1967) capturado em um estuário amazônico (Pará-Brasil).

Abstract

In the Amazon estuary, artisanal shrimp trawling is one of the most explored activities. However, data on the relationship between the capture of the pink shrimp Farfantepenaeus subtilis and Amazonian seasonality and the impact that this activity has on the fauna of the Amazonian shrimp and the ichthyofaunistic resources is below what is necessary, which directly affects the management and the management of conservation plans to mitigate the impacts generated by artisanal trawling in the Amazon region of Brazil. Sampling was carried out every two months between January 2012 and November 2017, in the Guajará-Mirim estuary, Colares-Pará, Brazil, using a network called “puçá”. The net was dragged at night during low tide, at a depth of 1.5 m for 45 minutes, in a course of 1,418 m between three collection points. The samples were stored, preserved on ice and conducted for biometric and taxonomic analysis to the Laboratory of Aquatic Ecology and Tropical Aquaculture at the Federal Rural University of the Amazon, Belém campus. Monitoring of temperature, pH and salinity was measured in situ using a multiparameter probe. Based on the rainfall regime of the last 34 years, it was possible to identify that the studied region has two distinct seasons: rainy (from January to June, heavy precipitation) and dry (from July to December, little precipitation). During the monitoring of samples from 2012 to 2016, salinity was significantly different between the dry and rainy seasons, and the average salinity was inversely proportional to the rainfall in each season. A total of 8,377 pink shrimp specimens were captured during the study period (52% females and 48% males), the average body length was 5.56 ± 1.14 cm and the average body weight was 1.25 ± 0.83 g. The highest abundance of F. subtilis was observed in the rainy season. Regarding the accompanying fauna, in the period from 2012 to 2015, 2,210 animals were collected, 22% females and 78% males of the freshwater shrimp species Macrobrachium amazonicum contributing 34.16% of the total biomass of the captured shrimp, the largest capture was in the rainy season. The average fertility was 461 eggs, with an average length and weight of 8.63 ± 1.21 cm and 5.36 ± 1.91 g. During monitoring (2012 to 2017) the total shrimp / ichthyofauna ratio was 1: 0.42 kg and the seasonal proportion was 1: 0.78 kg (rainy season) and 1: 0.22 kg (dry season). A total of 6,229 fish, belonging to 12 orders, 26 families, 44 genera and 63 species, were caught. The species have a low length and weight, being totally discarded. The greater abundance of F. subtilis was observed when the salinity of the water was low, probably coinciding with the spawning period in the coastal region, however shrimp with low length and weight are caught which may influence the ecological distribution pattern of the species in the estuarine environment and, consequently, of the fauna captured in the trawl due to the lack of selectivity of the fishing net. It is suggested that there is a decrease in the catches of pink shrimp through artisanal trawling from March to May, in order to reduce the impacts of trawling on the fauna of M. amazonicum, due to the higher incidence that occurs in the rainy season, in addition to the females captured in the reproductive period and to reduce the disposal of ichthyofauna, as a management measure in order to contribute to the conservation of species in the Guajará-Mirim estuarine environment.