The Araguaia river is for fish?
Evaluation of fishery based on ecossystem modeling
Ecopath with Ecosim, fishing ecosystem, fishing stock, overfishing, trophic web.
Ecosystems provide us with various ecosystem services (direct and indirect), which can produce financial benefits in favor of the economic, ecological and sociological sectors. An example is fishing, as a source of income generation. When fish stocks are extracted outside their allowed size, the result is overfishing, which causes degradation of the ecosystem and can damage the ecological and economic sectors. In this way, our objective was to evaluate the ecosystem and simulate the impact of fishing effort on the biomass of the species of a stretch of the Upper Araguaia River in the years 2013 and 2017, through the construction of a trophic web model. For this, we use the modeling software Ecopath with Ecosim and ecosystemic indicators. As a result, we obtained a model of the trophic web with the target species of fishing in the Upper Rio Araguaia section that presented defined trophic levels, with alternate control in bottom-up (producers and detritivores) and top-down (key species). Ecosystem indicators indicated that fishing had oscillations in focus between the years 2015 to 2017, with catches concentrated in species of trophic level category three, with a fall in predatory species. This shows that fishing is concentrated in different species that are part of the same trophic level. However, the indicators pointed out that this increase is minimal, informing that fishing in the Upper Rio Araguaia section is sustainable. The simulation of fishing efforts in the scenarios between 2013 and 2023 indicated a drop in biomass for future scenarios, compromising five species, three key species: Sorubimichtys planiceps, Pseudoplatystoma fasciatum and Piaractus brachypomus. The reduction in the biomass of these species should lead to a decrease in their stock and change the dynamics of the ecosystem. Phractocephalus hemioliopterus and Cichla ocellaris species indicated overfishing with fishing effort in future scenarios. Both are predatory and economically interesting species, and their reduction negatively affects ecosystem services and increases the likelihood of local extinction. In general, the scenario of decline of these species alerts us to the need for sustainable alternatives for the management of fish stocks. In this sense, as much as the indicators show us that fishing in this stretch of the Upper Araguaia River is currently sustainable, there is still a need to pay attention to fish stocks of commercial interest.