Taxonomic Notes
There have been no published papers synonymizing this species in the last five years.
There are no taxonomic limitations relevant to taxon validation.
Justification
Rhinelepis aspera is an important species for fishing, both in the São Francisco basin and in the upper Paraná River basin. The combined effect of hydroelectric dam construction and intensive commercial fishing has led to a decline in both the São Francisco and upper Paraná populations in the last 27 years (three generations) at a rate of c. 25%; a population decline is currently also inferred. Stretches with local extinctions are already observed in the São Francisco basin, where the species is no longer recorded in its lower course; a continuing decline in mature individuals is therefore inferred. Given the moderate rates of decline in the past, this species is thus assessed as Near Threatened.
Geographic Range Information
Rhinelepis aspera has distribution in the São Francisco River basin and also in the upper Paraná River basins, occurring in Brazil and Paraguay (Ferraris Jr. 2003, Ferraris Jr. 2007). The species is believed to be extinct in the lower São Francisco, in the Brazilian states of Alagoas, Pernambuco and Sergipe (ICMBio 2018).
Population Information
Rhinelepis aspera is an important species in the fishing of the upper Paraná and São Francisco rivers. The São Francisco sub-populations are declining and possibly extinct in the lower course. In the upper Paraná River, the subpopulation increased after the formation of the Itaipu reservoir. Subsequently, and probably due to fishing and impacts from dams, there was a sharp decline in this subpopulation, which was almost completely wiped out in the region. Currently, there is evidence that the subpopulations in upper Paraná is recovering. However, in the Grande, Tietê and Paranapanema river systems, density is very low or the species is virtually extinct due to overfishing (Rosa and Lima 2008). The combined effect of hydroelectric dam construction and intensive commercial fishing is thought to have led to a decline in both the São Francisco and the upper Paraná subpopulations in the last 27 years (3 generations), at a reduction rate equating to approximately 25%.
Habitat and Ecology Information
Rhinelepis aspera inhabits river channels and feeds on debris, organic matter and insect larvae (Hahn et al. 2004, Graça and Pavanelli 2007). The species does not have parental care and migrate during the reproductive season, which runs from October to January (Suzuki et al. 2004, Graça and Pavanelli 2007). In the São Francisco basin, the species is most commonly found in the Paracatu and Preto rivers, living mainly in rapids with a stone bottom (Sato et al. 2006).
Threats Information
The main threat to Rhinelepis aspera is related to the construction of dams in association with fishing. However, according to Godinho and Godinho (2003), fishing in São Francisco currently shows evident signs of decline in some areas. Several causes may have contributed to this process, such as pollution, inappropriate land use and inadequate fishing practices. Nevertheless, the subpopulations are thought to be undergoing decline as a result of past fishing practices and current overfishing across much of the range.
The upper portion of the Paraná River comprises of the hydrographic network in the Brazilian states of Goiás, Minas Gerais, São Paulo, Mato Grosso do Sul and Paraná. In Paraná, it extends upstream from the city of Guaíra, formerly Sete Quedas, now submerged by the Itaipu reservoir. The upper Paraná basin has also been the target of anthropic action that has been intensified since 1950 (Galves et al. 2009). Among the main changes in the original features of this basin are the construction of dams for different purposes in the main channel and its tributaries. As the species is sensitive to habitat changes, practically all stretches where dams were built showed reduction or total disappearance (CESP 1998, Agostinho and Gomes 2001). The decline of subpopulations is thus closely related to habitat fragmentation, a condition that determines the need to maintain long free stretches and rapids for their conservation.
Use and Trade Information
Rhinelepis aspera is an important species in the fishing of the upper Paraná and São Francisco rivers (Rosa and Lima 2008).
Conservation Actions Information
The conservation measures for the species need to go through programs for research and monitoring of the biology of the species, as well as protection of lagoons, rivers, and regions around water bodies. Proposals for regulation, inspection and control of fishing for Rhinelepis aspera are also needed. The species is already a target in the Brazilian National Action Plan for the Conservation of Endangered Species of Aquatic Fauna in the São Francisco River Basin - PAN São Francisco (ICMBio 2015).
