Non-native fish in aquaculture and sport fishing in Brazil: economic benefits versus risks to fish diversity in the upper River Paraná Basin

Abstract

Brazil has a highly diverse freshwater fish fauna and their freshwaters provide valuable provisioning ecosystem services in aquaculture and sport angling, especially in the developed regions in the south. Non-native fish now comprise a substantial proportion of the total aquaculture production and value, contributing at least $US 250 million in 2008 (63% of the total value of freshwater fish aquaculture) according to the Fish and Agriculture Organisation. Much of this aquaculture activity is centred in Central and Southern Brazil, such as impounded sections of the upper River Paraná. The non-native fishes used tend to feed at relatively low trophic levels, with the most prominently species being Cyprinus carpio and Oreochromis niloticus. Ecological risk assessment suggests these species are potentially highly invasive and deleterious to the native fish diversity of invaded water bodies. Fishes introduced for the creation of sport fisheries tend feed higher trophic levels through piscivory, such as the peacock basses (Cichla species) from Amazonia. Their introductions have generally resulted in establishment and invasion, which tends to be followed by significant and rapid declines in native fish diversity as a consequence of increased predation pressure. Thus, whilst non-native fish in the upper Paraná River support provisioning ecosystem services of substantial economic value, the principal species used represent high risks to fish diversity and conservation. It is recommended local management should concentrate on reducing these risks through use of more appropriate species in these ecosystem services, with these decisions derived using risk assessment and precautionary principles.

Population structure and reproductive period of two introduced fish species in a Brazilian semiarid region reservoir

“…Our results are also in agreement with other studies of introduced species that established successfully in many reservoirs in Brazil (Santos, Rocha, & Frédou, 2010;Chellappa et al, 2003;Santos, Silva, & Viana, 2003;Novaes et al, 2004; Bennemann, Carpa, Galvez, & Shibatta, 2006;Gomes, Dias, & Branco, 2008;Stefani & Rocha, 2009) and other countries (Japsen et al, 1997;Muñoz et al, 2006). Introduced species are extremely difficult to eradicate (Britton & Orsi, 2012), but a proposal to manage and control them is necessary to minimize their potentially harmful effects on the local aquatic community. We suggest that managers encourage artisanal fisheries and sport fishing to target these species in the reservoir and that any norm of protection for these species should be drawn.…”

“…In Brazil, in order to mitigate the reservoir construction negative effects on fish fauna and fishery resources, the main measure adopted was stocking the reservoirs with the exotic Amazonian species of Plagioscion squamosissimus, Sciaenidae (Heckel, 1840) and Cichla monoculus, Cichlidae Agassiz, 1831 (Agostinho, Gomes, & Pelecice, 2007). However, these species have become a threat to the aquatic ecosystem and to the native fish fauna, by decreasing the abundance of native species via competition or predation; and in some places, this has led to local extinctions as in the Upper Paraná River basin (Gozlan, Britton, Coex, & Copp, 2010;Barros, Santos, Zanncio & Dergam, 2012;Britton & Orsi, 2012).…”

“…In Brazil, in order to mitigate the reservoir construction negative effects on fish fauna and fishery resources, the main measure adopted was stocking the reservoirs with the exotic Amazonian species of Plagioscion squamosissimus, Sciaenidae (Heckel, 1840) and Cichla monoculus, Cichlidae Agassiz, 1831 (Agostinho, Gomes, & Pelecice, 2007). However, these species have become a threat to the aquatic ecosystem and to the native fish fauna, by decreasing the abundance of native species via competition or predation; and in some places, this has led to local extinctions as in the Upper Paraná River basin (Gozlan, Britton, Coex, & Copp, 2010;Barros, Santos, Zanncio & Dergam, 2012;Britton & Orsi, 2012).Plagioscion squamosissimus and C. monoculus have established population with high abundance and successfully colonized different Brazilian reservoirs such as: Itaipu, Capivara and Três Maria (Agostinho et al, 2007). Plagioscion squamosissimus can reach 80.0 cm of total length and weight 4.5 kg (Froese & Pauly, 2014), has a high fecundity and a long reproductive period with a peak during the rainy season (Godinho, Lamas, & Godinho, 2010); previous studies have shown that the first maturity (L 50 ) can vary between 17.80 cm and 32.40 cm (Carnelós & Benedito-Cecilio, 2002;Rocha, Juras, Cintra, & Souza, 2006).…”

Ichthyofauna of streams of the Lower Paranapanema River basin, state of Paraná, Brazil

“…Monitoring of non-native species with invasive potential is essential, as they may become dominant, especially in environments that are already under disturbance (Casatti et al 2009;Britton and Orsi 2012), as pointed out by Simberloff (2013) and Orsi and Britton (2014). Among the recorded species, nine were introduced in the basin and sampled mostly in the upper stretches of the Centenário Stream.…”

Heterotilapia buttikoferi (Hubrecht, 1881) (Perciformes: Cichlidae), an introduced exotic fish in the upper Paraná river basin

“…The number of fish species introduced to the Neotropical region has grown exponentially in the last decades mainly as a result of accidental escapes of captive individuals or translocation with the aim to increase artisanal fishers' income or to improve fisheries (Britton and Orsi 2012, Magalhães and Jacobi 2013, Thomaz et al 2015. Invasive species negatively affect at least 30% the native species (Speziale et al 2012).…”