Analysis of fishing activity in the Itá reservoir, Upper Uruguay River, in the period 2004-2009

Abstract

This study characterized fishing activity in the reservoir of the Hydroelectric Power Plant of Itá in Brazil. The reservoir is located in the Upper Uruguay River, which forms the border between the states of Santa Catarina and Rio Grande do Sul. To analyze fishing activity and the composition of ichthyofauna in the reservoir after damming, questionnaires were administered to fishermen in the region between 2004 and 2009. The results showed that fishing in the Itá reservoir can be classified as a subsistence activity performed on small vessels and usually involving the use of drift nets and handlines. Between 2004 and 2009, 292,780.10 . A total of 27 morphospecies were captured during the sample period; carp, traíra, mandi and jundiá together accounted for almost 60% of the catch. This finding indicates that fishing is centered on the capture of sedentary and short-distance migratory species. Despite their lower abundance, long-distance migratory species continue to be captured. The case of the piracanjuba, a long-distance migratory species reintroduced to the region in 2004 and still present in the catches, is particularly noteworthy. Regarding the fishermen's socioeconomic profile, all were men, most of who have engaged in the activity for more than eleven years, have a low educational level, fish with the aid of family members and list agriculture as their main economic activity. . Foram registrados os maiores valores de Captura Por Unidade de Esforço em 2006, com médias anuais de 9,69 kg pescador -1 dia -1 . Um total de 27 morfoespécies foram capturadas, com destaque para a carpa, a traíra, o mandí e o jundiá que juntas somaram quase 60% do total capturado ao longo do período estudado, indicando que a pesca está centrada na captura de espécies sedentárias e migradoras de curtas distâncias. Apesar da menor abundância, as espécies migradoras continuam sendo capturadas ao longo dos anos, em especial a piracanjuba, que foi reintroduzida na região em 2004 e que continua presente nas capturas. Em relação ao perfil socioeconômico, os pescadores são todos homens que em sua maioria, estão há mais de 11 anos na atividade, possuem baixo grau de instrução, desenvolvem a pesca com auxílio dos demais membros da família e têm a agricultura como principal atividade econômica. KeywordsPalavras-chave: recursos pesqueiros, represamentos, pesca continental.

Structure dynamics of a fish community over ten years of formation in the reservoir of the hydroelectric power plant in upper Uruguay River

“…In relation to the piranhas, contrary to that reported by traditional fishermen, who perceived an increased abundance of piranhas after the formation of the Itá reservoir (Schork et al, 2013), the relative participation in the number of S. maculatus and P. nattereri remained constant over the ten years of the study. It is possible that this difference is related to the different selectivity of the fishing gear and different locations used by the artisanal fishermen.…”

“…the jundiá Rhamdia quelen, two species that are important in regional fishing (Schork et al, 2013) and that appear to be efficiently completing their lateral reproductive migrations, using tributary rivers to spawn (Zaniboni-Filho and Schulz, 2003). According to Lemes and Garutti (2002), the constancy of occurrence reflects the biological ability that the species has in exploring the environmental resources available at a given time in the biotope.…”

“…Although classified as accidental and also vulnerable to the limitations caused by the loss of connectivity of the pristine fluvial environment, the species appears to be able to find minimal conditions to complete its life cycle within the reservoir. For the four species of large migrators caught, in addition to the conditions imposed by the dam, the pressure caused by fishing also appears to be a factor that strongly affects the abundance of their populations (Schork et al, 2013) and should also be considered.…”

Spawning and Recruitment Areas of Migratory Fish in the Uruguay River: Applying for Rivers Connectivity Conservation in South America

“…Due to a context with fishing pressure on migratory fish species in hydroelectric dam reservoirs of the upper Uruguay River (Schork et al, 2012), added to the presence of spawning areas in this region (Hermes-Silva et al, 2009;Reynalte-Tataje et al, 2012), the identification of recruitment areas in sectors affected by hydroelectric reservoirs is extremely necessary. Some specific rainfall conditions coupled with flooding dynamics may create unique hydrological opportunities in reservoir areas, which could facilitate sporadic recruitment processes (Zaniboni-Filho and Schulz, 2003; Reynalte-Tataje et al, 2008).…”

Species richness and functional structure of fish assemblages in three freshwater habitats: effects of environmental factors and management

“…The intensity of fishing in the reservoir was previously estimated at 15.7 kg ha −1 year −1 with catch per unit effort (CPUE) values estimated at 10.5 kg fisherman −1 day −1 (Novaes & Carvalho, 2009;Schork et al, 2013). The increase of fish-cage farming in Jurumirim is estimated at 2460 t year −1 , considering the current rate of production and growth potential relative to new aquaculture parks, in which the Nile tilapia Oreochromus nilotucus (L. 1758) is the main farmed species (Montanhini et al, 2015).…”