Influence of a cage farming on the population of the fish species Apareiodon affinis (Steindachner, 1879) in the Chavantes reservoir, Paranapanema River SP/PR, Brazil

Abstract

AIM: The aim of the present study was to evaluate the diet and biological attributes of the population of Apareiodon affinis residing near net-cage fish farming activities in the Chavantes reservoir. METHODS: Samples were collected from two populations: one near the net cages (NC) and one from an area not influenced by these cages denominated the "reference site" (RS). Monthly sampling was carried out from Mar/2008 to Feb/2009. Fish were caught with a standardized effort using gill nets deployed for 14 hours. After all individuals were measured (standard length) and weighed (total weight, carcass weight , body weight without gonads). To determine the composition of the diet, the alimentary index was calculated (AI). We also calculated the length-weight relationship, condition factor, gonad-somatic index (GSI ) and reproductive potential. RESULTS: A total of 3050 individuals were caught. The results of the (AI) revealed that the item detritus was the main food used for populations of A. affinis studied in two areas (NC = 73.1% and RS = 95.7%). The use of feed on diet A. affinis was recorded for the populations of NC adding (20.5%) of the total items consumed by the population. The resident populations residing near net-cage showed higher condition factor and more reproductive period. CONCLUSIONS: The results show the ability of the species to benefit from the input of organic matter from fish farming activities, inserting a new item in their diet (ration). This work indicates that the species A. affinis managed to establish near net-cage, allocating enough energy to increase their reproductive period and maintain viable populations close to net-cage, evidenced by the high abundance. This study suggests that systems of fish farming in net-cage influence diet and biological attributes of the species A. affinis residents Chavantes reservoir, Brazil.

Dietary changes and histophysiological responses of a wild fish (Geophagus cf. proximus) under the influence of tilapia cage farm

“…Thus, considering that individuals will consume the most available food items, in this case feed pellets and mollusks, it can be inferred that the change in diet will cause changes at other levels of the food chain. This pattern of interference by cage fish farms on freshwater ecosystems has also been reported for other omnivorous species, such as Metynnis maculatus (Ramos et al, 2008;Demétrio et al, 2012), Pimelodus maculatus, Astyanax lacustris (=Astyanax altiparanae) (Ramos et al, 2013) and Apareiodon affinis (Brandão et al, 2012). This pattern is also reported in the marine environment for the wild species Boops boops (Fernandez-Jover et al, 2008;Arechavala-Lopez et al, 2011), Trachurus mediterraneus (Fernandez-Jover et al, 2007;Fernandez-Jover et al, 2008), Sardinella aurita and Trachinotus ovatus (Fernandez-Jover et al, 2008).…”

“…In this sense, the high occurrence of detritus in tropical rivers may explain its important contribution to the diet of fish, both in the control area and in the cage farm area. Moreover, the higher sedimentation rate in cage farm areas contributes to the formation of deposits of this material on the bottom and to their increased availability to fish (Brandão et al, 2012;Ramos et al, 2013;Edwards, 2015). In addition, the benthic habit, as well as the protractile and terminal mouth of the species studied herein, favors the consumption of food near the substrate (Gerking, 1994;Castro et al, 2004;Graça and Pavanelli, 2007).…”

“…Pelleted feed contains ingredients that, while favoring a positive energy balance (Edwards, 2015), can cause serious problems in the tissues and organs of the fish and thus affect the individual's fitness, with severe consequences for the long-term survival of the individual (Takashima and Hibiya, 1995;Fernandez-Jover et al, 2007). Positive energy balance has been reported for fish species from both marine (Fernandez-Jover et al, 2007;Fernandez-Jover et al, 2008;Arechavala-Lopez et al, 2011) and freshwater environments (Brandão et al, 2012;Ramos et al, 2013), with the highest condition factor for the individuals sampled in the vicinity of the cage fish farms, as a result of the feed intake. However, in this study, the results of the relative condition factor did not demonstrate influence of cage fish farm on the current nutritional condition.…”

“…In addition, interference in settlement patterns has also been reported (Agostinho et al, 2007;Mallasen et al, 2012) due to the input of organic matter from cages and the introduction of non-native species (Zanatta et al, 2010), mainly through fish escaping from cultivation (Agostinho et al, 2007). As a consequence, there may be changes in the population dynamics of wild fish with the aggregation of fish in these areas (Ramos et al, 2013;Brandão et al, 2013;Ortega et al, 2015), as well as interference with the trophic ecology (Brandão et al, 2012;Ramos et al, 2013, Edwards, 2015 and the nutritional condition of fish (increased condition factor values) (Ramos et al, 2013;Ortega et al, 2015), when fish, mainly omnivores, feed on available food pellets.…”

Integridade ambiental da represa de Jurumirim: ictiofauna e relações ecológicas

“…Além dos impactos supracitados na composição da fauna de peixes da área de influência da represa de Jurumirim, outros impactos também reduzem a sua diversidade, tais como a introdução de espécies não nativas (Brandão et al, 2009) e a criação de peixes em sistemas de tanques-rede, considerada uma outra fonte de impacto por lançar grandes quantidades de alimento na água e por proporcionar escapes de espécies não nativas corrompendo o ambiente (Brandão et al, 2012;2013a, b;Ramos et al, 2008;2013).…”