Feeding pattern of Salminus maxillosus (Pisces, Characidae) at Cachoeira das Emas, Mogi-Guaçu River (São Paulo State, Southeast Brazil)

Abstract

Diet of 364 specimens of the dourado (Salminus maxillosus) was studied monthly at Cachoeira das Emas from November/1996 to May/1998, considered the breeding ground of this and other migrant fishes of Mogi-Guaçu River. Only adults were found at this site, and diet consisted exclusively of fish, with predominance of Leporinus sp. Seasonal variation in feeding activity was highest during some months of the rainy and hot season (September-December), when fish composition and number of prey species consumed also changed. These modifications were primarily attributed to an increase in food availability at the site of study during the rainy season, once most of the migrant species, including small Characidae concentrate there at this time of year. Apparently diet shifts, prey availability and rainfall are intimately related, representing a combination of factors that may account for the observed patterns of resource exploitation.Key words: Salminus maxillosus, feeding, Mogi-Guaçu River, prey availability. A dieta de 364 exemplares do dourado (Salminus maxillosus) foi estudada mensalmente na região denominada Cachoeira das Emas de novembro/1996 a maio/1998, local considerado o lar de reprodução desta e de outras espécies migratórias do Rio Mogi-Guaçu. Foram capturados apenas adultos, sendo a dieta composta exclusivamente por peixes com predominância de Leporinus sp. Foi observada variação sazonal da atividade alimentar, que foi maior na estação quente e chuvosa (setembro a dezembro), época na qual a composição e o número de presas consumidas foram distintas. Essas mudanças foram basicamente atribuídas a um aumento da disponibilidade de presas no local de estudo durante o período chuvoso, visto que a maioria das espécies migratórias, incluindo pequenos Characidae, se concentra aí nessa época. Aparentemente, as mudanças na dieta de S. maxillosus, a disponibilidade de presas e a pluviosidade estão intimamente correlacionadas, representando uma combinação de fatores que explicam os padrões de exploração de recursos aqui observados. RESUMOPalavras-chave: Salminus maxillosus, alimentação, Rio Mogi-Guaçu, disponibilidade de presas.

How does diet influence the reproductive seasonality of tropical freshwater fish?: A case study of a characin in a tropical mountain river

“…The peaks of availability of different sorts of foods were not synchronized with the breeding seasons. This asynchrony is not unusual among tropical fish (Kramer, 1978;Esteves & Pinto Lobo, 2001;de Alvarenga et al, 2006), either from floodplain rivers (e.g. Bryconamericus emperador and Brycon petrosus, Kramer, 1978; Salminus brasiliensis (as Salminus maxillosus), Esteves & Pinto Lobo, 2001; Curimatella lepidura, de Alvarenga et al, 2006) or from mountain rivers (e.g.…”

“…Possibly, the nutrients from seeds were responsible for the highest proportion of fat reserves. The observation of females with the highest total prey volume during heavy rains, the increase of fat weight soon after heavy rains and subsequent increase of gonad weight on dry months indicated that resources are being stored during rainy months to be invested later in reproduction (Esteves & Pinto Lobo, 2001;TorresMejia & Ramírez-Pinilla, 2008). In some tropical fish, the capacity to build up fat reserves allows the time of spawning to be independent of the time of food abundance (Kramer, 1978;de Avarenga et al, 2006).…”

“…Most studies on the diet of tropical freshwater fish have focused on the comparison between feeding and hydrological cycle (Prejs & Prejs, 1987;Esteves & Pinto Lobo, 2001;de Alvarenga et al, 2006), but there are few analyses that have focused on the interaction between feeding and reproductive seasonality. It has been shown that many fish totally or partially shift their diets across seasons (Prejs & Prejs, 1987;Mazzoni & Rezende, 2003), and the highest feeding activity usually occurs during the rainy seasons when the availability of prey is relatively higher (Prejs & Prejs, 1987).…”

Uso do alimento por duas espécies simpátricas de Moenkhausia (Characiformes, Characidae) em um riacho da Região Centro-Oeste do Brasil

“…Insetos terrestres foram predominantes nos conteúdos estomacais ao longo de todo o período de estudo, fato amplamente estabelecido para a ictiofauna de riachos (ANGERMEIER & KARR, 1983;GARMAN, 1991;REZENDE & MAZZONI, 2006). Apesar de vários estudos sobre a alimentação de espécies de Characidae indicarem forte influência sazonal na dieta (ARANHA et al, 2000;ESTEVES & PINTO-LOBO, 2001;MAZZONI & REZENDE, 2003), para as espécies de Moenkhausia esta variável teve pouca influência, o que sugere que estes insetos estiveram disponíveis durante todo o ano. Dessa forma, ambas as espécies apresentaram hábito alimentar insetívoro, com tendência à captura de insetos terrestres, provavelmente na superfície da água.…”

Growth and survival of dorado Salminus brasiliensis (Pisces, Characidae) post-larvae cultivated with different types of food and photoperiods

“…It is a large size piscivorous species that lives in lotic environments (Britski et al, 1999), whose males can weigh up to five kg and females up to 26 kg in nature (Morais Filho and Schubart, 1955). The dorado spawns in the rainy hot season of the year in which food can be easily found even for adults (Esteves and Pinto Lôbo, 2001). In * Author for correspondence captivity, the larvae hatch with a mean (± standard deviation) length of 4.96 ± 0.18 mm (ZaniboniFilho et al, 2004) and since the beginning of the exogenous feeding post-larvae present a very intense cannibalistic behavior, which can decimate the larviculture.…”