Estimates of population parameters and consumption/biomass ratio for fishes in reservoirs, Paraná State, Brazil

Abstract

Consumption, natural mortality, and growth are important parameters for the construction for both fisheries and ecosystems models. We estimated k (growth constant of the von Bertalanffy's function), L oo 1 (asymptotic length), W oo (asymptotic weight), Ar (caudal fin index), M (natural mortality), and Q/B (consumption/biomass ratio) for several fish species inhabiting reservoirs. We explored possible relationships among these parameters for 135 fish species sampled in thirty reservoirs in the State of Paraná, southern Brazil. Maximum length (L max ) varied from 2.60 to 79.00 cm, L oo from 2.73 to 85.05 cm, W oo from 0.23 to 9,490.26 g, k from 0.01 to 2.38 yr , and Q/B from 3.31 to 67.18. Significant correlations were observed between most pairs of parameters, except for Ar and k, Ar and L oo , and for M and Q/B. The estimates presented here may be useful for constructing Ecopath models, both in Brazil and other tropical regions, where the use of ecosystem modeling is growing.O consumo, a mortalidade natural e as estimativas de crescimento são parâmetros importantes para a construção de modelos pesqueiros e ecossistêmicos. Dessa forma, neste trabalho foram calculados os parâmetros k (constante de crescimento da equação de von Bertalanffy), L oo (comprimento assintótico), W oo (peso assintótico), Ar (índice da nadadeira caudal), M (mortalidade natural) e Q/B (consumo/biomassa) para peixes em reservatórios. Além disso, foram exploradas possíveis relações entre esses parâmetros para 135 espécies de peixes amostradas em 30 reservatórios no estado do Paraná, sul do Brasil. O comprimento máximo (L max ) variou de 2,60 a 79,00 cm, L oo de 2,73 a 85,05 cm, W oo de 0,23 a 9.490,26 g, k de 0,01 a 2,38 ano -1 , Ar de 0,03 a 3,60, M de 0,16 a 2,82 ano -1 , e Q/B de 3,31 a 67,18. Correlações significativas foram observadas entre todos os pares de parâmetros, exceto para Ar e k, Ar e L oo e para M e Q/B. As estimativas aqui apresentadas podem ser úteis para a construção de modelos Ecopath, tanto em outras regiões tropicais, como no Brasil, onde os modelos ecossistêmicos estão em amplo estágio de desenvolvimento.

Population parameters of the fish fauna in a long-established Amazonian reservoir (Amapá, Brazil)

“…The population parameters recorded in the present study reflect the existence of a fish fauna at the study site with a diversity of habits and life histories, but with a predominance of short-lived, opportunist species. The values recorded for the different indices are consistent with those found for the same species or genera in other habitats (Angelini and Agostinho, 2005;Isaac et al, 2008;Gubiani et al, 2012;Freitas et al, 2014), and may provide the basis for trophic web models, such as Ecopath, that are still relatively scarce for reservoir environments (but see Angelini et al, 2006;Gubiani et al, 2011).…”

“…These characteristics are typical of species adapted for life in reservoir environments (Luiz et al, 2005), and r-strategist species tend to form the base of the food chain, given their predominance in the lowest trophic levels (Gubiani et al, 2012).…”

“…Most of the fish species analyzed in the present study can be classified as having r-type life history strategies, characterized by high rates of growth and mortality, and small body size (Sparre and Venema, 1992), combined with reduced longevity (short life cycle), given that the maximum age reached by a species tends to be inversely related to its growth and mortality rates. These characteristics are typical of species adapted for life in reservoir environments (Luiz et al, 2005), and r-strategist species tend to form the base of the food chain, given their predominance in the lowest trophic levels (Gubiani et al, 2012).…”

POPULATION ASPECTS AND RECRUITMENT OF Odontostilbe paraguayensis (CHARACIFORMES: CHARACIDAE) IN THE PARAGUAY RIVER, PANTANAL, BRAZIL

“…This may also be related to allocation of more energy to axial growth, rather than biomass (Mello et al 2009), and it means that specimens have changed their body to become more elongated (Froese 2006). R-strategists, in general, are small-sized fish and occupy the base of food chains (Gubiani et al 2012). They tend to present more increment in length than biomass in order to achieve longer lengths in a short time and, thus, to avoid predation pressure from large-sized fish (Walls et al 1990) since vulnerability decreases as the fish grows.…”

<b>Influence of an artificial dam on the fish assemblage of a Neotropical stream

“…In Brazil, there are more than 700 large reservoirs, and the area most affected by dams is the upper Paraná River basin (Agostinho, Pelicice, & Gomes, 2008). There are several works that focus on the ichthyofauna of dammed areas in neotropical river basins Gubiani, Gomes, & Agostinho, 2012;Vasconcelos, Alves, & Gomes, 2014;Ortega, Júlio, Gomes, & Agostinho, 2015); however, there are few studies that characterize the interference of dams on fish assemblages of small aquatic environments, such as streams (Gardner, Coghlan Jr., Zydlewski, & Saunders, 2011). Streams are hydrologically very important for surrounding rivers of a hydrographic basin because they directly influence the recharge (Alekseevskii, Grinevskii, Efremov, Zalavskaya, & Grigoreva, 2003), provide habitats for benthic invertebrates that process thick and fine organic particulate (Vannote et al, 1980), and act as breeding grounds for fish species that occupy other parts of the drainage basin (Rêgo, Pinese, Magalhães, & Pinese, 2008).…”