Individual, spatial and inter-sex variation in somatic growth: a study of Piaractus mesopotamicus (Characiformes: Serrasalmidae), a long-distance freshwater Neotropical migratory fish

Abstract

Growth is a fundamental biological process, driven by multiple endogenous (intra-individual) and exogenous (environmental) factors that maintain individual fitness and population stability. The current study aims to assess whether individual, spatial (headwaters and floodplains) and inter-sex variation occurs in the growth of Piaractus mesopotamicus in the Cuiabá River basin. Samples were collected monthly from July 2006 to July 2007, at two areas in the Cuiabá River basin (headwaters and floodplain). Three growth models (individuals; individuals and sex factors; individuals and areas factors) were developed and compared the fish growth parameters using Akaike information criterion (AIC). The best fit to the length-at-age data was obtained by a model that considered individual variation and sex. The theoretical maximum average length (L ∞ ) was 64.99 cm for females, and 63.23 cm for males. Females showed a growth rate (k) of 0.230 yr -1 and males of 0.196 yr -1 . Thus, could be concluded that individual variability and sex were the main sources of variation in P. mesopotamicus somatic growth parameters.Keywords: Age, Growth models, Inter-sex variation, Otoliths, Von Bertalanffy O crescimento é um processo biológico fundamental, impulsionado por múltiplos fatores endógenos (intra-individual) e exógenos (ambientais) que mantém o fitness individual e a estabilidade populacional. Este trabalho tem como objetivo avaliar se ocorre variação individual, espacial (região de cabeceira e planície de inundação) e entre sexo no crescimento de Piaractus mesopotamicus na bacia do rio Cuiabá. Amostragens foram realizadas mensalmente entre julho de 2006 a julho de 2007, em duas áreas da bacia do rio Cuiabá (região de cabeceira e planície de inundação). Três modelos de crescimento (indivíduos, indivíduos e sexo como fator, indivíduos e área como fator) foram elaborados e comparados os parâmetros de crescimentos dos peixes com base no critério de Informação de Akaike (AIC). O melhor ajuste aos dados de comprimento na idade data foi obtido pelo modelo que considerou a variação individual e o sexo. O comprimento médio máximo teórico (L ∞ ) das fêmeas foi 64,99 cm e para os machos 63,23 cm. O coeficiente de crescimento (k) médio foi de 0,230 yr -1 e 0,196 yr -1 , respectivamente para fêmeas e machos. Portanto, pode-se concluir que variabilidade individual e sexo foram as principais origem de variação dos parâmetros de crescimento somático de P. mesopotamicus. Palavras-chave:Dimorfismo sexual, Idade, Modelos de crescimento, Otólitos,

Predicted impacts of proposed hydroelectric facilities on fish migration routes upstream from the Pantanal wetland (Brazil)

“…For now, the six peer‐reviewed studies of spawning habitat in the basin indicate that spawning habitat occurs in first through fourth order streams and many of the species are widely distributed across the PHB sub‐basins (Resende, ). Most reported spawning activity appears to happen in third and fourth order streams (Lourenço et al, ; Resende et al, ; Ziober et al, ), while the hydropower facilities in this basin are typically on fourth order and larger streams. The limited amount of spawning site data makes firm predictions premature but early data indicate that the proposed hydroelectric facilities will typically be downstream from spawning sites and that the greatest impact may be to the loss of fourth order stream spawning sites in the basin.…”

“…While there have not been any basin‐wide studies of spawning sites or ichthyoplankton abundance, there have been a handful of localized studies within the basin. These studies report the presence of ichthyoplankton (Ziober et al, ) or actively migrating adults (Lourenço et al, ; Okazaki et al, ; Pereira et al, ; Resende et al, ; Sanches & Galetti, ) at between one and eight sites within the PHB but outside of the Pantanal sub‐basin. These studies have been conducted in streams ranging from first to fourth order, and represent 35% of the 23 migratory fish species in the basin.…”

“…c Okazaki, Hallerman, de Resende, and Hilsdorf (2017). d Lourenço, Costa, Rondon, and Mateus (2017). e Resende et al (1995).…”

Idade E Crescimento De Peixes De Riacho: Métodos E Desafios Para a Obtenção De Estimativas Robustas

“…Técnicas de retrocálculo foram aplicadas em diversos estudos, incluindo aquelas de Dahl-Lea para S. brevipinna (Bervian et al 2008), Fraser-Lee para Astyanax bimaculatus (Characiformes, Characidae) (Giamas et al 1992), Myloplus rhomboidalis (Characiformes, Serrasalmidae) (Lecomte et al 1993), Plagioscion squamosissimus (Perciformes, Sciaenidae) (González et al 2005), Pseudoplatystoma orinocoense (Siluriformes, Pimelodidae) (González et al 2010) (Fernandes et al 2002), Pterodoras granulosus (Siluriformes, Doradidae) (Feitoza et al 2004), Salminus brasiliensis (Characiformes, Bryconidae) (Zuliani et al 2016) e do intercepto biológico (Campana 1990) para P. lineatus (Santana & Minte-Vera 2017) e P. mesopotamicus (Lourenço et al 2017). Essencialmente, sua aplicação serviu aos três propósitos elencados no início dessa seção.…”