Biology of growth of Hoplias aff. malabaricus (Bloch, 1794) in a shallow pampean lake (Argentina)

Abstract

The trahira Hoplias aff. malabaricus is a top predator in pampean shallow lakes and is highly appreciated by recreational anglers and artisanal fishermen. Trahira growth from Yalca shallow lake was determined by lepidological analysis and age validated by marginal increment. When growth was fitted to the von Bertalanffy model, annual classes exhibited a bimodal pattern as a result of the presence of spring and summer annual cohorts associated with a three month spawning season, each period in turn showing different growth patterns. The trahira population-age structure at Yalca shallow lake showed a truncated profile with very low numbers of large adults and few individuals older than three to four years, thus producing an unbalanced length-structure population. Growth parameters and growth performance were similar to the corresponding parameters estimated for other shallow pampean lakes of the region, but strongly diverged from the data for those populations inhabiting subtropical and tropical environments. Such differences could be accounted for by dissimilarity in metabolic rates associated with thermal differences accompanying seasonal variability among latitudes as well as by the development of adaptive physiologic and demographic responses to cope with the high thermal amplitude and hydrologic instability observed in pampean lakes.A traíra Hoplias aff. malabaricus é um predador de topo encontrado em lagoas rasas nos Pampas, muito apreciada nas pescas comerciais e esportivas. O crescimento da traíra no lago Yalca foi determinado através de análises lepidológicas, validadas a partir do incremento marginal. O crescimento foi ajustado ao modelo de von Bertalanffy, sendo que as classes de tamanho anuais apresentaram padrão bimodal devido à presença de coortes de primavera e verão, associadas à uma longa estação reprodutiva com diferentes padrões de crescimento. A estrutura etária da traíra do lago Yalca apresentou um perfil truncado, com um número pequeno de adultos de maior porte e poucos indivíduos com mais de três ou quatro anos, produzindo uma estrutura em tamanho desbalanceada. Os parâmetros e a performance de crescimento foram similares aos estimados para outros lagos rasos da região, mas fortemente divergentes de populações encontradas em ambientes tropicais e subtropicais. Tais diferenças podem estar relacionadas à diferentes taxas metabólicas associadas à variação térmica sazonal entre latitudes e ao desenvolvimento de respostas adaptativas fisiológicas e demográficas em resposta aos padrões termais altamente variáveis e instabilidade hidrológica observados nos lagos da região dos Pampas.

Fish assemblage of a Pampean shallow lake, a story of instability

“…The observed selective mortality events during 1996 and 2007, which mainly affected two of the dominant species (P. valenciennis and C. voga), can therefore be explained by unfavourable thermal conditions associated with droughts. In turn, Balboni et al (2011) showed that the demographic structure and abundance of H. malabaricus, the top predator fish of the Pampean region, appears to be regulated by extreme cold temperatures. These situations do not represent unusual events, since were previously reported in Chascomús Lake by Freyre (1967), and in other Pampean lakes by Gómez (1996) and Colautti et al (1998).…”

“…However, understanding of the mechanisms involved in the dynamics of changes in fish assemblage over time, encompassing multiannual drought and flood cycles in the region, deserves further research. As fish assemblage reflects the influence of natural gradients, climate fluctuations and anthropogenic disturbance (Herwig et al, 2010), the study of its changes on a long-term basis, their timings and links with environmental variables become critical not only to increase ecological knowledge, but could also provide insights into the management of the fisheries that have high socio-economic relevance for the Pampean region (Baigún & Anderson, 1994;Balboni et al, 2011). Therefore, the aim of this study was to analyse the temporal variability of fish assemblage in Chascomús Lake between 1999 and 2013, to compare these results with historical records and discuss the role of precipitation cycles, critical temperatures occurrence and fish mortality events, as the potential main drivers for fish composition shifts.…”

Comparison of scale and otolith age readings for trahira,Hoplias malabaricus(Bloch, 1794), from Paraná River, Argentina

“…() reported a relatively very low growth rate value of 0.07, while Balboni et al. () report a value of 0.57. Given that the majority of past studies of trahira employed the use of scales, it is probable that the growth rates and asymptotic length were incorrectly estimated.…”

“…Historically, the major part of previously published studies of age and growth of species from South America fisheries were made with scales. In the case of trahira there were no published otolith studies (Ramírez, ; Paiva, ; Barbieri, ; Dománico et al., ; Dománico, ; Grosman et al., ; Tordecilla‐Petro et al., ; Balboni et al., ).…”

Estructura de tallas de captura y relación longitud-peso de peces nativos en el humedal Abras de Mantequilla, Ecuador

“…Las diferencias en la composición de las capturas podrían estar relacionadas con la amplia distribución y la importancia comercial de Pseudocurimata spp. en el ambiente léntico del embalse Chongón (Chicaiza & Flores, 2016 Balboni et al (2011) registraron una talla media de 48.79 cm (Lt) para Hoplias aff. malabaricus en el lago Yalca Argentina, superior a lo registrado en este estudio.…”