Intra-specific scaling of natural mortality in fish: the paradigmatic case of the European eel

Abstract

Identifying factors and processes influencing natural mortality is fundamental to the understanding of population dynamics. Metabolic theory of ecology and experimental studies at the cross-species level suggest the existence of general patterns linking natural mortality to body mass and temperature. However, there is scant evidence that similar relationships also hold at the intra-specific scale, possibly because of the relatively narrow range of sizes and temperatures experienced by most species and the effect of local adaptation, which can obscure links between temperature and vital rates. In this sense, the European eel Anguilla anguilla, a panmictic species with a wide distribution range, provides a paradigmatic case. We compiled data published in the past 30 years on eel mortality during the continental phase of the life cycle for 15 eel stocks and calibrated a general model for mortality, considering the effects of body mass, temperature, stock density and gender. Estimated activation energy (E = 1.2 eV) was at the upper extreme reported for metabolic reactions. Estimated mortality rates (ranging between 0.02 year(-1) at 8°C, low density and 0.47 year(-1) at 18°C, high density for a body mass of 100 g) were appreciably lower than those of most fishes, most likely due to the exceptionally low energy-consuming metabolism of eel.

Metabolic theory explains latitudinal variation in common carp populations and predicts responses to climate change

“…Metabolic theory of ecology has been proposed as a framework for evaluating local adaptation (Munch and Salinas 2009). However, limited information is available regarding intraspecific variation in mortality rates (Bevacqua et al 2011). We found a strong latitudinal gradient in common carp population characteristics including longevity and mortality rates that closely follow latitudinal variation in metabolic rates.…”

Changes in European eel ovary development and body and ovary chemistry during stimulated maturation under controlled conditions: preliminary data

“…It is estimated that it has dropped to a mere 1 % of its 1970 levels (Dekker 2003;Bevacqua et al 2011). Currently, the species is outside the limits of biological safety and, consequently, it has been placed on the Red List of endangered species in Europe (Belpaire et al 2009;Prigge et al 2012).…”

Modeling individual growth trajectories of the female European eel in relation to temperature and habitat-use history in the Gironde River, France

“…In addition to the direct effect of the highest temperatures on eel growth in this system, the highest thermal environments might lead to negative side effects on eel growth from the related environmental variables. Bevacqua et al (2011) suggested the possibility that the natural mortality rates of eels increase with temperature. In addition to this, river flow in the Gironde system had a strong negative relationship with temperature in recent decades (r 2 = 0.37, p < 0.001; data provided by Centre Nucléaire de Production d'Électricité du Blayais).…”