The use of ventilation frequency as an accurate indicator of metabolic rate in juvenile Atlantic salmon (Salmo salar)

Abstract

Bioenergetics studies of free-living animals have long been hampered by limitations on our abilities to measure the energy costs of different activities. Here we evaluate whether it is possible to use the opercular ventilatory beat rate of a fish to estimate its rate of energy expenditure. Changes in metabolic rate (MR) and ventilation rate (VR) were recorded in yearling Atlantic salmon (Salmo salar, weight range 1.8-12.64 g) engaged in different activities at different temperatures while within a respirometer. MR was found to correlate strongly with VR in all fish. The relationship was linear, and both the slope and corresponding intercept of the regression equation were strongly dependent on the fish's body weight and the test temperature. From these relationships, a general equation was generated to predict MR at a range of temperatures from knowledge of a fish's weight and its VR; this proved to be highly accurate (correlation between predicted and observed MRs: r = 0.95), although calibration of individual fish is recommended in studies that compare performance of individuals. Visual measurements of VR may therefore provide a highly accurate, cheap, and noninvasive method of measuring the energy consumption of fish engaged in natural behaviours in more natural settings. Résumé :Les études bioénergétiques d'animaux en liberté ont longtemps été restreintes par l'impossibilité de mesurer les coûts énergétiques des différentes activités. Nous vérifions ici s'il est possible d'utiliser le taux de battement de ventilation des opercules d'un poisson pour mesurer son taux de dépense d'énergie. Nous avons enregistré dans un respiromètre les changements de taux métabolique (MR) et de taux de ventilation (VR) de saumons atlantiques (Salmo salar, étendue des masses 1,8 -12,64 g) d'un an durant diverses activités à différentes températures. Il y a une forte corrélation entre MR et VR chez tous les poissons. La relation est linéaire et la pente et l'ordonnée à l'origine correspondante de l'équation de ré-gression sont toutes deux fortement dépendantes de la masse corporelle du poisson et de la température expérimentale. À partir de ces relations, nous avons élaboré une équation générale pour prédire MR sur une gamme de températures d'après la masse du poisson et son VR. L'équation est très précise (corrélation entre les MRs prédits et observés : r = 0,95), bien nous recommandions de calibrer chacun des poissons lors d'études qui comparent les performances individuelles. Les mesures visuelles de VR peuvent ainsi constituer une méthode très précise, peu coûteuse et non effractive de déterminer la consommation d'énergie chez des poissons en train d'accomplir des comportements normaux dans des environnements plus naturels.[Traduit par la Rédaction]

Juvenile salmon with high standard metabolic rates have higher energy costs but can process meals faster

“…The magnitude and among-individual range in SMR were similar to those of individuals recorded from the same stock of fish over long time periods (Millidine et al 2008); previous work based on extensive observations has confirmed that activity is negligible in the study species given a suitable shelter in the respirometer (Millidine et al 2006), hence justifying the description of SMR. The effect of meal size on subsequent oxygen consumption rates of salmon was similar to that often observed in other animals (Secor 2009): larger meals produced a higher peak elevation and magnitude of SDA; a longer time to reach the peak oxygen consumption; and a longer duration of SDA response.…”

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“…Fish adjust respiration to match the change in oxygen demands with changing temperature in several ways, e.g., by increasing ventilation frequency (VF) (Millidine, Metcalfe, & Armstrong, 2008;Frisk, Skov, & Steffensen, 2012), improving the oxygen exchange capacity of the gill (Sollid, Weber, & Nilsson, 2005), and regulating the oxygen binding and transportation ability of blood (De Pedro, Guijarro, López-Patiño, Martínez-Álvarez, & Delgado, 2005;Morgan, Thompson, Auchinachie, & Migaud, 2008;Qiang, Yang, Wang, Kpundeh, & Xu, 2013). Co-regulation among these processes may be necessary in the case of severe temperature changes.…”

A comparison of two methods for the assessment of stress axis activity in wild fish in relation to wastewater effluent exposure

“…Similarly, a polluted environment can increase metabolic demands in fish (Beyers et al, 1999;Peles et al, 2012) which can result in higher ventilation rates (Millidine et al, 2008) which in turn might facilitate the transfer of steroids across the gill epithelium. Given that the fish were deliberately exposed to a confinement stressor during the steroid collection procedure, and that stress is associated with an increase in ventilation rate in the stickleback (Bell et al, 2010) and other species of fish (Sanches et al, 2015), it is likely that any underlying between-population differences in resting ventilation rate were obscured.…”