Consumption rates are central to understanding the trophic dynamics of an ecosystem. The consumption rates of many pelagic predators are unknown, despite their importance as ecosystem regulators and fisheries resources. We present a bioenergetics model that estimates the consumption rates of a juvenile pelagic predator, tailor (Pomatomus saltatrix), during its obligate estuarine phase. Using metabolic rate to parameterise the bioenergetics model, we determined the effect of body size and temperature on the metabolic rate of tailor. Laboratory respirometry trials were used to measure the routine metabolic rate (RMR; mgO2 kg-1 hr-1) of varying-sized tailor at 18, 21, 24, 27 and 30°C. The mass-specific RMR of tailor ranged from 135.9 mgO2 kg-1 hr-1 at 18 °C, to 395.9 mgO2 kg-1 hr-1 at 30 °C (mean body size of 80g). RMR increased exponentially with temperature, with the Q10 estimated at 2.43. A linear regression between body mass and RMR was similar to previous generalised models of metabolic theory, with a scaling exponent of -0.24.
The bioenergetics model estimated the energetic costs of metabolic and growth rates in relation to body mass, water temperature, and prey type. A juvenile tailor during its ontogenetic estuarine phase needs to consume at least 3% of its body weight daily. The bioenergetics model uses estimates of tailor biomass and mortality rates to scale to population size, thereby quantifying the trophic impact of tailor in the estuarine system. Altering model parameters such as temperature, biomass, and prey, integrates the seasonal and latitudinal variation of estuaries along eastern Australia. The results of these model perturbations will be discussed. This bioenergetics model can be used to inform fisheries management of coastal resources, as well as gain insight into the trophic dynamics of estuarine ecosystems.