Estimating energetic intake for marine mammal bioenergetic models

Cormac G Booth; Marie Guilpin; Aimee-Kate Darias-O'Hara; Janneke M Ransijn; Megan Ryder; Dave Rosen; Enrico Pirotta; Sophie Smout; Elizabeth A McHuron; Jacob Nabe-Nielsen; Daniel P Costa

doi:10.1093/conphys/coac083

Estimating energetic intake for marine mammal bioenergetic models

Conserv Physiol. 2023 Feb 4;11(1):coac083. doi: 10.1093/conphys/coac083. eCollection 2023.

Authors

Affiliations

¹ SMRU Consulting, Scottish Oceans Institute, University of St Andrews, East Sands, St Andrews, KY16 8LB, UK.
² Department of Coastal Systems, NIOZ Royal Netherlands Institute for Sea Research, 1790 AB, Den Burg, Texel, the Netherlands.
³ Department of Freshwater and Marine Ecology, IBED, University of Amsterdam,1090 GE, Amsterdam, the Netherlands.
⁴ Sea Mammal Research Unit, Scottish Oceans Institute, East Sands, University of St. Andrews, St. Andrews, KY16 8LB, UK.
⁵ Institute for the Oceans and Fisheries, University of British Columbia, 2202 Main Mall, Vancouver, BC V6T 1Z4, Canada.
⁶ Centre for Research into Ecological and Environmental Modelling, The Observatory, Buchanan Gardens, University of St. Andrews, St. Andrews, KY16 9LZ, UK.
⁷ Cooperative Institute for Climate, Ocean, and Ecosystem Studies, University of Washington, 3737 Brooklyn Ave NE, Seattle, WA, 98105, USA.
⁸ Marine Mammal Research, Department of Ecoscience, Aarhus University, Aarhus, DK-4000 Roskilde, Denmark.
⁹ Ecology and Evolutionary Biology Department, University of California Santa Cruz, 130 McAlister Way, Santa Cruz, CA, 95064, USA.

Abstract

Bioenergetics is the study of how animals achieve energetic balance. Energetic balance results from the energetic expenditure of an individual and the energy they extract from their environment. Ingested energy depends on several extrinsic (e.g prey species, nutritional value and composition, prey density and availability) and intrinsic factors (e.g. foraging effort, success at catching prey, digestive processes and associated energy losses, and digestive capacity). While the focus in bioenergetic modelling is often on the energetic costs an animal incurs, the robust estimation of an individual's energy intake is equally critical for producing meaningful predictions. Here, we review the components and processes that affect energy intake from ingested gross energy to biologically useful net energy (NE). The current state of knowledge of each parameter is reviewed, shedding light on research gaps to advance this field. The review highlighted that the foraging behaviour of many marine mammals is relatively well studied via biologging tags, with estimates of success rate typically assumed for most species. However, actual prey capture success rates are often only assumed, although we note studies that provide approaches for its estimation using current techniques. A comprehensive collation of the nutritional content of marine mammal prey species revealed a robust foundation from which prey quality (comprising prey species, size and energy density) can be assessed, though data remain unavailable for many prey species. Empirical information on various energy losses following ingestion of prey was unbalanced among marine mammal species, with considerably more literature available for pinnipeds. An increased understanding and accurate estimate of each of the components that comprise a species NE intake are an integral part of bioenergetics. Such models provide a key tool to investigate the effects of disturbance on marine mammals at an individual and population level and to support effective conservation and management.

Keywords: Bioenergetics; energy intake; marine mammals.