Baseline metabolic rates of two Australian sharks: Mustelus antarticus and Cephaloscyllium laticeps

LICIA FINOTTO; JUAN MANUEL MOLINA; TERENCE WALKER; RICHARD REINA

North Stradbroke

Congreso; 2018 Oceania Chondrichthyan Society conference; 2018

Oceania Chondrichthyan Society

The biological differences between cartilaginous fishes, even among sharks themselves, areenormous; ecological characteristics, such as life history strategies, respiratory modes,behaviour and habitat use are among the most apparent. Extremes are represented bypelagic, actively swimming, ram ventilating sharks as opposed to bottom dwelling, sedentaryspecies capable of respiring while stationary. Corresponding to these highly variable traitsthere should be an equally high difference in baseline metabolic rates (MR; measured as O2consumption). Knowledge of MRs is essential to assess energy allocation to fundamentalprocesses. In the context of fisheries capture stress, determining the MRs of stressedanimals will allow estimating the amount of energy that, to cope with stress, has beendiverted from these other processes and their resulting impacts. However, data on MRs fordifferent shark species are very scarce, especially for large species. We determined andcompared, for the first time, the baseline MRs of two Australian species, Mustelus antarticusand Cephaloscyllium laticeps. M. antarticus is an active, pelagic, ram ventilating species,while C. laticeps is a sedentary, bottom dwelling species able to pump water through itsmouth and spiracle. Given the differences in their life strategies, a lower metabolic rate isexpected for C. laticeps. Our result showed that, M. antarticus had a higher metabolic rate(186 mg mgO2/h*kg; C. laticeps: 76.26 mgO2/h*kg), additionally it does not seem to recoverfrom the light handling stress imposed. Our results highlight that measurement of MRs areessential to interpret stress responses of species with different ecological characteristics.