Metabolic rates

The mean basal metabolic rate was calculated as 4.03 ± 0.81 ml O2 min-1 kg-1, within the range of 3.0 to 7.0 ml O2 min−1 kg−1, established by previous studies on the species, and the mean peak metabolic rate after feeding as 5.65 ± 1.1 ml O2 min-1 kg-1 . As observed in similar studies, here individual differences were often apparent, as a result of differences in personality or stress levels.

Heat increment of feeding (HIF)

The mean HIF recorded was 43% higher than the resting metabolic rate. The 8 individuals were given a diet of 1 to 1.5 kg of capelin and herring, which correspond to 1659 – 2658 kcal. Literature suggests that the amount of the meal ingested affects HIF. In fact, the results show a trend of a higher meal intake resulting in a higher HIF %, with the exception however –even though not statistically significant- of the lower amount of calories resulting in the highest HIF percentage difference. This could be explained by the fact that the individual that was tested with the lowest amount, was the youngest of the group and therefore could be a sign of the elevated energetic requirements, as younger animals tend to allocate considerable energy for growth.

In general, the results presented here are similar to the study of Yeates & Houser (2008), where a 220 kg bottlenose dolphin that consumed 1800 kcal had an increase between 20% 25 min after the ingestion of the meal to 40% 60 to 100 minutes after feeding. To provide a frame of reference, the three individuals that ingested the same amount of calories in this study, who had a mean body mass of 168.77 kg, reached a maximal post-prandial increase of about 31% between 60 and 90 min after feeding. The fasted and post-prandial metabolism has been investigated by Fahlman et al. (2024) in another odontocete species the rough-toothed dolphin, where 1-2 hr after the consumption of a meal, the metabolic rate showed an increase of 29%.

Limitations and future perspectives

Even though the number of dolphins involved was higher than in any previous related research, due to the individual variation observed, future studies could incorporate an even larger sample to investigate the degree of this variation. To obtain an accurate sample in the limited time available all individuals were fed with the same diet of capelin and herring. This could prove as a limitation as existing literature suggests that the difference in HIF is also dependent on the composition of the meal. Future research could factor that in and investigate different types of food, for example only capelin or only herring, providing variability in the proportion of proteins, carbohydrates and lipids they contain. Likewise, the quantity of the fish given should be further varied, preferably with higher amounts, to examine the upwards limits of the increase in HIF. While I was able to conduct continuous measurements without the provision of food, the first trial of the post-absorptive oxygen consumption was always followed by a meal. Thus, a control trial with measurements at all same time points without providing any energy intake initially, could contribute interesting information.


Multiple studies have tried to investigate the energetic requirements of marine mammals, particularly considering human disturbances that can affect them. Models that aim to predict how disturbances may alter population levels, require understanding of the eco-physiology of the study species in order to quantify the flow of energy within the organism and between different trophic levels. Nevertheless, there is limited knowledge of physiology of marine mammals and how related constraints affect survival. The data presented in this study provide estimates on the energy requirements and respiratory physiology in multiple individuals of bottlenose dolphins under human care in different stages of the digestion process. These data will help improve estimates from bioenergetics models and contribute to our understanding of how a changing environment may alter survival in this species.