Initial evaluation of facial expressions and behaviours of harbour seal pups (Phoca vitulina) in response to tagging and microchipping

In all three experiments, orbital tightening increased from before to after tagging and microchipping (p < 0.0001), whereas the behaviours of looking around (p < 0.01) and struggling (p < 0.05) decreased. Blinking (p < 0.05) decreased in Experiments 1 and 2 while trembling (p < 0.01) decreased only in Experiment 1. Inter-observer reliability ranged from r = 0.82 to 0.92 for these five types of behaviour. In Experiment 2, sham treatment produced no similar changes. In Experiment 3, the procedures produced similar changes likely because the single analgesic/dosage tested was ineffective. For both observers, the subjective scoring of presence or absence of pain corresponded closely to whether or not the procedures had been performed (95% correspondence for experienced and 89% for inexperienced). These results show promise for facial expressions and other behaviours to be used to assess potentially painful procedures in seals.