Development of a visual body condition score system for juvenile harbour seals (Phoca vitulina) in rehabilitation centres

Harbour seals (Phoca vitulina) treated at rescue centres have lower survival rates than grey seals (Halichoerus grypus). Malnutrition and weight are closely associated with recovery; however, weighing them can be invasive, stressful and poses a risk of injury to staff. This project developed a non-invasive body condition score (BCS) system to monitor the body condition of juvenile harbour seals in rescue centres. Images from CCTV footage and weight data were used to develop the BCS system, which was subsequently tested using online questionnaires from a range of users. Using two different metrics, the developed four-point BCS scale had a fair (Kappa = 0.36) and substantial (Kendall = 0.654, p < 0.001) level of inter-rater reliability, and was significantly correlated to body weight (rho = 0.718, s = 164994, p <0.001). This system can be implemented in rescue centres alongside existing practices to improve weight monitoring and reduce the handling of harbour seals, with important implications for seal stress and welfare.