Common seals are particularly vulnerable to disturbance during the June-July pupping season, when mother-pup bonding is easily disrupted by human approach and recreational activity.
Pups separated from mothers through disturbance face hypothermia from early water entry before they have developed adequate thermoregulation. Mothers frequently abandon pups at hauled-out sites disturbed by approaching people, dogs or boats. Pups stranded without mothers are unlikely to survive without rescue intervention. PDV outbreaks cause rapid population-scale mortality through immune system failure. Maintaining 100m exclusion from seal haul-out sites during pupping dramatically reduces human-caused pup mortality.