Basking sharks visiting UK and Irish coastal waters for summer feeding face welfare threats from vessel disturbance, entanglement, and deliberate harassment.
Basking sharks injured by boat propellers or struck by high-speed vessels suffer severe traumatic injuries that may be immediately lethal or cause fatal infections. The prolonged slow filtering behaviour of basking sharks makes them particularly vulnerable to close approach by recreational vessels. Deliberate approach and harassment — including jumping boats over surfacing sharks and attempting physical contact — causes acute stress responses and forces sharks to dive, disrupting feeding. The precautionary welfare approach of maintaining minimum 100 metre distances and zero-wake speeds near feeding sharks prevents these welfare harms. Given uncertainty about basking shark sentience, precautionary protection from human disturbance is appropriate.