Basking Shark Welfare and Marine Conservation
Species Overview
The basking shark (Cetorhinus maximus) is the world's second-largest fish, reaching up to 12m. It filters plankton through enormously expanded gill rakers, swimming slowly near the surface with its vast mouth agape. It is a regular summer visitor to UK waters, particularly around Scotland, the Isle of Man, and Cornwall, following concentrations of zooplankton. Despite its size, it is entirely harmless to humans. It is now fully protected in UK waters.
Welfare Threats in UK Waters
Key welfare threats: vessel strike (slow-moving surface swimmers are vulnerable to boat collision, causing blunt trauma, lacerations from propellers, and death); entanglement in fishing gear (gillnets, lobster pot lines); accidental bycatch in pelagic trawls; and disturbance from wildlife tourism vessels approaching too closely. Historical targeted hunting for liver oil caused significant population declines; commercial fishing for basking sharks is now illegal in UK and EU waters.
Vessel Strike and Disturbance Protocols
Guidelines for wildlife tourism and recreational boating recommend: approaching basking sharks at low speed from the side (not from ahead); maintaining a minimum 4m distance (100m in some guidance); not surrounding or herding sharks; switching to neutral gear when alongside; and departing slowly. Disturbance causes sharks to dive and can disrupt feeding and social behaviour. The Wildlife and Countryside Act and Marine and Coastal Access Act provide legal protection against disturbance.
Research and Conservation
The Wildlife Trust's Shark Trust and Marine Conservation Society monitor UK basking shark populations through sightings data, satellite tagging, and photographic identification (dorsal fin shape provides individual identification). Satellite tag data has revealed unexpected winter behaviour: sharks dive to depths over 2000m, likely remaining deep through winter. Population trends are poorly known; improving monitoring is a conservation priority. Reducing marine plastic pollution protects the zooplankton basking sharks depend on.
Marine Protected Areas
Marine Protected Areas (MPAs) protect key UK basking shark aggregation and breeding sites. Designation of MPAs around known hotspots restricts vessel speeds and certain fishing activities. Climate change is shifting zooplankton distributions, potentially altering basking shark distribution patterns in UK waters. Long-term monitoring within MPAs, combined with improved vessel traffic management in sensitive areas, supports basking shark welfare and population recovery.