Basking sharks are the second largest fish in the world, and can grow up to 12 metres long – as long as a Lothian bus!
They are gentle giants that feed mostly on microscopic zooplankton through their distinctive gaping mouths which can be over a metre wide.
The sharks can live for up to 50 years, but females do not mature until they’re 16 to 20. Basking sharks only reproduce every two to four years, meaning the species is increasingly at risk.
Basking sharks have been classified as an endangered species by the International Union for Conservation of Nature.
This is driven by multiple factors, including hunting, entanglement (including in creel lines), bycatch- when fishing gear like nets, longlines, or trawls unintentionally capture species other than the ones fishers are intentionally targeting- and the impacts of climate change, such as rising temperatures, ocean acidification and habitat alteration.
In 2020, the Sea of the Hebrides Marine Protected Area (MPA) was designated, following years of campaigning by the Marine Conservation Society, Scottish Wildlife Trust and partners.
This was a first-of-its-kind MPA spanning 3,800 square miles and was intended to provide protections for basking sharks, minke whales and seabed habitats. However, following years of delays to inshore fisheries management measures, this MPA still lacks robust measures to provide protections for these species. The Scottish Entanglement Alliance is working hard to reduce entanglement in fishing gear of basking sharks, whales and other marine animals in all Scotland’s waters.
Photo: © Mark Kirkland / Marine Conservation Society
Action Needed
- Press the Scottish Government to introduce overdue fisheries management measures for inshore Marine Protected Areas, and Priority Marine Features – including the Sea of the Hebrides MPA.
- Encourage the public to report basking shark sightings to organisations such as the Hebridean Whale & Dolphin Trust, or the Shark Trust.
- Call for measures to combat marine litter and microplastics, including the introduction of free standardised disposal facilities at all ports and harbours in Scotland, and further work on the Scottish Government’s Marine Litter Strategy to develop an evidence-based roadmap to tackle pollution from fishing and aquaculture gear.
Threats
By-catch and entanglement: As basking sharks feed near the water surface, they are at risk of by-catch in tangle nets and entanglement in creel lines. By-catch is when fishing gear like nets, longlines or trawls unintentionally capture species other than the ones fishers are intentionally targeting.
Boat-strike and harassment: Disturbances from boats can affect behaviours including feeding, courting and mating. Basking sharks can also be injured, or even killed, by propellers of passing boats.
Microplastics: Due to basking sharks feeding passively through their wide mouths, there is a risk they may ingest microplastics, which can impair digestion and nutrient uptake. Microplastics are pieces of plastic smaller than 5mm. They can be found everywhere from beaches to the deepest parts of the ocean.
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