Cumulative impacts from human activities – including industrial fishing and ship strikes – are creating a hazardous and sometimes fatal obstacle course.
The world’s whales are facing increasing threats in their key habitats and the “blue corridors” they use to migrate through the oceans, a report has warned.
Conservation charity WWF is calling for action by countries to safeguard the marine mammals along their “whale superhighways”.
Whales play key roles in maintaining the health of the oceans and fish populations, as well as carbon storage, but six of the 13 great whale species are endangered or vulnerable to extinction despite decades of protection from whaling.
A report by WWF and marine scientists, including from the University of Southampton, Oregon State University and University of California Santa Cruz, details whale migrations and the threats they face along the way.
It draws on satellite tracking data from 845 whales collected over the past 30 years to map how species, including humpbacks, fin and blue whales, travel through oceans from breeding to key feeding grounds.
It highlights the growing dangers they face from human activity, both in their critical habitats and during migration along coasts and across oceans such as the Pacific, Indian and Atlantic, including into UK waters.
The most significant threat to whale and dolphin populations is entanglement in fishing gear and “ghost nets” which are discarded, lost or abandoned by fishermen, which kills an estimated 300,000 whales a year, the report said.
They also face overfishing which limits their food supplies, increasing ship traffic which raises the risk of being hit by vessels, underwater noise, plastic and chemical pollution and offshore oil and gas drilling.
A handful of countries still hunt whales commercially, and the mammals are also at risk from climate change, which is affecting their prey and migration times and reducing important habitats such as sea ice.
Chris Johnson, who leads the WWF protecting whales and dolphins initiative, said: “Cumulative impacts from human activities – including industrial fishing, ship strikes, chemical, plastic and noise pollution, habitat loss and climate change – are creating a hazardous and sometimes fatal obstacle course.”
WWF is calling for the international community to work together to deliver comprehensive marine protected areas (MPAs) that overlap national and international “blue corridors”.
The charity wants to see ships moved away from critical whale habitat and measures to reduce underwater noise and vessel strikes, efforts to eliminate and clean up ghost gear and reduce plastic pollution, and work to end whales being caught as “bycatch” in fisheries.
It says delivering protected blue corridors will help more than whales, who store significant amounts of carbon over their lifetime and whose waste fertilises the ocean, helping maintain populations of other species including commercial fish.
The report points to an assessment from the International Monetary Fund which estimates the intrinsic value of each great whale is more than 2 million US dollars (£1.5 million), making the global population worth more than a trillion US dollars (£740 billion).
The global whale-watching industry alone is valued at more than 2 billion US dollars (£1.5 billion) annually, the report said.
Dr Simon Walmsley, chief marine adviser at WWF UK, said: “Gentle giants like fin and humpback whales can be frequent visitors to UK seas, but – as is the case right around the world – our waters are fraught with risk, from fishing gear entanglement to ship strikes to impacts from noise pollution.
“As a newly independent coastal state and a shipping superpower, the UK can show international leadership and support ocean recovery by expanding and strengthening marine protected areas in UK seas.”
WWF is calling on the international community to come together to protect the world’s blue corridors, by supporting the UN’s High Seas Treaty, set for final negotiations in March, to deliver a robust way to establish networks of marine protected areas in the open ocean.
An Environment Department (Defra) spokesperson said all cetaceans – whales, dolphins and porpoises – are fully protected in UK waters.
They added: “The accidental capture of sensitive marine species through commercial fishing is one of the greatest threats faced by cetaceans, and through our Fisheries Act we are working, where possible, to eliminate these occurrences.
“Our upcoming UK bycatch mitigation initiative will set out a joint vision for tackling this issue across the UK.”
Emily Beament is the PA environment correspondent.