Protecting whale highways

A thousand years after Viking seafarers named the ocean the ‘whale road’, WWF and marine scientists have laid out a new map of the planet. It could be a motorists’ atlas, thick bands representing motorways, thinner strings the connecting A-roads.

Except that every road has a blue background. These are the marine superhighways along which the world’s largest whales migrate. And they do so at huge risk.

The routes on our map were created from data gathered from more than 1,000 whales. They were tracked by satellites on journeys taken over 30 years using data supplied by more than 50 research groups.

And what journeys! The great tails of baleen and toothed whales power them across enormous distances to find shifting sources of food. A giant humpback migrates from polar seas to the tropics and back, covering almost as many miles as the circumference of the Earth in less than two years.

Whale roads

Different places are important at different times of the year for different things; perhaps a seasonal bounty of zooplankton, or a nursery for the young. The track of each individual is plotted by a thin line – the thickness of the bands testifies to the consistency of the paths taken by so many whales.

This migration map is a vital part of a new report, Protecting Blue Corridors, which provides a comprehensive look at whale migrations across all oceans.

It reveals how whales are encountering multiple and growing threats from human activities in their critical ocean habitats – areas where they feed, mate, give birth and nurse their young – and along their migration superhighways, or ‘blue corridors’.

A collaborative analysis by WWF and leading marine mammal scientists from Oregon State University, the University of California Santa Cruz and the University of Southampton, it describes a situation that has become perilous.

Humankind’s rapacious exploitation of the world’s oceans has led to six of the 13 great whale species being classified as endangered or vulnerable, even after decades of protection.

Approximately 300,000 cetaceans (whales, dolphins and porpoises) are killed each year as a result of fisheries bycatch – entanglement in fishing gear such as nets and lines. Still more are snared by ‘ghost gear’ – the discarded, lost or abandoned fishing gear that litters the sea.

One of the world’s most endangered species is the North Atlantic right whale, with just 335 individuals surviving. And 288 of those animals appear to have been caught in fishing gear at least once in their lives. How many more died unnoticed?

Attacked from all sides

There’s a frightening crossover between whale superhighways and shipping lanes. Traffic rose fourfold between 1992 and 2012, and the rate is increasing. And there’s only one winner in a collision between a whale and a 500,000-tonne supertanker.

Extra sea traffic, seismic surveys, military sonar and industrial activity, such as drilling for oil, have all contributed to underwater noise levels doubling each decade since the 1960s – a catastrophe for animals that have evolved to use sound as their primary sense.

Unable to hear or vocalise over this din, whales are deprived of their ability to communicate over tens or even hundreds of miles. What’s more, as climate change heats the ocean, it’s causing shifts in both abundance and distribution of prey.

Add the scourge of toxic chemical contamination and plastic pollutants filling their stomachs uselessly, and it’s easy to understand why whales are in such grave danger. So what can be done?