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Four Dimensional Homes in the Sea

Marine Protected Areas for Whales and Dolphins

by Erich Hoyt, WDCS Senior Research Fellow and Global MPA Programme Leader

Whales need "homes" in the sea. This is what WDCS is saying as part of our Global Campaign for Marine Protected Areas. But what does that mean?

Sperm whales in the Mediterranean off Spain and Greece routinely dive a kilometer or more deep in search of squid, surfacing an hour later sometimes several kilometers away. In the Strait of Gibraltar, orcas and common dolphins may travel tens of kilometers or more on their daily range, to locate prey.

Clearly, whales and dolphins need much larger "homes" than most land animals. On land, protected areas (PAs) are two dimensional – length times width equals the area of protection. You can put up fences and you can post guards.

The sea is different. It is too vast to be fenced in. To protect the sea, you need to factor in depth as well as length and width – three dimensions. Depth extends from 100 meters close to land to up to 11 kilometers, deeper than Everest is high. But you also need to consider time.

All sailors know that the sea is constantly moving. In the North Atlantic, currents flow from southwest to northeast, from the Caribbean to Europe, the famous Gulf Stream, before turning south. All sailors dating from Columbus have travelled with currents partly driven by wind. At depth, currents move more slowly, typically North to South in the Atlantic, but they also sometimes move vertically, up or down, due to water density or submarine topography.

These vertical currents, most notably upwellings, create explosions of life – the nutrients nourishing the plant plankton. This in turn feeds the animal plankton (zooplankton) such as krill and copepods which then attract fish, squid and whales. Some places in the world’s oceans have predictable upwellings due to underwater topography but the location of upwellings varies in most places.

So we must protect these and other changes in the sea, as well as the ability of the sea to change.

For all these reasons, we need a network of large, highly protected safe havens for whales and dolphins – marine protected areas – to accommodate whale movements and changes in the sea as well as a hedge against our own ignorance about where whales will be and when.

Protecting large whale areas will have tremendous benefits for other marine animals and ecosystems, too. For example, the proposed Alborán Sea marine protected area (MPA) has nine species of whales and dolphins but it is also an important place for seabirds, turtles, sharks, tuna and other fish, all comprising various ecosystems. Making the Alborán Sea an MPA means establishing research and educational programmes, managment bodies and plans with enforcement and monitoring regimes to address threats to marine species and ecosystems. Yet the true measure of success may be subtler and more profound.

In the words of the eminent Mediterranean scientist and conservationist Giuseppe Notarbartolo di Sciara, we can only say that we are successful when we become "reasonably convinced that...whales and dolphins have noticed that something in their life has changed for the better."

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Erich Hoyt is WDCS Senior Research Fellow and Global MPA Programme Leader. He is the author of Marine Protected Areas for Whales, Dolphins and Porpoises (Earthscan, London, 2005).

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