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Out in the blue

A new map traces the movement of creatures great and small around and across the Pacific Ocean

Tim Ecott | March/April 2013

There are many reasons to love this map. Like all good maps it takes us on a journey rather than simply showing the way. By revealing some of the secrets of the largest ecosystem on Earth, the Pacific Ocean, it allows us to imagine a world of which we usually only have the briefest of glimpses, and gives scientists and ecologists new understanding of how some of the largest oceanic predators move around the Pacific, what currents, prey and seasons drive their migrations.

Officially known as TOPP (Tagging of Pacific Predators), this map is a snapshot in an album of research. Each coloured dot represents a satellite mark for one of over 2,000 individual animals from 23 different species, whose movements have been tracked for the best part of a decade (2001-09). It was compiled from the work of a legion of scientists from around the world, who criss-crossed the ocean and identified more than 6,000 new marine species. The result is the most comprehensive inventory of known marine life ever compiled; its findings will be analysed for years to come.

The TOPP data allows us to see how sooty shearwaters fly long haul from the Aleutian Islands in the northern Pacific to New Zealand, over 500km in a day and up to 80,000 kilometres in a year. It proves that leatherback turtles can swim from California to Papua New Guinea and back again in under two years, and that great white sharks travel from the west coast of the United States all the way out into the centre of the Pacific. We are still uncertain if they are congregating at predator cafés to feast, or following some ancient memory to meet and mate with others of their species.

The Pacific Ocean has been described by ocean scientists as a great blue desert. As the research shows, that depends on where you’re looking and when. For marine predators, the central waters provide slim pickings; it is the turbulent, oxygen-rich coastal fringes where nutrients flowing from the land into the sea allow plankton and larvae to multiply, and fish to congregate and breed. Seasonal currents, warmings and coolings bring periods of feast and famine at different times, which attract animals, birds and fish to mate, to nurture their young or to feed. The biggest creatures usually follow the smallest, the whales trailing the aggregations of tiny near-surface plankton – mostly zooplankton – organisms that drift with the currents in their billions. The TOPP work gives scientists an understanding of the journeys undertaken by marine predators and the data by which, they argue, mankind may be able to institute more effective protected areas, no-fishing zones or even alter the routes taken by oil tankers so that they are less likely to run down a migrating whale.

And yet there are reasons to hate this map. For thousands of years man could only guess at the mysterious movements of those fish and mammals. Here were the imperious blue whales, larger than any other animal that has ever existed; here the gargantuan blue-fin tunas, the ferocious great white sharks and the gentle leatherback turtles. When I have met whales, sharks and schooling tuna underwater I have been awed in their presence. To explain their location solely by following a temperature chart seems prosaic. There is something discomfiting about tracking the denizens of the deep with satellite markers. At the change of the seasons I like to think of them disappearing from our consciousness as if by some instinctual signal, what the naturalist Henry Beston called “an impulse from heaven that enters into their breasts”. Nature, he wrote, has “its own economy, its checks and balances, its measurements of competing life – all of this is its great marvel and has an ethic of its own.” ~ Tim Ecott
www.topp.org

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