Using Google Earth To Count The World's Fish

What’s the best way to catch people taking too many fish from the ocean? It might be on your computer right now.

Fisherman are known for telling tall tales. Fish farmers, it turns out, are also likely to exaggerate (at least in certain countries).

But researchers have pioneered a new technique to monitor the world’s artificial fisheries with satellite images from Google Earth. Examining the coastline of 16 Mediterranean countries for signs of the cages in which fish farmers raise their herds, the researchers estimated the 2006 production at 225,736 tons, a shade more (but not a statistically relevant amount more) than the 199,542 tons reported to the FAO by fishermen.

The importance of the study, however, was not in the numbers. It was the novel application of Google Earth for field research from space. Several years ago, it would have been impossible or extremely expensive to obtain the necessary satellite imagery to conduct the survey. Neither of those things are true any longer.

"We show that a few people are now capable of estimating farmed fish production for 16 countries if they have the training, the patience to meticulously examine the coast, and the Internet," write the authors of the study. They described theirs methodology as an example of "the promise of the new and untraditional tool of Google Earth to collect and ground truth data."

The data showed not every country is as truthful (or accurate) as others. Greece led the mathematically challenged claiming to produce 30% less than researchers estimated in the study, while Turkey (18% higher) and Cyprus (16% higher) were also off by large margins. (The authors also claim they made conservative assumptions about production and species.)

But the real value would be if such methods could help monitor the global commercial fishing on the high seas. If independently verified, the technique could alter the global politics of fisheries management.

But it’s a big leap from the calm waters of the Mediterranean to international oceans. Europe’s backyard is particularly well suited for monitoring: More than 90% of the coastline was well documented in Google’s map database, and the UN publishes extensive statistics on the ocean cage fish industry. That made accounting for the sector relatively straightforward compared to attempts at estimating fishing production for commercial, high-seas fisheries in intentional waters or subsistence fisheries.

But there is certainly the need. The take from wild fisheries is, unlike from farms, badly underreported. At the moment, fishing fleets eager to grab as much as they can, even illegally, cost the world as much as $23.5 billion annually. Finding out how much, and by whom, would go a long way to addressing the problem.

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