After two days of sad stories about fish populations in decline here’s some hopeful news.

With sensible catch limits and sanctuaries where fishing is prohibited, we can turn the tide on ocean species decline — but only if we can enforce the laws.  Unfortunately the ocean is a huge place with few “cops on the beat” and a lot of places for illegal, unreported, and unregulated fishermen to hide.

Until now.

Last week Oceana, SkyTruth, and Google launched the public Beta of Global Fishing Watch (GFW), a free online tool that allows anyone in the world to monitor and track the activities of the world’s largest commercial fishing vessels in near real-time.

Here’s how it works:  Every ship over a certain tonnage is required to transmit Automatic Identification System (AIS) data containing its identity, location, course and speed.  The data, received by satellites and accumulated since 2012, is used to plot each ship’s movements.  To determine which boats are fishing vessels, Global Fishing Watch developed an algorithm that identifies fishing by the characteristic patterns it makes on the map.

The map shows no-fish zones and Economic Exclusion Zones where it’s easy to see if illegal fishing is going on.  Vessels that turn off their AIS transmitters or purposely falsify their GPS data are automatically suspect.

Nations at the mercy of illegal fishing are happy to use GFW. In December 2014, when the tool was still in test mode, SkyTruth analyst Bjorn Bergman (from his desk in West Virginia!) saw a Taiwanese boat fishing illegally in Palau’s protected waters. And it turned off its AIS. The boat left Palau and headed for Indonesia.  When it returned in January Bergman remotely helped Palau authorities chase it down. Read the whole story here at the GFW blog.

So if you’re wondering how the U.S. will stop illegal fishing in 582,578 square miles of the newly expanded Papahanaumokuakea Marine National Monument (surrounding the Northwestern Hawaiian Islands) the answer is:

We’ll catch them from the sky.

For more information, watch the video and visit the Global Fishing Watch website.

(video from Global Fishing Watch on YouTube)

It happened to land animals. Now it’s happening in the ocean.  The biggest die first.

Based on Earth’s current extinction rate of 1,000 times the normal background rate (predicted to become 10 times worse) scientists believe we’re at the start of the sixth mass extinction.

Stanford geoscientist Jonathan Payne wondered if the traits of extinct marine animals could predict the likelihood of extinction in today’s ocean organisms. For mollusks and vertebrates Payne and his colleagues compared ecological traits such as habitat preference and body size in past extinct and present threatened genera (genus: one level above species).  The results were surprising.

In past extinctions habitat preference was a good predictor that an animal would disappear.  That’s not the case now. In this era, the best predictor of future extinction is large body size.

The difference is us.  Human hunting pressure is driving ocean extinction.  Our demand for seafood is high (there are billions of us to feed) and we’ve become very efficient at capturing the largest fish.  Highly migratory predators like the Pacific bluefin tuna have declined precipitously.

We’ve seen this before.  At the end of the Ice Age, as human population expanded across the globe, the megafauna simultaneously went extinct.  It’s now known that sabretooth tigers, giant armadillos and woolly mammoths disappeared due to human hunting.

We humans are successful because we make tools and hunt cooperatively.  Of course we kill the largest prey first. One large animal feeds more people.

Unfortunately we don’t know when to stop.

Read more about Payne’s study here at Science Daily.

(photo of swordfish from NOAA Photo Library. photo of woolly mammoth statue in Royal BC Museum, Victoria, Canada via Wikimedia Commons. Click on the images to see the originals)

p.s. A word about the swordfish pictured above:  Swordfish are highly migratory predators whose population is in danger in many oceans around the world.  In 1998 the North Atlantic population dropped so low that fishing was suspended.  A 2009 international assessment of North Atlantic swordfish showed they had recovered in U.S. fishing areas, so fishing resumed.  Note: The fishermen who lost their lives aboard the Andrea Gail in The Perfect Storm were longline fishing for swordfish.