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Tagging a Fish With a Sword for a Face

Not everyone would jump at the chance to wrestle a one-ton fish with a sword for a face, but marine biologist Sam Friedrichs welcomes the opportunity.

Friedrichs works with National Geographic’s Crittercam program to attach cameras to billfish, a group of oceanic predators that includes marlins, sailfish, spearfish, and swordfish. Billfish have been known to battle sharks, so handling these pointy-faced packs of muscle is not for the faint of heart. “They’re huge, they’re powerful. Literally you do not even stand a chance in the water with one of these fish,” says Friedrichs.

The team relies on recreational anglers to catch the billfish and then battle the fish on the line anywhere from two minutes up to two hours depending on the size and species of the catch. “We don’t want to fight any longer than we have to…We want the fish to get tired because we need to grab it by the bill to put the camera on [its] side,” explains Friedrichs.

After deployment, Friedrichs helps the fish recover from its battle on the line. “I get in the water just to make sure that fish is doing all right. I get it swimming at the right orientation and get some water going over its gills so it can get going on its own,” he says.

Billfish can swim up to 60 miles per hour and travel thousands of miles in search of food, so the cameras keep up in a way that humans can’t. In 2013, a satellite tag placed on a blue marlin in Puerto Rico popped off five months and 5,000 nautical miles later in Angola, West Africa.

Friedrichs explains, “We want to see those behaviors that no one ever sees. Feeding behavior, mating behavior, socializing behavior.” Such data informs researchers of billfish “hot spots,” and helps scientists craft a viable conservation plan for the creatures, whose population has dwindled due to overfishing.

Billfish are solitary and live in what Friedrichs calls a “blue desert.” So when recent Crittercam footage showed three male billfish following a female, Friedrichs was thrilled to witness what he believes to be courtship behavior. “[The fish] were excited. You can see it with their fins all lit up … We were jumping up and down when we watched that footage.”

Learn more details about the billfish program in the Explorers Journal blog.