Marlin the Impostor

Anglers love to get a white marlin (above) on the line. Their fantastic jumping displays are stock fodder for just about every TV program that covers ocean fishing.

But despite their best efforts to lure this particular fish to the hook, often it's the fishermen who get fooled. Not every marlin is a marlin — another billfish species known as the round scale spearfish closely resembles the over-fished white marlin. Researchers determined the fish was a white marlin phony using detailed fish scale comparisons and DNA test.

"We don't know much about roundscale spearfish, particularly how abundant they are," said Eric Prince, an NOAA Fisheries Service official and co-author of a study detailing the white marlin imposter in a recent issue of the journal Bulletin of Marine Science. "If they are abundant and if they have been consistently misidentified as white marlin in the historical landings database … then white marlin population sizes may have been overestimated in past assessments."

Meanwhile, some good news for white marlins (and for anglers): The billfish are not endangered, National Oceanic and Atmospheric Administration (NOAA) officials said this week. The conclusion that the streamlined creature is not in danger of extinction is based on the biological status of the species used to assess its Endangered Species Act eligibility.

“All indications are that the white marlin stock has grown since we last estimated the stock size in 2002,” said Roy Crabtree, NOAA's Fisheries Service southeast regional administrator. “With reduced fishing mortality the population should remain stable or continue to increase.”

It is still legal to catch white marlin for sport, but commercial efforts to catch the fish are illegal in U.S. waters.

—LiveScience staff

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Credit: Penn-Jersey Saltwater Anglers Club