University of British Columbia scientists say images from satellites show there were 1,900 fishing weirs along the coast of the Persian Gulf during 2005 and that they caught approximately 31,000 tons of fish that year.
The seven countries in the region officially reported a catch of 5,260 tons to the U.N. Food and Agriculture Organization.
Fishing weirs, used in Southeast Asia, Africa and parts of North America, are semi-permanent traps that take advantage of tidal differences to catch a wide variety of marine species.
Some weirs can be more than 300 feet long and easily show up in satellite photos.
"This ancient fishing technique has been around for thousands of years," Dalal Al-Abdulrazzak, a doctoral student at the UBC's Fisheries Center and the study's lead author, said. "But we haven't been able to truly grasp their impact on our marine resources until now, with the help of modern technology."
Remote-sensing approaches such as satellite imagery have the potential to validate catch statistics and fisheries operations in general, the researchers said.
"Time and again we've seen that global fisheries catch data don't add up," study co-author Daniel Pauly said in a UBC release Tuesday. "Because countries don't provide reliable information on their fisheries' catches, we need to expand our thinking and look at other sources of information and new technologies to tell us about what's happening in our oceans."