MIT-Led Team Develops
New Fish-Counting Method
By JIM CARLTON
Staff Reporter of THE WALL STREET JOURNAL
February 2, 2006 2:19 p.m.
Researchers led by the Massachusetts Institute of Technology have come up with a new system of counting fish that illuminates the ocean a million times greater than could be done in the past, providing scientists with more precise data on how much fish populations are shrinking around the world.
The remote sensor system gives researchers a snapshot of fish over a 10,000-square-kilometer area rather than the approximate 100-square-meter snapshots that could be taken before, illuminating for the first time giant fish shoals. The preliminary findings, which are coming out today in the journal Science, could give marine agencies all over the world new tools to safeguard fish stocks which experts say have been plummeting over the past century from overfishing.
"I think this is potentially revolutionary," said Jesse Ausubel, a New York-based program director for the Census of Marine Life, an international effort begun five years ago to count the world's fish. This is the kind of technology that allows wise regulation, because a lot of dispute in the ocean has to do with what is there."
The technology was developed by Nicholas Makris, an associate professor of mechanical and ocean engineering at MIT, in collaboration with other researchers at MIT, Northeastern University and the Naval Research Laboratory. Under conventional techniques, scientists measure fish populations by sailing back and forth over bodies of water and shooting high-frequency sonar waves down at the ocean bottom. The sonar beams are too narrow to reach out far into the ocean, though, and so tend to measure only the fish in the immediate vicinity, the researchers say. Researchers would take those fish counts and then extrapolate them to come up with a population estimate over a broader area.
Under the new technique, however, the MIT-led team came up with a way to use low-frequency sonar that can travel much greater distances. They say this illuminates vast parts of the ocean, revealing millions of more fish that were hidden before. In one of the more startling findings, the researchers say the sonar illuminated one shoal of fish -- possibly herring or black sea bass -- that extended 10 to 15 kilometers long. That shoal was spotted in an area off the continental shelf of the Eastern U.S., about 120 miles southeast of New York City.
"What was interesting was this shoal was shaped like an hourglass, as has been observed in small shoals," Dr. Makris said. "This could be because the shoal narrows as it is attacked by predators, like sharks."
The researchers are seeking a patent for the new technique, which is subject to more testing. They add that it is unlikely poachers would hijack the technology anytime soon, because the equipment can cost as much as $1 million and requires great scientific expertise to use.
Dr. Makris said it came about as an offshoot from another research project about four years ago, in which he used low-frequency sonar waves to map geographic features of the ocean bottom. He focused his work on the U.S.'s eastern continental shelf. "But when we started doing the work, we were seeing other stuff we couldn't recognize," Dr. Makris said. "Then we said, 'It could be fish,' and it was."
Write to Jim Carlton at [email protected]
