Finding Nemo...and Other Endangered Fish A new method to tag and track fish will help protect threatened species |
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| Enlarge ImageScientists used a new technique to “tag” the larvae of panda clownfish off Papua New Guinea to determine how far from their birthplace they wandered before settling down. Clownfish live on coral reefs in peculiar harmony with sea anemones, finding protection among the anemone’s usually poisonous tentacles. (Serge Planes, Université de Perpignan) |
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| Enlarge ImageScientists tested a novel technique to chemically "tag" the otoliths, or ear bones, of clownfish larvae on coral reefs off Kimbe Island, Papua New Guinea, using the common antibiotic tetracycline. (Simon Thorrold, WHOI) |
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Scientists have long been able to tag animals on
land and follow their movements and habits. But tagging and tracking
fish through vast oceans is a Herculean task. Tagging fish larvae
smaller than a millimeter has been impossible.
Now an international research team has demonstrated
a new technique—using the common antibiotic
tetracycline and DNA fingerprinting—to track fish and determine how
fish populations
migrate and connect to one another. Such information is essential for
identifying critical marine habitats that should be set aside to
protect the estimated 70 to 80 percent of fish populations whose stocks
have been overfished or whose habitats have been disrupted by humans.
WHOI biologist Simon Thorrold and colleagues
Geoffrey Jones of James Cook University in Australia and Serge Planes
of the Université de Perpignan in France are working in Kimbe Bay,
Papua New Guinea, where anemone-filled coral reefs provide homes for
clownfish—like the hero of the movie “Finding Nemo.” Like Nemo, many clownfish are harvested to stock aquariums, and their
numbers are being depleted on reefs throughout the Pacific and Indian
Oceans.
Tetracycline is known to darken human babies’ teeth
when taken by mothers at certain stages of pregnancy, and similarly, it
darkens the otoliths, or ear bones, of fish. By exposing developing
embryos to tetracycline in specially designed incubation chambers, the
team was able to indelibly mark the otoliths of tiny clownfish before
they hatched and dispersed.
Reporting in the July 26 issue of Current Biology,
the team used these telltale tetracycline-stained otoliths to track
clownfish larvae to new anemones within 100 meters (330 feet) of their
birthplaces.
The researchers also used DNA-fingerprinting
techniques to determine if new settlers to a community were spawned by
adults within it. They found that about two-thirds of the community’s
clownfish were not born nearby—but perhaps immigrated from other
clownfish habitats more than 10 kilometers (6 miles) away.
The new tracking methods may be adapted to help preserve
other
species under pressure, Thorrold said.
— Lonny Lippsett
This research was funded by the National Science Foundation, the WHOI Ocean Life Institute, and the Australian Research Council.
Posted: October 11, 2005 [top] |
