ALL SEA turtles are endangered species. A recent estimate published in the journal Ecology Letters suggests 200,000 loggerhead and 50,000 leatherback turtles may die each year in commercial fishery longlines. Total populations have declined in the past 20 years.
Disposable tubes
The light sticks used in longline fisheries resemble the disposable plastic tubes popular with children on Halloween.
The steady glow draws fish, which then find baited hooks and are caught on the lines. The lights also seem to fascinate turtles, however, which are equally likely to chomp on fish bait, or get snagged in the hooks and lines.
Thousands of loggerhead turtles die every year when they get tangled or hooked in commercial fishing longlines meant for tuna or swordfish. New research suggests the glowing light sticks that lure fish to longlines also attract turtles, according to a University of North Carolina at Chapel Hill study.
"Juvenile turtles are indiscriminant eaters and bite nearly everything small that they encounter," said Ken Lohmann, UNC-Chapel Hill professor of biology and senior author of the study.
Helping fisheries
The new findings that appear in the May 2007 issue of the journal Animal Conservation may help fisheries decrease the number of turtles caught on lines, the researchers said, according to a University of North Carolina at Chapel Hill press release.
Most longlines deploy their hooks below the depths where turtles usually swim, so shading the lights to direct illumination downward instead of upward might make the lights harder for turtles to see.
Similarly, switching to colours that turtles can't detect very well might also reduce turtle deaths.
The researchers tested loggerhead turtle's response to light sticks in a large, water-filled tank.
Turtles were placed into a soft cloth harness and tethered to an electronic tracking device that monitored their movements. Safely encased in the soft fabric and released in the tank, the turtles swam as if in the open ocean, apparently unaware that they aren't going anywhere.
Light sticks
When glowing light sticks were introduced to the tank, the turtles swam toward them, as if curious about the lights, Lohmann said.
The colour or type of the light stick did not seem to matter.
The turtles paddled toward green, blue and yellow light sticks, as well as toward both plastic chemical lightsticks and newer models based on reusable LEDs.
Both captive-raised and wild-caught juvenile turtles were attracted to glowing light sticks whether in total darkness or underneath a night sky. — Our Bureau the HINDU
Disposable tubes
The light sticks used in longline fisheries resemble the disposable plastic tubes popular with children on Halloween.
The steady glow draws fish, which then find baited hooks and are caught on the lines. The lights also seem to fascinate turtles, however, which are equally likely to chomp on fish bait, or get snagged in the hooks and lines.
Thousands of loggerhead turtles die every year when they get tangled or hooked in commercial fishing longlines meant for tuna or swordfish. New research suggests the glowing light sticks that lure fish to longlines also attract turtles, according to a University of North Carolina at Chapel Hill study.
"Juvenile turtles are indiscriminant eaters and bite nearly everything small that they encounter," said Ken Lohmann, UNC-Chapel Hill professor of biology and senior author of the study.
Helping fisheries
The new findings that appear in the May 2007 issue of the journal Animal Conservation may help fisheries decrease the number of turtles caught on lines, the researchers said, according to a University of North Carolina at Chapel Hill press release.
Most longlines deploy their hooks below the depths where turtles usually swim, so shading the lights to direct illumination downward instead of upward might make the lights harder for turtles to see.
Similarly, switching to colours that turtles can't detect very well might also reduce turtle deaths.
The researchers tested loggerhead turtle's response to light sticks in a large, water-filled tank.
Turtles were placed into a soft cloth harness and tethered to an electronic tracking device that monitored their movements. Safely encased in the soft fabric and released in the tank, the turtles swam as if in the open ocean, apparently unaware that they aren't going anywhere.
Light sticks
When glowing light sticks were introduced to the tank, the turtles swam toward them, as if curious about the lights, Lohmann said.
The colour or type of the light stick did not seem to matter.
The turtles paddled toward green, blue and yellow light sticks, as well as toward both plastic chemical lightsticks and newer models based on reusable LEDs.
Both captive-raised and wild-caught juvenile turtles were attracted to glowing light sticks whether in total darkness or underneath a night sky. — Our Bureau the HINDU
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