Fishing Kills One-Third Of Sea Turtles - Nature

[hatrack]

"Nearly one in three sea turtles may be killed by fishing each year, suggests a new global study.

"At this rate of mortality, you can project that some populations will go extinct in a few decades," says Graeme Hays of the University of Wales, Swansea, UK. Hays' estimates are based on records from turtles carrying satellite tags. These broadcast an animal's position, and record its dives.

Tags also record turtles being eaten - animals that suddenly move inland to a fishing village and stay there, for example, have almost certainly been taken for food. "Tourists have photographed turtles being barbecued with the transmitter still attached," says Hays.

His team pooled the data from eight tagging projects, covering 50 green, loggerhead and leatherback turtles for a total of nearly 6,000 days(1). During this time, six perished at human hands - three in Mexico and one each in Japan, Indonesia and South Africa. That equates to an annual mortality of 31%."

EDIT

http://www.nature.com/nsu/031103/031103-17.html

[dem4everydoor]

1. Bad math?

6 dead out of 50 in 20 years is an annual mortality of 2.4%

[hatrack]

2. First divide 6,000 days by 50 turtles

This gives you 120 days - a period of about four months - what the total number of "turtle-days" (kind of like man-hours) break down to on the calendar.

Six turtles killed out of 50 tracked is a mortality rate of 12% over a four-month period.

Multiply by three to get a rough idea of annual mortality - approximately 36% over a 360-day period.

I don't have questions about the math, but this is a fairly small sampling population.