SINCE the scooped-out shells of more than 70 green sea turtles appeared in three coastal areas in the Caribbean, Coast Guard and Environment Ministry (MINAE) patrols have maintained a 24- hour watch to catch the killers and prevent further destruction.Over the course of several days last week, authorities discovered the shells on Playa Mondonguillo, a beach in Limón province that the turtles are known to visit, and two nearby coastal areas without beaches, where the turtles do not venture, a MINAE official told The Tico Times Monday.“It was an isolated event. Nothing like that had ever happened,” MINAE regional station spokesman Sergio Obando said. “We have some theories (about why they did it), but nothing certain.” HE said he believes the attack was an act of retribution for an escalated effort to control turtle hunting in the region. A law passed at the end of 2002 stiffened penalties and retracted an option to obtain official permission to hunt, and authorities in the region have since stepped up their vigilance and busted hunting and distribution rings. The law imposes one to three years of prison on turtle hunters and trappers, and three months to two years on turtle cagers who keep them for resale.The areas are not usually under round the- clock surveillance. Obando said authorities planned to maintain the heightened watch throughout this week while analyzing the risk of lowering their guard, then make a decision as to how to carry on.One arrest has been made – a man found with turtle meat and eggs. However, though it may seem the police caught a suspect red-handed, the man is not considered one of the perpetrators of the killings.TURTLE hunting is a tradition in the region, a means of feeding families that predates Columbus. Obando called it “a cultural problem” with historical roots, one to which hunting permissions have pandered; since the practice was revoked, hunting has taken on a more organized, underground character.“At its foundation, this is a business,” Obando said. “There is a market that consumes the product offered, and there is a certain kind of network (of hunters and distributors) and it has been strengthening. Now it operates as a more closed mechanism – it operates with more discretion.”The killings, he said, “could have been a sign of power, a sign of resistance to what is happening. There has always been hunting, but nothing of this kind.”ONCE numbering several million worldwide, today fewer than 200,000 green sea turtle nesting females are thought to exist. The average turtle weighs 500 pounds. Their life expectancies are unknown, but they reach sexual maturity at 15-50 years old, according to the sea animal action group Earthtrust.