Hundreds of dead Eastern Pacific green sea turtles could be headed for the shores of Costa Rica’s northwestern province of Guanacaste, say biologists and officials from the National System of Conservation Areas (SINAC).
At least 70 dead turtles were spotted on beaches and in shallow waters in northern Guanacaste on Tuesday, but reports from fishermen indicate that the death toll may be much higher.
“We have reports from fishermen whose boats are surrounded by hundreds of dead turtles,” Roger Blanco, the lead investigator for the Guanacaste Conservation Area with SINAC, told The Tico Times. “They say they are headed for shore.”
With its black shell and dark body, the rare Eastern Pacific green sea turtle sub-population is considered a separate species from the green sea turtle by some scientists. The sub-population is critically endangered both in Costa Rica and worldwide.
According to data from the conservation group the Wider Caribbean Sea Turtle Network, or Widecast, the population of Eastern Pacific green sea turtles has declined by 40 percent in the last several years in Costa Rica’s Golfo Dulce, in the southern Pacific, where at least 280 Olive Ridley turtles died in a mismanaged longline fishing expedition in January. Little data is available on Guanacaste’s green sea turtle population.
“This type of turtle is nearly extinct,” said Didiher Chacón, the Costa Rican director of Widecast. “The death of this many turtles is extremely severe for this species. We don’t know if the population can survive a massive loss like this; at the very least it will extremely hurt the population.”
Two badly wounded turtles were pulled from the carcasses and taken to the National University (UNA), north of the capital, in an attempt to save them. Veterinarians were able to save one of the turtles, which will be released tomorrow in the coastal province of Puntarenas. The other turtle died on the operating table.
UNA veterinarians are now studying some of the dead turtles to determine causes of death. The results are expected within the next two days, but Widecast workers found turtles with longline hooks in their mouths and others that had sustained blows to the head.
“This is very simple. If a turtle has a hook in its mouth, if it has been hit in the head, then it didn’t die of natural causes,” Chacón told The Tico Times. “Not all of the turtles had these types of injuries, and it is not fair to say that we are 100 percent sure that it was fishing in every case, but this is basic deduction.”
According to Blanco, northern Guanacaste has had a successful mahi mahi season, increasing the number of longline fishermen in the area. Longline fishing is legal in most of Costa Rica and is used primarily for catching mahi mahi. Although longliners are the main suspect for most environmental agencies, an official from the Costa Rican Fisheries Institute (Incopesca) has another theory.
Roberto Umaña, the head of Incopesca in Guanacaste, told The Tico Times in an interview that he has seen no evidence that would point to longline fishing. Later, in an email, Umaña revealed another suspect: dynamite. Some turtles were found swimming in circles as if they were dazed, Umaña wrote. According to the Nicaraguan Newspaper La Prensa, there was an incident of dynamite fishing in San Juan del Sur, just north of Playa Jobo in Costa Rica, where a number of dead turtles appeared, in September.
This story is developing. Read an update on the investigation into the turtle deaths here.