Natural causes likely to blame for mass fish deaths on Costa Rica’s Caribbean coast

PUERTO VIEJO, Limón – More than seashells have been washing up with the tide along Costa Rica’s southern Caribbean coast over the past three weeks. Residents in the area have also reported dead turtles, dolphins and crabs.

Fearing possible contamination, investigators and park rangers began a series of tests last week after piles of dead fish washed up on the shores of Gandoca, Manzanillo and Punta Uva.

“The numbers made us feel like this was something abnormal,” said Donald Campbell, the head of the Environment Ministry’s Marine and Coastal Program in the Amistad-Caribe region. “Last week we began gathering fish for study.”

The University of Costa Rica released its results of the fish study on Friday. It showed that chemicals or other unnatural causes were not to blame. All of the dead fish collected were sharp-nosed pufferfish, a species associated with mass natural deaths caused from problems in reproduction and naturally occurring diseases.

“If the cause had been contamination we would have seen other dead species,” said José Masís, the administrator of the Gandoca Manzanillo Wildlife Refuge. “We don’t think these fish deaths are related to the other dead animals.”

According to Campbell, MINAE officials have not encountered much of the dead marine life reported, but they are investigating it.

“The only dead turtles we have seen washed up without heads,” he said. “There are diseases and contamination that could do this, but it looked like a predator. We are keeping our eyes open and if we see anything we will conduct the proper tests.”