Guardarrecursos del MARN localizaron entre 300 y 400 tortugas marinas muertas flotando a unas 7 millas náuticas frente a Bahía de Jiquilisco pic.twitter.com/331QZc5eXX — MARN El Salvador (@MARN_SV) November 2, 2017

As many as 300 to 400 dead sea turtles were found off the coast of El Salvador in Jiquilisco Bay late last month.

Locals began to spot the decomposing sea turtle carcasses as early as October 28, but the massive die off wasn't made public until El Salvador's ministry of environment and natural resources announced the event on Twitter Thursday and provided local reporters with information.

So far, authorities are still in the process of collecting information, and details on exact numbers or the cause of the die off have been scarce. Several turtle species live in the area—hawksbills, leatherbacks, olive ridleys, and green turtles.

Thus far it appears ridleys have been the most impacted.

The die off is reminiscent of similar mortality events in 2013 and 2006, during which about 200 and 120 turtles, respectively, were found dead.

In both of these previous cases, red tide was found to be the cause of the turtles' deaths. "Red tide" is a term that commonly refers to when colonies of algal blooms grow out of control. Sometimes, depending on the specific organisms and conditions, they can become toxic for marine life. Flair ups can occur in fresh and salt water, and they can be exacerbated by runoff from chemicals like pesticides or untreated sewer water. For turtles, ingesting the toxic blooms can be deadly.

Mike Liles has lived in El Salvador for the past decade working on turtle conservation as the director of the country's branch of the Eastern Pacific Hawksbill Initiative. From his sources on the ground, Liles has learned that as many as 300 additional dead turtles may have been found in an area called Isla Tasajara 30 miles west of Jiquilisco Bay. El Salvador's environmental ministry has yet to confirm this.

Liles hesitates to blame red tide. That explanation is likely, he says, but nearly impossible to say with certainty—until tide and toxicology reports are released by the government.

Samples from the turtles' corpses have been taken to a toxicology laboratory at the University of El Salvador to determine if the turtles did in fact die from ingesting algal blooms.

Connection to Fishing?

In the past, shrimp trawling has also caused sea turtle die offs. The marine reptiles are often caught as bycatch and drown in the trawl nets that scrape across the ocean floor. El Salvador's fishing industry has been using shrimp trawlers since the sector began to boom in the 1970s.

However, since October 17, a month-long moratorium has been in effect for shrimping in El Salvadorian waters to allow the populations to rebound. Because the moratorium went into place before the turtle corpses were found, Liles thinks fishing is likely not the cause of the massive die off. But he emphasized the practice is generally still dangerous for turtles.

Alexander Gaos, an ecologist at the Conservation Ecology Lab, also hesitates to identify an exact cause until more information is released from the government.

"It seems like in the last decade its happened quite often," Gaos said of the turtle die offs.

The Big Picture

While it's one of the largest turtle die offs the country has ever experienced, Liles isn't too worried about the populations as a whole. Ridleys have been among the majority of the turtle corpses, and the species was recently downgraded from being classified as endangered to being classified as vulnerable by the International Union for the Conservation of Nature.

Liles speculated that it wasn't out of the realm of possibility that, as run off from industrial agriculture makes red tides worse and turtle populations begin to rebound, more large-scale die offs could become more common. Gaos agreed and underscored the need for more conservation programs to be in place.