The creatures' demise was linked to a so-called red tide algal bloom which produces toxins fatal to the turtles, the University of El Salvador said Friday.
Between 300 and 400 dead sea turtles were washed up in Jiquilisco Bay at the end of October.
Scientists from the university and the Environment Ministry took samples at the site which were examined by experts.
How many turtles died in total remains unclear.
The Environment Ministry pointed out that the turtles' remains could have been carried quite far from their point of origin by ocean currents.
Between 300 and 400 dead sea turtles were washed up in Jiquilisco Bay at the end of October.
Scientists from the university and the Environment Ministry took samples at the site which were examined by experts.
How many turtles died in total remains unclear.
The Environment Ministry pointed out that the turtles' remains could have been carried quite far from their point of origin by ocean currents.