Several hundred fish turned up dead at the Boca of Nosara on April 8th, and the suspected culprit is red tide. While that may provoke fear that the phenomenon is here in full force, the Instituto Costarricense de Pesca y Acuicultura (INCOPESCA- Costa Rican Institute of Fishing and Agriculture) red tide commission indicates that the danger for humans is minimal.
Since February, fishers in Samara and Nosara have noticed occurrences of red tide in the Pacific Ocean, which is linked to the Gulf of Nicoya. However, according to reports from the Marine Phytoplankton Laboratory of the National University in Puntarenas, which monitors levels of the phytoplankton that causes red tide, the species of microalgae that produces toxins was present in the Gulf of Nicoya in February but not during March or April.
The important thing, according to INCOPESCA, is to be alert. If the sea appears murky and brown, it could be either red tide or mud that has been kicked up. The distinguishing factor is the smell. If the water is murky and smells foul, it could be red tide, in which case it’s best not to swim as contact could cause irritation to the skin and the mucous membrane and affect the respiratory system.