Just one week ago, the National Animal Health Service (SENASA) confirmed that the high temperatures and a decrease in oxygen caused the death of thousands of fish at the Nicoya Gulf back in February 15. However, this Friday, the National University (UNA) stated they disagree with this version and that instead studies done point to the possibility of the event being related to illegal fishing.

According to biologists from the UNA the dead fish that washed ashore the Ensenada beaches, and Manzanillo in Puntarenas could not have died as a result of lack of oxygen since this would have caused the death of many different species of fish in the Nicoya Gulf, while the majority of the fish found were sardines and a few sea bass; they also stated that after careful analysis they determined the levels of dissolved oxygen in the waters of the gulf go from 2.56 mg/L to 9.75 mg/L, a range that is perfectly compatible with life, yet according to the report by the Center for the Investigation of Microscopic Structures of the University of Costa Rica the levels of oxygen found were of up to 0.1 milligrams per liter.

Regarding the hypothesis of the high temperatures, the UNA explained that the temperatures registered in the ocean range from 22⁰C (71.6⁰F) to 32⁰C (89.6⁰ F) and in the eventuality of localized abrupt changes sardines, just like other similar species, swim in search of cooler waters.

Experts confirmed that through the analysis of the digestive system and their gills no traces were found of harmful seaweed or phytoplankton.

“After a careful investigative process, specialists at the UNA, find interesting that in an marine ecosystem as diverse as the Nicoya Gulf there’s only one main species affected, and that all of the fish found are of the same size, which makes scientists and fishermen in the area consider that the massive death of fish at could have been caused by illegal fishing”, states the press release.