The bloom of 2016
In the Southern Hemisphere's summer and autumn of 2016, the waters around Chiloé Island experienced a catastrophic harmful algal bloom (HAB). This event, locally called "Marea Roja" (Red Tide), was caused by a population explosion of the dinoflagellate Alexandrium catenella. Unusually warm ocean temperatures, partly driven by a strong El Niño, created ideal conditions for the algae. The bloom was so extensive that it led to the closure of up to 500 kilometers of coastline for shellfish harvesting.
The economic and ecological consequences were severe. The bloom killed an estimated 23 to 25 million farmed salmon, a loss of around 100,000 metric tons of product. The total financial impact on the salmon industry, Chile's second-largest export sector after copper, was estimated at $800 million. The crisis also devastated the local artisanal fishing communities, which depend on shellfish harvesting. Thousands of fishermen and seafood plant workers lost their incomes, leading to widespread social unrest and protests that isolated the island for 18 days. The situation worsened when controversial dumping of over 4,700 tons of dead salmon into the ocean by aquaculture companies, which some scientists believe may have supplied additional nutrients that intensified the toxic bloom.