A red tide has appeared this week on the coasts of Ensenada, in the State of Baja California, killing close to 10 tons of bluefin tuna, which were being fattened in an aquaculture farm. Each fattening cage holds an average of 40 tons of tuna.
After this episode, some cages were transported out to open sea to avoid further deaths.
According to fishery authorities, the microorganism, which produces red tide, are plancton and are not toxic to human life. However, because of their double flangellate characteristics and their microscopic size they are fatal to fish, as they introduce themselves into fish bronchioles, obstructing air flow and provoking death by asphyxia.
As a defense mechanism, in general, fish living in the area around the coast withdraw to the open sea, something that fish being fattened in cages are unable to do.
The fattening of bluefin tuna in marine cages off the Baja California coast is currently one of the most viable alternatives being developed in Mexican aquaculture.