Salmon farming giant Mowi confirmed it suffered a sizeable die-off at its Ireland operations, the result of a toxic plankton bloom that hit its farming sites in Bantry Bay in late October.

Local media is reporting as many as 80,000 salmon worth a total of €2.4 million ($2.8 million) were killed as a result of the bloom.

The biomass on site prior to the event was 2,267 metric tons, a Mowi spokesperson confirmed to IntraFish.

Mowi Ireland has notified the Department of Agriculture, Food and the Marine (DAFM) of the incident, the spokesperson said.

The sites in question -- at Ahabeg and Roancarrig -- were affected by the toxic plankton bloom resulting in "elevated mortality rates of stock." However, at this time, "the extent of the losses have not been definitively established," said the spokesperson.

Mowi said it is in close contact with DAFM’s Aquaculture division and is strictly following all departmental and industry protocols in relation to the incident.

Company veterinary experts and site management are monitoring the situation closely with a view to establishing all relevant background detail and contributory factors as part of its investigation.

"The company regrets the loss of stock and is doing everything in its power to mitigate the impact of what is a naturally occurring toxic plankton bloom exacerbated by warmer waters which leads to the proliferation of various types of harmful plankton," said the Mowi spokesperson.

The Marine Institute as well as other experts and academics are also involved in collaborating in the various investigations to establish the exact cause of the incident.