ASF - Mowi Admits 450,000 caged salmon died in southern Newfoundland

Map showing location of die-off at site known as "The Gorge", to the west of Bay d'Espoir

Norwegian salmon farming giant Mowi reported Tuesday that it has experienced a 450,000 fish mortality event at one of its sites in the Canadian province of Newfoundland and Labrador (NL), almost five times the number earlier reported.

The company had reported, on Sept. 11, that it had experienced 92,700 Atlantic salmon deaths at its net-pen farm known as “The Gorge”. The number, which was more than 10% of the 900,000 salmon being raised there, triggered a public notice requirement.

“The fish at the site are approximately three kilograms, and harvesting was scheduled to begin at this site before the end of the year. This development will not change those plans,” the company said in its earlier notice.

“Environmental pressures on farming activity off the coast of [NL] are most acute at the end of summer, when site conditions are at their most intense and variable,” the company said in the earlier statement. “The suspect cause of the mortalities is a precipitous drop in dissolved oxygen.”

As Mowi cleans up dead salmon, fat blobs and decaying tissue bob on the water's surface. Photo courtesy Bill Bryden

Mowi said further study was underway to determine the cause of the low dissolved oxygen numbers and to “develop further mitigation strategies to prevent recurrence”. It noted that the company has “invested in deep netting and aeration equipment, which helped protect the fish and improve survivability through the event”.

Mowi advised Tuesday that “all available resources [have been brought to the] site to mitigate and address the situation”, adding that 212,100 dead salmon have been removed.

Undercurrent News reported in April how the Atlantic salmon industry was still dealing with a high rate of mortalities in NL following a massive 2.6 million salmon die-off that happened to Mowi there in August 2019. The event cost Mowi $5.5m in damages (after insurance claims were paid) and led to mountains of criticism and negative press, the temporary suspension of cage licenses, months of clean up, the rollout of expensive new technology, the replacement of an area manager, and the province’s issuing of no less than a dozen new aquaculture-related regulations.

Even more, it raised concerns about the sustainability of NL’s salmon industry, which finished 2019 with a total of 4.5m mortalities — 34% of the province’s original 13.3m salmon population – a loss of roughly one out of every three fish kept in cages across 27 total active farming sites.

In 2020, NL’s Atlantic salmon net-pen industry lost l.5m of the fish it kept in 21 aquaculture sites (six fewer than in 2019), which the NL Department of Fisheries, Forestry and Agriculture reported to be a mortality rate of 20% — one in five salmon – plus or minus 5%.