More farmed salmon died in Norway's cages last year than the year prior, the result of an acute algal bloom attack in the Northern part of the country last summer and continuing challenges with sealice management.

The annual "Fish Health Report" calculated over 52.8 million farmed salmon died in Norway last year. While the figure is significant -- and costly -- the underlying trend was a positive one when taking out the losses of the algal bloom, which reached 8 million fish.

While mitigating algae blooms are a critical part of farm management, the losses were unrelated to the overall health of the sector, Ingunn Sommerset, fish health officer at Norway's Veterinary Institute, told IntraFish.

Counties such as Hordaland have reduced salmon mortality by around 25 percent in two years, showing the industry is making improvements on fish welfare, Sommerset said.

But despite some improvements, the biggest bane of the sector continued to cause losses, so much so that the year could be dubbed "the year of the sealice," the institute said.

As in previous years, the damage caused by sealice treatments was the largest health challenge for producers in Norway, a trend also evident in a survey of fish health professionals and industry, Sommerset said.

The number of non-drug sealice treatments increased to 2,446 from 2,002 treatments in 2018, while medicinal treatments also increased: to 698 treatments in 2019, compared with 602 the year prior.

Sommerset noted that treatments have gone down, with 2014 the peak at 3,498, in part from novel treatments, but in part from sealice developing resistance to certain chemical methods.

Salmon

Over 50 million farmed salmon died in Norway last year as sealice, algal blooms take heavy toll