Warm temperatures challenge fish health
Warmer than average sea temperatures this year, beginning late winter to its peak in July, have provided challenges to salmon and lumpfish survival at several of Mowi’s salmon farms in Scotland.
A recent inspection of Mowi’s Bagh Dail nan Ceann farm by the Animal and Plant Health Agency (APHA) raised concern that lumpfish* health and welfare was not adequately managed during a month that saw the highest average sea temperatures.
On September 16th, 2019, APHA communicated to Mowi by letter that “You have not been able to show that adequate actions were taken in the period between 10/7/19 to the 12/08/19 in order to promote the welfare of the lumpfish under your responsibility. Not taking effective decision at earlier date has prolonged the period while the lumpfish still at the site have been in need to be protected from suffering and disease.”
Mowi staff have since met with APHA inspectors to discuss the agency’s concerns and to ensure fish welfare remains top priority for the company and its employees.
Warm sea temperatures – the second highest annual average recorded in the last decade – have aided in providing ideal growing conditions for harmful algal blooms and has exacerbated health challenges common to salmon.
“Unfortunately some farm locations have suffered higher than normal mortality rates over the past few weeks,” stated Gideon Pringle, Mowi Scotland’s production director. “Our farmers are devastated to have lost fish after spending months raising them at their farms, and are doing what they can to protect their fish from this prolonged change to their environment.”
To help alleviate fish stress from high water temperatures and associated reduced saturated oxygen, Mowi farmers have provided their fish additional air bubbling where feasible (see header photo), and are harvesting affected crops earlier than scheduled to reduce biomass or fallow (empty).
“Despite this challenge, the company still plans to harvest guided volumes and remains committed to its open seas site development program at locations best suited for our fish and the local environment.”
Mowi Scotland documents weekly salmon survival at all farms on their website, found at https://mowiscotland.co.uk/category/lice-mortality-reports/.
*Lumpfish (Cyclopterus lumpus) swim alongside farm-raised salmon to help clean a salmon’s skin of naturally occurring marine parasites.