Salmon losses

Large salmon losses at Lewis fish farm

1 November 2019

Thousands of farmed salmon have died at Loch Erisort in Lewis due to health issues following warmer than usual sea temperatures.

Fish flourished in the milder conditions but so did harmful parasites.

Mowi, the UK’s largest fish farmer and an important Western Isles employer, is now harvesting surviving salmon in a bid to minimise losses.

A similar situation is being experienced at a number of the the firm’s other sites across the west coast, which has hit the company - previously known as Marine Harvest - by nearly £7.6 million .

Costs in the busy run up to Christmas are expected to increase due to lower quantities of fish and the more “challenging biological conditions.”

Temperatures in sea lochs where the farms are anchored - 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, the company says.

Ian Roberts, the firm’s communications’ director, said: “Unprecedented warm sea temperatures over the past few months and associated plankton has traumatised salmon gills, challenging salmon health.

“The extreme environmental conditions have also increased sea lice above acceptable levels.

“We have dedicated many resources at our Loch Erisort farm to ensure we quickly bring the situation under control, which includes harvesting fish immediately for market.”

Gideon Pringle, Mowi Scotland’s production director, said: “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 are providing fish with additional air bubbling where feasible.