Norwegian researchers sound alarm bell on high sealice levels
Undercurrent News: June 26, 2014
Norwegian researchers have sounded the alarm bell on what they describe as extreme sealice infection levels in areas with high aquaculture activity alongside the southwestern Norwegian coast from Rogaland to Nord Trondelag.
Results from a new survey on wild salmonids in May and early June showed that nearly all wild sea trout in the area were seriously affected by lice.
As many as 50 to 100 lice per fish were found on large parts of the fish surveyed in the region, with as many as several hundred lice on some.
In a letter to the Norwegian Food Safety Authority, the Institute of Marine Research (IMR) warned the situation could rapidly become grave not just for wild sea trout but also for farmed fish.
“In those areas [Rogaland to Nord Trondelag], we found 50 to 100 lice on large numbers of the fish surveyed, and we found fish with several hundred lice in Rogaland, Hordaland and More og Romsdal,” said said Pal Arne Bjorn, project leader of the national sea lice monitoring.
The findings are worrying and mean farmers must be on higher alert and better equipped in the future, said NFSA department director Friede Andersen.
“All farmers need to carefully monitor their farms and should consider examining more pens and fish than what the minimum rules require. Not least, they must be ready to carry out measures on short notice,” said Andersen.
Sealice is the biggest challenge facing Norwegian salmon farms, and was identified recently by analysts as the biggest drawback to farmers’ valuation
Current regulations say farms cannot have more than 0.5 adult female sealice per fish on average in their pens. In a new proposal to expand current farm limits by 5%, the government applied as a condition that this would only be granted to farms that can keep the average to under 0.1.
Earlier this year, authorities warned they would increase monitoring and control of sea lice levels in farms.
Map of Norway. Extreme lice pressure has been observed along the coast from Rogaland to Nord Trondelag, said the researchers
The lice reproduce fast when sea temperatures are high. The temperature in June off the western Norwegian coast averaged 10-12 degrees Celcius, and has risen to 12.5 now.
“This means the lice that has made its ways into farms the past two to three weeks could develop into adult female lice already in the course of the next few weeks. Sea lice levels could rise significantly if farmers don’t manage to keep levels down,” said Andersen.
The first results from preliminary reports on sealice levels on wild salmonids along the coasts arrived last week, said IMR. These showed that much of the salmon smolt probably made it to the sea before the sealice situation worsened. Despite this, researchers fear that wild sea trout are in for a tough summer.
“The way the situation is now, we expect seriously negative impacts on the seatrout population over large geographical areas,” said Bjorn.
Particularly problematic is that the lice on the infected fish are dominated by young lice — copepodites and small larvae that have just attached themselves onto the fish.
This means that many levels of sealice infection are now at sea, said Bjorn. These lice are on the lookout for fish to attach themselves to, which again increases the contagion pressure over large geographical areas.
“This will affect the sea trout badly, but will also affect the aquaculture industry in the coming days and weeks.”
The observations on sea trout confirm prediction models developed by researchers based on the release of sea lice larvae from fish farms. These showed extremely high discharge levels of larvae from western Norway and Trondelag in May and early June 2014.