Vince McDonagh

BY VINCE MCDONAGH

Heated argument

Thermal cleansing is intended to rid fi sh of lice, but some argue it brings its own problems

An intense debate is currently underway in Norway over the prac� ce of using warm water to remove salmon lice.

Pitching environmentalists on one side and the industry on the other, it is an argument that could eventually impact on all northern hemisphere aquaculture businesses.

In recent years, hot water treatment – some� mes described as thermal cleansing – has overtaken chemical and mechanical methods as the most common method of de-licing fi sh. It is a prac� ce which has received par� al veterinary approval.

New studies, however, have suggested that using water above 28oC can cause salmon to show pain-related behaviour. Currently, salmon are exposed to temperatures between 29oC and 34oC for around 30 seconds.

The salmon louse is a � ny parasi� c crustacean – not so far distant from crabs or lobsters - that feeds on mucus, skin and � ssue fl uids on salmonids in the sea. Lice are also found on other fi sh.

Although naturally occurring in salmonids, they have increased hugely due to intensive farming methods, with fi sh concentrated in small areas and in larger numbers crea� ng an opportunity for the parasite popula� on to grow.

The claims around “thermal treatments” have led to inves� ga� ons (and accusa� ons) on the part of a number of groups.

Toine Sannes, a leading Norwegian Green Party environmentalist, claimed recently that the prac� ce led to salmon being scalded at � mes.

This led to a sharp response from Seafood Norway, the employers’ organisa� on which represents both aquaculture and sea fi shing companies. Wri� ng in the journal and website Kyst og Fjord (Coast and Fjord), Karoline Skaar Amthor, Seafood Norway’s head of environment and health and the organisa� on’s communica� ons director Kris� n Langeland, both fi rmly rejected the allega� ons.

They said: “All available research shows that this is wrong. Nowhere has it been shown that an exposure of fi sh for 30 seconds with water up to 34oC causes scalding and burns.

“What we see is an escape response in the fi sh as a result of the warm water. It must be handled so that the fi sh does not injure itself during the short exposure � me. Risk reduc� on thus lies largely in planning, technical design and prac� cal implementa� on.”

They further added: “All handling of fi sh is to the detriment of the fi sh. It is an independent goal to safeguard fi sh welfare throughout the produc� on cycle. We use a number of welfare parameters to assess whether the handling is acceptable in rela� on to the purpose or not.”

Many industry experts with long experience in this area argue that it is mainly condi� ons other than water temperatures which cause fi sh welfare problems.

Figures from the Norwegian Veterinary Ins� tute show that the number of incidents of high mortality a� er thermal treatment has been declining.

Norwegian Seafood’s Amthor and Langeland maintain: “Mortality has not increased even though volumes have increased, on the contrary. We are gaining be� er knowledge about how to detect, diagnose and deal with disease-causing organisms more quickly through drawing lessons from one area of knowledge to the next. This has made Norway one of the world’s foremost and most successful seafood producers.”

“There has also been progress in terms of welfare and it will con� nue. Construc� ve cri� cism

Left: Toine Sannes Opposite from top: The Voe Viking will usually treat three pens a day; Karoline Skaar Amthor; Kris� n Langeland; Lice on a salmon

is a good thing, but characteris� cs such as ‘scalding of live fi sh’ do not contribute to anything posi� ve.”

However, the Norwegian Food Safety Authority has recently intervened, recommending cau� on on all sides. It said the use of non-drug treatments is one of the main factors in poor farmed fi sh welfare for Norway, adding that it and the industry both agree that things have to improve.

The Authority points out that certain current methods for trea� ng lice can be very stressful, adding that more than 20 million fi sh died before slaughter last year. While the reasons were complex, non-drug treatments were among the main causes.

It states: “The Norwegian Food Safety Authority will follow up on the consequences of lice treatment for fi sh.

“This means that it will be possible to use thermal treatment against salmon lice if the eff ect is good and the treatment is carried out in a responsible manner. The industry must con� nue its work both to improve the method to ensure sound fi sh welfare, and to map whether this method has the necessary eff ect on salmon lice.”

The statement goes on: “Preven� on is always more important than treatment. Good opera� on reduces the welfare challenges for the fi sh and reduces the need for lice treatment, including thermal de-lice. The authority’s CEO Ingunn Mid� un Godal said: “We see that some players succeed quite well with this [method] today. We expect the en� re industry to operate to the same high standard. This means more emphasis on preven� on against lice infesta� on, so that the need for treatment is reduced.” The debate has also been welcomed by the company Flatsetsund Engineering (FLS) which specialises in developing treatments that off er high fi sh welfare. Wri� ng on the industry website ilaks.no and posted on the company’s own website, the CEO Lars Georg Backer, challenged the authori� es to set be� er standards on documenta� on – “for the sake of the fi sh”.

He said many fi sh farmers wanted to use methods that provided improved welfare but it was diffi cult to compare methods and that is why FLS thought it “high � me” to put in place documenta� on requirements that provide knowledge about how the fi sh are doing both during and a� er the opera� ons.” FoMAS, an independent health service that off ers veterinary services to the aquaculture sector, has been carrying out its own studies. These indicate that at low sea temperatures it is possible to obtain the right results with water at 28oC when combined with rinsing. However, at high sea temperatures water at 29oC was required. FoMAS says the trials will con� nue this year. And so too will this passionate debate. And so too will this passionate debate. FF

“Preven� on is always more important than treatment”