Here's Compassion in World Farming's scientific assessment of the Thermolicer prepared by Phil Brooke (Scientific Manager - research and education):
Scientific Assessment by Compassion in World Farming (6 November 2016)
The Thermolicer appears to be a brutal treatment which has not been subjected to a full and proper welfare assessment. It involves a series of steps which are inherently stressful and will cause poor welfare to the fish.
- The salmon are crowded in a net
- They are pumped in water through a tube into a boat with the Thermolicer on board
- They are taken out of water – the dewaterer is a metal grid which lets the water through. They bounce along a metal grid into the treatment water
- They then pass into seawater heated to 30-34 degrees centigrade. Salmon would never normally experience sudden temperature changes like this
- Finally, they are pumped back into their seawater cage
Improved design and management could reduce this stress but cannot be expected to eliminate it.
Any treatment system should be subjected to properly conducted welfare analysis before its use is permitted.
We have seen one report from the Norwegian Veterinary Institute ("Thermal de-licing of salmonid fish - documentation of fish welfare and effect") which documented statistically significant increases in:
- snout injury following treatment. It is suggested that this should be caused by the effects of crowding the fish before pumping onto the Thermolicer vessel
- fin damage
- scale damage following treatment on one of the sites
- cataracts on one site 3 weeks after treatment
This study appears flawed:
- The sample sizes were small (40 fish in each test) and different individuals were sampled in before and after tests
- There were no controls – they did not compare fish which were treated with others left untreated
- There was no comparison with alternative treatments
- There was no analysis of behavioural responses to higher temperatures, essential for any proper evaluation of the welfare effects of this treatment
This report was conducted to meet the requirements of Norwegian law that all new methods and technical developments must be proven and documented in regard to fish welfare before they can be taken into general use. However, the report also states that there are no clear criteria for documentation of new technology in terms of fish welfare.
It may be that other research was also carried out, but this analysis should not have been considered adequate for this purpose.
Sea lice infestation is a serious welfare concern in farmed salmon (Ashley, 2006). Sea lice are small crustaceans that can weaken and kill affected fish by eating their flesh (Naylor & Burke, 2005). They feed on the blood and underlying tissues of their host, causing scale loss and skin lesions.
The large number of salmon contained in cages allows sea lice to multiply substantially. Wild salmon range over a wide area, thereby minimising the opportunity for sea lice to find hosts and then to multiply.
The proximity of several salmon farms in an area increases the opportunity for sea lice to multiply. The lice which breed on the salmon also spread to wild fish causing problems for both welfare and wild fish numbers.
Sea lice infestation should be controlled by improved management rather than relying on routine treatment. The numbers of salmon farmed in area should be limited to prevent build-up of lice. Year classes should be separated to prevent older salmon infecting younger ones. All the salmon farms in an area should be periodically and simultaneously fallowed to break the cycle.
All forms of treatment for sea lice cause problems:
- Removing salmon from their cages and treating them in baths of hydrogen peroxide or in Thermolicers which subject both salmon and lice to heat shock is highly stressful, sufficient often to cause substantial mortality
- In-feed treatments are likely to be more benign to the salmon, but can contaminate the environment affecting other marine invertebrates to which they are also toxic
- Capture or breeding of cleaner fish such as wrasse or lumpfish which eat the lice off the salmon comes with considerable welfare risk to these kind of fish.
Treatment should therefore only be required as a last resort. No treatment should be used which has not been subject to a thorough welfare analysis which includes effects of treatment on behavioural responses and physiological measures of welfare in addition to any effect on health, injuries or even mortality.
As far as we are aware, no thorough peer-reviewed analysis of the welfare impact of Thermolicer treatment is available. Until this has been carried out, Compassion in World Farming is opposed to any commercial use of this treatment.
Use of bath treatment such as hydrogen peroxide are also highly questionable. Hydrogen peroxide is a well-known irritant. Fish find it very stressful and its application can cause significant mortality.
Read more via:
- Press Release: 'Thermolicer' Back-Fires Killing 95,400 Farmed Salmon
- Sunday Herald: "Oops: fish farm firm kills 175,000 of its salmon by accident"