Bonjour, cher landais ...
l'essence de clou de girofle utilisée en anesthésique ou sédatif est une voie très prométeuse : elle est très efficace, et surtout n'induit pas la présence de résidus toxiques pour l'alimentation humaine.
Quelques spécialités ont vu le jour depuis ces dernières années (Aqui-S ... ), et je dois dire, pour les avoir utilisés, remplissent parfaitement leur rôle.
Petit explicatif (en anglais) : http://www.aqui-s.com
A water dispersible liquid anaesthetic for fin fish, crustacea and shell fish. It is particularly useful for the rested harvesting of fish, but can also be used for most animal husbandry and transport applications. This product is presently registered in New Zealand and Australia with a nil withholding period.
AQUI-S can be mixed directly with water to form a stock solution which is then dispersed in the water column. Most applications require a concentration of between 15 and 20 mg/l in an immersion bath to achieve anaesthetisation. Lower doses can be used for light sedation. Higher doses can be used to achieve rapid response. Response to the anaesthetic depends on the species, the age, level of fatigue and condition of the animals and environmental factors. Well rested mature salmon (Salmo salar and Oncorhynchus tshawytscha) can take between 5 and 8 minutes of exposure at 17 mg/l of AQUI-S before showing signs of loss of equilibrium, and most husbandry practices can be carried out after 12 to 15 minutes exposure. However much shorter response times of approximately 2 to 5 minutes to produce handleable fish can be obtained by working with higher concentrations. Fish that are not rested often have a faster response to the anaesthetic. In commercial applications the concentration is adjusted to achieve the response time that matches the ability to handle the animals. Handling systems have been designed to handle up to 10 tonne/h of fish with treatment response times of 10 to 20 minutes.
The advantages of AQUI-S compared to other aquatic anaesthetics are as follows:
AQUI-S is approved in Australia and New Zealand with a nil withholding period and therefore it is the only aquatic anaesthetic that can be used for harvesting fish in those countries.
Fish have a fast recovery from AQUI-S.
AQUI-S is effective at low concentrations of 10 to 20 mg/L corresponding to active concentrations of 5 to 10 mg/L. Most other anaesthetics require at least three times and up to twenty times this concentration of active ingredient to be effective. Sedative effects and changes to behaviour can be detected at lower concentrations.
AQUI-S has a wide margin of safety when used at low concentrations. This means that fish can remain in the treatment water for relatively long periods of time without fear of mortalities.
AQUI-S can be diluted directly in water (seawater or freshwater). It does not require the use of hazardous solvents.
AQUI-S is cost effective to use for harvesting. Typical application costs for farmed salmon are 2 to 3 cents(US)/kg fish harvested.
AQUI-S is gentle and humane in action. Fish do not usually show any adverse response to the presence of AQUI-S at 20 mg/L and therefore they do not demonstrate struggling or avoidance reaction as with some other anaesthetics.