THE LETHALITY OF IVERMECTIN, A POTENTIAL AGENT FOR TREATMENT OF SALMONIDS AGAINST SEA LICE, TO THE SHRIMP CRANGON-SEPTEMSPINOSA

Ivermectin is an anti-parasitic drug effective against a wide variety of parasites. Ivermectin has been shown to be effective against the sea lice Lepeophtheirus salmonis and Caligus elongatus. The shrimp Crangon septemspinosa was exposed to ivermectin in water and via treated salmon food. Shrimp seemed unaffected when exposed to ivermectin in water (maximum concentration = 21.5 mug/l nominal). However, when ivermectin was present in salmon food, it was lethal to the shrimp (nominal 96 h LC50 = 8.5 mug ivermectin Per gram of food). The NOEC was approximately 2.6 mug/g. These results suggest that ivermectin, when used at the above concentrations, may present a hazard to non-target organisms during or after oral treatment of fish against parasites.