The lethality of anti-sea lice formulations Salmosan® (Azamethiphos) and Excis® (Cypermethrin) to stage IV and adult lobsters ( Homarus americanus) during repeated short-term exposures

Abstract

Stage IV and adult lobsters ( Homarus americanus) were exposed repeatedly to one of two pesticide formulations currently in use as anti-sea lice treatments: Salmosan® (azamethiphos) and Excis® (cypermethrin). Stage IV lobsters were affected by these exposures only at the highest concentrations and longest exposure periods but no deaths occurred. Exposure to concentrations equivalent to 10 or 25% of that recommended for sea lice treatment for periods of 15 or 30 min resulted in significant mortalities in adult lobsters. Adult lobsters exposed to Excis® were affected over a wider range of concentrations and exposure times than those exposed to Salmonsan®. The No Observed Effect Concentration (NOEC) for azamethiphos and adult lobsters is 1.03 μg/l (as azamethiphos) when exposed repeatedly for 120 min. The NOEC for Excis® is 0.025 μg/l (as cypermethrin) when exposed repeatedly for 60 min.