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

Stage IV and adult lobsters (Homarus americanus) were exposed repeatedly to one of two pesticide formulations currently in use as anti-sea lice treatm ents: Salmosan(R) (azamethiphos) and Excis(R). (cypermethrin). Stage IV lob sters were affected by these exposures only at the highest concentrations a nd longest exposure periods but no deaths occurred. Exposure to concentrati ons 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 lobste rs. Adult lobsters exposed to Excis(R) were affected over a wider range of concentrations and exposure times than those exposed to Salmonsan(R). The N o Observed Effect Concentration (NOEC) for azamethiphos and adult lobsters is 1.03 mu g/l (as azamethiphos) when exposed repeatedly for 120 min. The N OEC for Excis(R) is 0.025 mu g/l (as cypermethrin) when exposed repeatedly for 60 min. (C) 2000 Elsevier Science B.V. All rights reserved.