| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 2422714 | Aquaculture | 2012 | 7 Pages |
Ivermectin (Eqvalan®) (IVM) has been widely used as an oral treatment of sea lice (Lepeophtheirus salmonis Caligus sp.) infestations of farmed Atlantic salmon (Salmo salar L.). We report the use of a suite of behavioral, physiological (growth, liver somatic index, brain acetylcholinesterase (brain AChE) and vitellogenin (Vg)) responses to explore the effects of dietary doses of IVM on juvenile Atlantic salmon. Brain AChE was measured because of IVM's neurological activity and its ability to cross the blood–brain barrier. Induction of plasma Vg was used as a measure of IVM's possible estrogenicity. Fish were treated as follows every third day for 30 days: (a) low dose 0.05 mg kg− 1 body weight (bw), (b) high dose 0.25 mg kg− 1 bw, and (c) control (0 mg kg− 1 bw). After 30 days, half the fish from each tank were sampled. The remaining fish were held for 30 additional days on a clean diet to observe the potential for recovery. Cumulative mortalities of 5% and 70% were observed in the low dose and high dose IVM treatments respectively. Fish weight and condition factor were reduced after 30 days in the high dose IVM treatments (p < 0.05). Liver somatic index (LSI) was significantly reduced in the female fish treated with low dose IVM after 30 days of depuration (p < 0.05). Fish dosed with IVM had apparently reduced mobility and took longer to complete feeding. Male dosed fish had significantly higher brain AChE activity (p < 0.05). Plasma Vg was lower (p < 0.05) in the high dosed female fish after 30 days. Vg was also lower in the low dosed female fish (p < 0.05) after the depuration period. These results have importance for aquaculturists in the calculation of rations and therapeutic dosage strategies for the IVM treatment of sea lice infestations in Atlantic salmon.
► We report novel physiological observations due to ivermectin overdose in salmon. ► IVM affected fish growth, and fish weight/length were reduced after 30 day exposure. ► Hepatic somatic index (HSI) was significantly lower in IVM treated female fish. ► Male fish dosed with IVM had significantly higher brain AChE activity. ► Our findings could improve calculations of therapeutic dosages in Aquaculture.
