The effect of chemical anti sea lice treatment on hypothalamic–pituitary–Interrenal (HPI) Axis and its impact on animal welfare in Atlantic salmon post smolt (Salmo salar L.)
During a production cycle of Atlantic salmon from juvenile to slaughter the animal undergoes many critical production phases, which could elicit both grave stress responses and have major impact on animal welfare. One major stressor that have not been thoroughly documented is chemical anti sea lice treatment and its effect on primary, secondary and tertiary stress responses (Nolan et al., 1999).
The purpose of this study is to compare the response of the hypothalamic–pituitary–Interrenal (HPI) Axis subjected to three different chemical anti sea lice treatment in Atlantic salmon post smolts (Salmo salar L.). The following three hypotheses are proposed to be tested:
1. There are no differences in adrenocorticotropic hormone (ACTH) sensitivity during anti sea lice treatment regardless of chemical substance.
2. There are no differences in the negative feedback system of the HPI axis during anti sea lice treatment regardless of chemical substance.
3. There are no differences in the primary (plasma cortisol), secondary (osmolality, chloride and magnesium) and tertiary stress responses (SGR, mortality) during anti sea lice treatment regardless of chemical substance.
Approximately 800 Atlantic salmon post smolts will be divided in four tanks (1 m3) supplied with 50 m seawater (34 ppt). The experiment will consist of four groups (170 fish per tank). Group 1. Control no chemical treatment; Group 2. H2O2 treatment; Group 3. Salmosan (Azametifos) and group 4. Combination treatment AlphaMax (deltametrin) and Salmosan (Azametifos).
After chemical treatment (procedures, duration and dosage after recommendation from the suppliers of the anti-sea lice treatment) the fish will be moved to ten isolated 0,5 m3 tanks adapted to stress studies. Six fish per tank. To ensure maximum control of the experiment one experimental group at the time will be done per 72 hours. To determine the effect of different treatments on primary (plasma cortisol) and secondary (plasma chloride and magnesium) stress responses, blood samples will be obtained prior to start of the experiment (pre-stress), and 0,5, 1, 2, 3, 4, 6 12, 24, 48, 72 hours after the applied stressor. The fish will be rapidly transferred to a bucket containing a metomidate solution of 5 mg/L. This concentration which has shown to be sufficient in inducing rapid anaesthesia and preventing an increase in blood plasma cortisol (Iversen et al. 2003; Olsen et al. 1995). After being killed with a blow to the head, blood from six smolts (per group) at each sampling time will obtained from the caudal vein complex using size 0.50-x16-mm heparinised syringes. The blood will then be centrifuged at 5000 rpm for 5 min. and plasma will be removed and stored in cryo tubes at -36 oC until analyses are performed.
The purpose of this study is to compare the response of the hypothalamic–pituitary–Interrenal (HPI) Axis subjected to three different chemical anti sea lice treatment in Atlantic salmon post smolts (Salmo salar L.). The following three hypotheses are proposed to be tested:
1. There are no differences in adrenocorticotropic hormone (ACTH) sensitivity during anti sea lice treatment regardless of chemical substance.
2. There are no differences in the negative feedback system of the HPI axis during anti sea lice treatment regardless of chemical substance.
3. There are no differences in the primary (plasma cortisol), secondary (osmolality, chloride and magnesium) and tertiary stress responses (SGR, mortality) during anti sea lice treatment regardless of chemical substance.
Approximately 800 Atlantic salmon post smolts will be divided in four tanks (1 m3) supplied with 50 m seawater (34 ppt). The experiment will consist of four groups (170 fish per tank). Group 1. Control no chemical treatment; Group 2. H2O2 treatment; Group 3. Salmosan (Azametifos) and group 4. Combination treatment AlphaMax (deltametrin) and Salmosan (Azametifos).
After chemical treatment (procedures, duration and dosage after recommendation from the suppliers of the anti-sea lice treatment) the fish will be moved to ten isolated 0,5 m3 tanks adapted to stress studies. Six fish per tank. To ensure maximum control of the experiment one experimental group at the time will be done per 72 hours. To determine the effect of different treatments on primary (plasma cortisol) and secondary (plasma chloride and magnesium) stress responses, blood samples will be obtained prior to start of the experiment (pre-stress), and 0,5, 1, 2, 3, 4, 6 12, 24, 48, 72 hours after the applied stressor. The fish will be rapidly transferred to a bucket containing a metomidate solution of 5 mg/L. This concentration which has shown to be sufficient in inducing rapid anaesthesia and preventing an increase in blood plasma cortisol (Iversen et al. 2003; Olsen et al. 1995). After being killed with a blow to the head, blood from six smolts (per group) at each sampling time will obtained from the caudal vein complex using size 0.50-x16-mm heparinised syringes. The blood will then be centrifuged at 5000 rpm for 5 min. and plasma will be removed and stored in cryo tubes at -36 oC until analyses are performed.