Havforskningsinstituttet Ruse og Garn NALO 2021

• Main Author: Nilsen, Rune
• Format: Dataset
• Language: unknown
• Published: Institute of Marine Research 2021
• Subjects: Arctic; Barlaup; Garn; Arctic charr
• Online Access: https://dx.doi.org/10.21335/nmdc-913438757; http://metadata.nmdc.no/metadata-api/landingpage/2fdddaa478c15b36516a2150bce243b9

Sea trout and/or Arctic charr were sampled within each locality with either modified floating traps or floating gillnets. The floating traps have been successfully used for monitoring sea lice on salmonids since approximately 2010. Some variation of the trap exists, but in general it consists of a dense 5 meter deep leading-net fixed to the shore, who leads out to a floating funnel trap with a few chambers. The most common model is described in detail by Barlaup et al. 2013* . The gillnets, exclusively monofilament, vary in mesh size from 17-26 mm between knots. Gillnets are deployed 90 degrees from shoreline in suitable locations. Length and height of the gillnets are respectively 30 and 2,5 m. Traps are checked minimum every day. Gillnets are checked continuously while deployed. Lice counts on sea trout were performed in the field immediately after collection. Fish from traps were anesthetized before sampling (Benzocaine 200 mg/ml diluted by 15-20 ml/100 l water) and released to the sea after recovery. Trout from gillnets were killed. Lice counts were performed with the fish submerged in a white plastic tub (5-10 l) using a strong headlamp (>500 lumen). Counts were performed by personnel with special training in identification of all salmon lice stages. The following 6 lice categories was recorded: copepodite, chalimus 1, chalimus 2, pre-adult, adult male and adult female. Fish length in mm and mass in gram were recorded.