Forsøksdyr: Sea lice feeding behavior and domestication background in lumpfish

Godkjenningsdato 02.09.2020

Godkjenningsperiode 11.09.2020-23.01.2021

In this study we will investigate possible correlations between genetic diversity, feeding behaviour and number of sea lice eaten by lumpfish juveniles with different domestication backgrounds. The study is conducted on wild and F1 progeny of lumpfish. The experiments are conducted at the Fish Health Laboratory (FHL) of the Tromsø Aquaculture Research Station at Kårvika (TARS). The wild sample was collected during summer in Tromsø near TARS and the first-generation (F1) offspring was obtained from AkvaPlan-NIVA at Kraknes in Tromsø. All fish were transported in tanks equipped to ensure the health of the fish during the transportation to TARS where they were acclimated in separate tanks at 10 °C. All individuals were anesthetized with benzocaine (100 mg/L), weighted and measured before they were individually PIT-tagged (passive integrated transponder) and marked with elastomer (VIE) tags. As the colour of the VIE tag was not possible to be visualized by the video monitoring system, each group of fish was tagged with an additional colour tag; FPN in the case of the hatchery fish and fine anchored TBF tags in the wild fish. After the acclimation period, 15 lumpfish juveniles from each domestication background (45 in total) were placed together with 30 salmon of approximately 300 g infested at 12 sea lice per fish density in a 500 l tank over a two months period. This experiment will be conducted in 2 replicates, placing the same number of individuals in another 500 l tank and running the experiment simultaneously. Fish feeding activity on sea lice will be determined by an automated video analysis and a gut content analysis. During the automatic video analysis, we will monitor feeding behaviour of each identified lumpfish on an individual salmon. For the gut content analysis, every two weeks, 10 individuals from each of the groups will be sampled from each of the two common tanks, identified by scanning its PIT-tag, measured, weighted and a gastric lavage will be performed to determine the number of sea lice eaten before returning the fish to the common tanks. The same individuals will be sampled over the two months experimental period. At the end of the experiment, the fish will be euthanized, and a DNA and RNA sample collected and stored on RNAlater for posterior DNA and RNA analysis. This study will assist to understand the genetic basis explaining good appetite for sea lice and contribute to produce robust juveniles displaying good sea lice eating performance for deployment into salmon net pens.
We have taken into account the available information regarding fish transportation, tagging methods, rearing techniques, feeding behaviour as well as fish health and welfare considerations in order to minimize stress or suffering of the fish, and improve the welfare conditions. The fish will be maintained under common salmon farming conditions and exposed to relatively low levels of distress; therefore, overall mortality rates at the end of the experiments are expected to remain below 20 %. Based on our estimations to adhere to 3R, we consider that 50 fish per domestication background is the minimum number of fish necessary to perform this type of studies and obtain meaningful results.