Forsøksdyr: Production strategy effects on the robustness of farmed Atlantic salmon smolt


Godkjenningsdato 30.11.2020

Godkjenningsperiode 30.11.2020-28.02.2023

Purpose
The timing of smoltification (parr-smolt transformation) and release in the sea is crucial and have a huge effect on the subsequent smolt seawater performance and losses. At present, the established way to produce fast growing fish during the juvenile stage involves selection of elevated temperature and continuous light regime which improve appetite and growth. Fish held at lower temperature and natural photoperiod (as in their natural habitat) would grow slower and require longer time to reach the proper size for smoltification. Salmon rearing conditions and timing /size may create changes in early life history traits affecting fish development (i.e. deformity development) and osmoregulation capacity, thus impairing robustness at sea. The first aim of the project is to investigate how diverse strategies to rear parr, i.e. fast and slow growth, and the size of the smolts at seawater transfer influence robustness in the seawater phase until harvest. In order to test our hypotheses, we aim to perform an experiment at the Matre Research Station at the Institute of Marine Research (IMR), on an ongoing production, where sibling fish has been divided in two groups: i) underyearling fast growing smolt (0+) under manipulated environmental conditions (higher temperature and continuous light); ii) yearling slow growing (1+) salmon under natural environmental conditions from the eye egg stage.
2 Harmful effects
The experiments are not expected to have serious harmful effects on the experimental animals. Although we are planning to Pit-tag 25g parr in order to study individual during the entire production.
3 Expected utility value
Results from such studies will increased the knowledge fundament for Atlantic salmon aquaculture production by providing clear cut answers of the impacts of recent breeding efforts and smolt production strategies. Increased robustness of smolts will by default promote their welfare and at the same time. In addition, the project aims to provide new knowledge of interest to the field of Atlantic salmon breeding biology, physiology and traits/markers connected with smolt robustness.
4 Number of animals and species
We apply to PIT-tag 850 25/30 g Atlantic salmon parr per/group (1700 total)
5 How to comply with 3R
Replacement: We cannot achieve the purpose of the experiments without using live A.salmon, and the experiments will use a total of 1700 salmon. Reduction: The number of experimental animals is based on previous knowledge from similar experiments conducted in the same experimental facilities, and the number of fish included in the sampling. We will use the lowest number of individuals who give valid results. As these are time-consuming experiments with expensive analyses, it is important that we achieve a high enough number of analyses per treatment that we can carry out robust statistical analyses, and do not have to repeat the experiments. Refinement: The experiments are not expected to have serious harmful effects on the experimental animals. To optimize fish welfare in the experiments, we will ensure good environmental conditions, monitor the fish's behavior daily, and remove and kill fish that show deviant behavior. The salmon will be fully anesthetized during tagging.