Forsøksdyr: Characterization of environmental limits and stress response in cleaner fish for responsible use in salmon aquaculture

Godkjenningsdato 09.07.2018

The use of cleaner fish as a supplementary tool against sea lice in Atlantic salmon aquaculture has increased drastically in recent years. The most commonly used species in Norway are the lumpfish (Cyclopterus lumpus) and the ballan wrasse (Labrus bergylta).

If cleaner fish are to be used responsibly and ethically in salmonid aquaculture in the future, a systematic characterization of environmental thresholds are urgently needed. Morphologically and physiologically the lumpfish and the ballan wrasse are fundamentally different from Atlantic salmon, and have adapted different tolerances to environmental variability. Hence, environments where Atlantic salmon thrives may be detrimental for either species of cleaner fish. Accordingly, the aim was to find the environmental thresholds and preferences for lumpfish and ballan wrasse compared to Atlantic salmon. This will allow us to predict which farm locations are suitable for responsible use of cleaner fish.

The proposed experiments in this application will work in synergy with on-going studies on swimming capacity and metabolic rates of cleaner fish and Atlantic salmon acclimated to various environments. In this application, the focus will be on acute exposures to environmental extremes. Specifically, we want to measure the critical temperature (Tcrit), the critical oxygen tension (Pcrit), acute salinity tolerance, and haematological effects on acute handling stress and hypoxia in the lumpfish and the ballan wrasse. In addition, we will perform some of these measurements on Atlantic salmon as well so that a proper comparison from similar experimental conditions can be made.

The methods we plan to use are well-established, and are commonly used in many sub-disciplines within fish biology to study evolutionary adaptation, phenotypic plasticity, response to environmental change, effects of toxicants etc. These methods are non-invasive and duration of potential discomfort is very brief.

All proposed experiments will be performed at The Institute of Marine Research in Matre, Norway. Experiments will be performed by trained researchers with expertise in comparative physiology and fish biology. We wish to start the experiments in June 2018 and expect to have finished all trials by June 2019.

Considering the 3R's and based on previous experience in obtaining necessary statistical power in the data, as well as to meet the standards required for publication in scientific journals, we require 12-15 replicate animals per treatment group. We are going to use 93 lumpfish, 168 ballan wrasse, and 36 Atlantic salmon.

Refinement and reduction has been carried out to maximum potential. Knowledge obtained in these proposed experiments cannot be obtained in an alternative way without the use of experimental animals.