Forsøksdyr: Determination of the PAA exposure concentration and administration method without effect on Atlantic salmon parr (Salmo salar) health, welfare or growth.

Godkjenningsdato 22.06.2020

Godkjenningsperiode 15.09.2020-15.09.2021

1. Purpose
Land-based flow through systems are being replaced by recirculating aquaculture systems (RAS). RAS consist of a series of water treatment units, including a biofilter to treat the water and reuse it. However, the nature of RAS poses a new challenge on how to disinfect the water without producing an adverse impact on the salmon’s health and welfare, and biofilter performance.
Peracetic acid (PAA) as a water disinfectant is used in Denmark and is used as a strategy to control pathogens in rainbow trout RAS. This chemical can be applied continuously or intermittently (as pulses) to disinfect water. PAA is a highly reactive peroxygen compound that degrades in to oxygen and water, and has the potential to control bacterial and parasitic infections and has a wide-range of antimicrobial effects. In Norway PAA based products are used to disinfect surfaces and equipment in RAS facilities, but it is not yet applied as a water disinfectant. Preliminary results showed promising results for PAA use as a water disinfectant revealing that Atlantic salmon smolts can withstand a single and repeated exposure of relatively high PAA dosages with minimal physiological disturbances. However, parr may have different threshold of tolerance to PAA when compared to smolt, a larger and seawater adapted fish.
To consider the use of PAA as potential water disinfectant for commercial use in parr land-based culture, it is necessary to investigate the optimal PAA concentration and administration method for Atlantic salmon parr (Salmo salar) health, welfare and growth.

2. Distress
It is expected the fish to experience a mild to moderate distress due to PAA exposure on the high-end range concentrations. However, this should be minimally due a relatively low high dose and the step-by-step trial approach.

3. Expected benefit
The current project aims to provide relevant data on parr health, welfare and growth response to a range of PAA concentrations and two PAA administration methods. Ultimately, this information can contribute to an informed decision on whether and how to use PAA in commercial RAS.

4. Number of animals and what kind
Nine hundred (appr. 10 g) mix-sex Atlantic salmon (Salmo salar) parr are proposed to be used.

5. How to adhere to 3R
Replace: It is not possible as it is necessary to use live fish to estimate its response to PAA exposure. Reduction: The number of fish requested is a minimum replicated sample to give reliable scientific results. The experiment will be performed in small tank units, which reduces the number of fish need. Refinement: The step-by-step trial approach of this study aims to design the subsequent trial based on the previous trial information, specifically the PAA concentration to use. Moreover, fish will be held by experienced and qualified staff on Atlantic salmon handling and sampling. Humane end points are defined and, the experimental systems are design for optimal rearing conditions for Atlantic salmon.