Forsøksdyr: Trout experiment to develop P and B data on petroleum substances

Godkjenningsdato 01.09.2020

Godkjenningsperiode 01.09.2020-31.10.2020

Purpose: The aim of the proposed study is to generate empirical datasets to validate the application of two-dimensional gas chromatography (GCxGC) for determining the persistence (P) and bioaccumulation (B) for groups of petroleum substances in fish (brown trout, Salmo trutta) tissue. To achieve this we propose a bioaccumulation study using juvenile brown trout and two middle distillate oils alongside a control group. We will analyse a time-series of extracts from fish fed on hydrocarbon spiked feeds using GCxGC.
1. Distress: We do not expect any distress of the fish regarding the treatments. Fish will be kept in state-of-the-art tanks, supplied with fresh water at all times and fed high quality diets. The 'treatment' group will receive feeds spiked with 2 different types of middle distillate oils, which we do not expect to harm the fish. The exposure will be two weeks to ensure enough build up of hydrocarbons in muscle tissue to be detectable by GCxGX and will be followed by a 4 weeks period of feeding on non-spiked commercial trout diets. We will tag the fish to investigate individual growth rates, which has to be considered as a moderate stress for the fish.
2. Expected benefit: Data from this study will be used to develop and refine models on fish organismal response to oil contamination. These models can help to evaluate the severity and long terms effects of e.g. oil spills and help in risk assessments.
3. Number of animals, and what kind: Juvenile brown trout (Salmo trutta), ca. 10g wet weight. We will use 600 fish. We choose trout, as salmonids are a typical model species and a lot of knowledge on e.g. physiology is already available. There is also a large body of data on oil and trout available, and we'd like to add to that.
4. How to adhere to 3R: Replacement: Since we are studying bioaccumulation and biodegradation in fish, we need to work on whole organism and cannot replace the study organism (here: trout) by e.g. tissue cultures or non-vertebrate animals. Reduction: The experimental design is set up in a way to use minimum amount of fish to produce enough biomass to be able to analyse the various hydrocarbons, an gather robust information in terms of expected variability. Refinement: We will not apply distress to the fish during the exposure. The tagging indeed poses a distress. We will use tiny T-bar tags to individually mark fish, which is the least harmful tag possible in this application. If we would not tag the fish and follow individual growth rate we would have to se way more fish to smooth out individual variability in growth rates (in fish biology, typically it would be around 10 times the amount of fish).