Quantifying the potential of skin swabbing as a refinement for DNA sampling of laboratory fish

Fin clipping under non-terminal anaesthesia is the SOP for sampling DNA from fish in lab studies. However, fin clipping causes pain and induces stress in fish, and the use of anaesthesia potentially impacts data quality. Globally, we estimate ca. 1M fish are fin-clipped each year. The recent development of skin swabbing techniques - which produce sufficient DNA for PCR amplification - potentially offers a refined procedure with enormous impact for fish welfare. Our group has recently developed such a technique for zebrafish that has been well received by the community. However, as swabbing still requires fish to be netted, air-exposed and restrained, the magnitude of any actual welfare benefits over fin clipping remain unquantified, and the value of swabbing as a refinement untested.

Our main aim is to test the hypothesis that swabbing has a significantly lower impact on stress-related behaviour and physiology than fin clipping, and so represents a valid
refinement to current regulated procedures. We propose a series of experimental studies comparing the effects of swabbing and fin clipping on a range of indicators of stress and wellbeing. To demonstrate the potential for cross-species benefits, we will study both zebrafish and sticklebacks. We will expose fish to a range of control, swabbing or fin clipping treatments, designed to separate the effects of various components involved in each procedure, and quantify behavioural and physiological correlates of stress over appropriate timescales. We will additionally compare the effects of analgesia on the stress responses of fish subjected to swabbing and fin clipping, to investigate the relative pain associated with each approach. Finally, we will examine the potential of proprietary water treatments to provide further refinement to swabbing procedures. We will publicise our results to a wide network of end users to ensure that our recommendations are taken up by the community.

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