Forsøksdyr: Using light for sea lice sterilization

Godkjenningsdato 20.03.2018

The project's objective is to develop the scientific basis for completely new methods against sea lice which are preventative and require little or no handling of fish.
With a new technique, we will sterilize lice eggs by disrupting their DNA while they are still attached to female lice. Our aim is to reduce hatching success and make any copepodids that hatch unviable with a technique that requires no handling of fish. The concept is to deploy sterilizing lights in sea cages attached to standard light arrays that deliver multiple micro-doses of sterilizing light to the egg strings on female lice passing by on fish. Micro-doses are small enough to have no welfare effects for salmon, but cumulatively affect the small exposed eggs. Incoming wild plankton will be unharmed due to the minimal dose received while drifting through the pen.
Tank trials are imperative to determine a) the efficiency of sterilizing light on disrupting the development of eggstrings or sterility of individuals, b) what doses are appropriate to affect eggstrings but not non-target organisms, c) the impact of low-dose sterilizing light exposure on the welfare of salmon over time.
Part 1: Treatment and control eggstrings from a pilot trial will be used to infect 6 fish (x 12 tanks) where lice will grow until mature adults and their eggstrings collected to calculate hatching success.
Part 2: In large tanks, 200 salmon infested with lice (~5 lice per fish) will be exposed to repeated, short-term exposures of sterilizing light. There will be 3 treatment and 3 control tanks. At two time points, welfare will be assessed on 20 salmon using the SWIM model and 10 euthanised for more detailed eye and skin examination. At the same time, eggstrings will be taken from 6 attached females, incubated and checked for hatching success.
Part 3: The subsequent copepodids from these eggstrings will be introduced to 3 replicate tanks (10 fish per tank, total 36 tanks) in an infestation challenge, repeated for the two sample points in Part 2. These lice will be grown to the reproductive adult stage, and 1) the infestation and survival success of lice will be measured, and 2) the viability of their eggstrings determined. The latter activity will determine whether exposure to sterilizing light results in a sterile F1 generation.

The number of fish in Part 1 is the minimum in relation to the number of copepodids expected to be produced. Fish number in Part 2 is from calculated stocking density, and can be reduced if the fish used are larger than 200g. The number of fish in the small tanks in Part 3 is determined by the expected number of copepodids produced from Part 2, whereby the treatment females are expected to produce less viable copepodids than the controls. The treatments are not expected to incur suffering or high stress in fish, however behaviour and physical appearance of salmon will be monitored continuously to ensure no negative effects of light exposure or infestation.Total fish requested for the 3 parts:1642.