Money for nothing: The possible use of recycled fish farm material as habitat for lumpfish

The use of lumpfish in salmon farming allows the removal of sea lice all year round, without the use of chemicals or mechanical treatments. For cleanerfish to perform effectively, husbandry is key. Within the husbandry requirements is the placement of habitats in salmon cages, to allow the cleanerfish to rest and shelter. Habitats currently used can be costly, and require manual labour efforts to be removed from salmon pens to dry biofoulants, which could potentially be an unwanted food source for the cleanerfish. This study analysed preference of different materials from a recycled fish farm source (walkway, feed pipe, cut feed pipe, plastic sheet), to develop a cost effective, easy to use, lumpfish hide for sea pen deployment. Preference for different colours of the preferred substrate was subsequently investigated. Initially the juvenile lumpfish preferred the thin sheet of plastic over the recycled substrates, but towards the end of the trial there was no significant difference found between the plastic sheet and the recycled feed pipe tubes and walkway tubes. This indicates that it is possible to use low-cost, recycled material as substrate, and hides, for lumpfish in salmon farms. The colour trial indicated a clear preference for the colour black by lumpfish.