Introduction . Lumpfish, Cyclopterus lumpus, is in some regions used as cleanerfish in aquaculture pens with salmon Salmo salar L. farming to reduce the infestation of salmon lice. In the Faroe Islands, lumpfish have for some years been used as cleanerfish by the aquaculture industry with relatively good results. However, there have in some cases been a high mortality rate for the lumpfish in the pens and a great deal of effort is currently being put towards improving their welfare. In this context, the project “Lumpfish & Akva-Nest” investigates the effect of plastic versus seaweed shelters on the welfare of lumpfish in aquaculture pens and the potential implications for their effectiveness as cleaner fish.
Figure 1. Heat-tree comparison of bacterial compositions in skin samples from lumpfish in pens with plastic shelters and seaweed shelters
Methods . The project setup was located on an aquaculture facility and included six pens with salmon and lumpfish. Three of the pens had plastic shelters for the lumpfish and the other three had seaweed shelters. Sampling was performed for all sample types shortly after the lumpfish were deployed in spring 2023 and on two more occasions with about five weeks intervals. Samples for microbial sequencing were taken of the shelters in triplicates and from skin and gills of 10 lumpfish from each of the six pens. Welfare parameters of the lumpfish were also registered at each sampling. DNA extraction and library preparation was performed at Firum lab and sequencing at Novo gene. Bioinformatic analyses were performed in Qiime2 and R.
Results . The analyses of the bacterial communities showed the presence of several potentially pathogenic genera. Comparisons between lumpfish in pens with seaweed and plastic shelters and the shelters themselves revealed various differences in the relative amounts of some of these bacteria (Fig 1). However, there was not a straight forward relationship between the presence of these bacteria in the shelters and the lumpfish skin.