The digestion time for salmon louse (Lepeophtheirus salmonis) in lumpfish (Cyclopterus lumpus)

• Published in: Aquaculture Vol. 578; p. 740103
• Main Authors: Staven, Fredrik R., Engebretsen, Solveig, Aldrin, Magne, Iversen, Nina S., Staven, Andreas R., Egeland, Torvald, Stensby-Skjærvik, Silje, Imsland, Albert K.D., Boissonnot, Lauris
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15-01-2024
• Subjects: Atlantic salmon; Cleaner fish; Digestion time; Lumpfish; Salmon lice; Lumpfish; Digestion time; Cleaner fish; Atlantic salmon; Salmon lice
• ISSN: 0044-8486; 1873-5622
• DOI: 10.1016/j.aquaculture.2023.740103

Atlantic salmon aquaculture employs lumpfish as a control method to combat ectoparasites, given their unique cleaning behaviour. There are multiple studies which estimate the average number of salmon lice in the stomach contents of dissected lumpfish. However, these numbers cannot be used to assess the cleaning efficacy of lumpfish (e.g., the average number of lice consumed daily per lumpfish) without knowing the digestion time of lice in lumpfish. The aim of the study was to provide quantitative estimates of the degradation of salmon lice, through a blinded clinical study over a duration of seven days. Individually tagged lumpfish (45.8 g, SD ± 10.28) were randomly arranged in triplicate tanks (n = 28 per tank) and acclimatised for three days. Subsequently, lumpfish were fed using oral gavage dosing with counts of lice (0–6), feed pellets (0–6) or a combination of both. Lice used were recently captured and stored at −80 °C to prevent parasite transmission at the study location and photographed before and after digestion to estimate degradation. Samplings ranged from 6 h intervals during the first two days, to 24 h and eventually 48 h for the last two days. Analysis of salmon lice revealed an expected digestion time of 29 h while the median digestion time was estimated to 15 h at 9 °C. Pellets dissolved quickly and had no impact on the lice digestion time. The findings of this study can be used to estimate cleaning efficacy of lumpfish from stomach contents of salmon lice.
•Digestion time of salmon lice was studied for tube-fed lumpfish held at 9C°.•After 14.6 h, we estimated that only 50% of the salmon lice were visually detected.•The estimated average digestion time was 29 h.•Lice transparency over time increased similarly to the decrease in fed lice recovered.