Biofluorescent response in lumpfish Cyclopterus lumpus to a therapeutic procedure as assessed by hyperspectral imaging

Abstract

Abstract The demand for lumpfish (Cyclopterus lumpus) as a biological control for salmon lice is increasing. However, lumpfish welfare is considered a limiting factor within aquaculture operations. Identifying a noninvasive parameter that measures subclinical stress in lumpfish is a key goal for improving their welfare. The lumpfish is amongst many marine species documented to biofluoresce within the blue shifted light of their environment. Lumpfish (n = 80) underwent a 3-hour freshwater bath therapeutant to evaluate whether fluorescence spectra produced by the species responds to external stimuli. Lumpfish were quickly scanned under a hyperspectral camera (400–1000 nm spectral range) prior to and after treatment. Here we show that lumpfish fluorescence responds to freshwater exposure within a controlled experiment. All three experimental groups increased their fluorescence in response to treatment, though the level of change depended on whether the averaged, red, or green spectra was analyzed; the control group remained consistent. The mean emission spectra differ between groups, particularly between 690 to 750 nm. All lumpfish emit green fluorescence while a segment (49%) produced red fluorescence. As lumpfish fluorescence shifts in response to the applied therapeutant, this study provides insight into how fluorescence may be incorporated into the welfare management of an aquatic species.