Catch me if you can: How to recapture lumpfish using light as an attractant

Atle Foss,Albert K.D Imsland,Bjørn Roth,Ane V Nytrø

doi:10.1016/j.aquaeng.2020.102074

Atle Foss, Albert K.D Imsland + Show 2 more

Open Access

https://doi.org/10.1016/j.aquaeng.2020.102074

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Abstract

The use of lumpfish in salmon farming allows the removal of sea lice all year round, without the use of chemicals or mechanical treatments. In Norway alone, around 31 million lumpfish are currently put into sea pens whereas no efficient method to re-catch these fish once they no longer are efficient salmon lice grazers (from 300 g) exists. At present, collecting lumpfish in sea-cages is a labour- and time-consuming process and, if these fish are to be harvested, an efficient method for collecting lumpfish is urgently needed. In this study, we tested coloured light as an attractant to lure lumpfish into passive traps (pods). Three small-scale pilot experiments both demonstrated the highest re-capture rate when a blue light-source was used, whereas red and yellow light gave the lowest re-capture rate. A subsequent large-scale trial failed to demonstrate significant re-catch of lumpfish. It is concluded that although blue light clearly attracted lumpfish in laboratory trials, further studies are needed in order to exploit this attribute commercially.

Highlights

With a rising human population and a subsequent need for sustainable protein sources, aquaculture is becoming an increasingly important industry worldwide (Little et al, 2016)
Based on results from the first two pilot experiments, blue light was chosen for further testing where colour attraction was compared between LED-light and glowstick both with and without an additional blinking angle present (Fig. 4)
When testing different blue light sources it was evident that LED-lights outperformed glowsticks (χ12 > 4.2, P < 0.05, Fig. 4), whereas additional blinking angling baits had little effect (χ12 < 0.8, P > 0.35, Fig. 4)

Summary

Introduction

With a rising human population and a subsequent need for sustainable protein sources, aquaculture is becoming an increasingly important industry worldwide (Little et al, 2016). Driven by large profit margins, salmonid aquaculture is responsible for approximately 7% of fish production worldwide (Aaen et al, 2015). The salmon farming industry faces a plethora of challenges in maintaining the welfare of their stock throughout the sea-based phase. The use of cleanerfish as a biological grazing technique for sea lice removal has been a popular eradication method since 2010 (Brooker et al, 2018). The most commonly used cleanerfish in the salmon sector is lumpfish Cyclopterus lumpus which can target the parasite across all seasons (Imsland et al, 2014a,2018a; Eliasen et al, 2018; Powell et al, 2018)

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