Sea lice-eating lumpfish: focus on shy-bold axis behavior and molecular expression

Sea-lice (Lepeophtheirus salmonis) is a major bottleneck for Atlantic salmon (Salmo salar) aquaculture growth. Several strategies to control sea-lice are used nowadays, including sea-lice fish eaters. This last strategy is promising as it is the one with a lower stress and welfare impacts on Atlantic salmon and the environment around the sea cages. However, the use of sea-lice eater fish also poses challenges. For instance, a given lumpfish (Cyclopterus lumpus) population has a high variation on sea-lice eaters individuals, being estimated that only a low percentage do eat sea-lice. This has the impact of stocking in sea cages millions of lumpfish that will not eat sea-lice thus, a high economical cost and a high animal use with large implications on animal use ethics and welfare. However, the sea-lice eating decision may be related with individual behavioral traits. This is, the choice to eat a sea-lice could be a consequence of a bold-shy reaction to a perceived risky situation such as swimming towards a much larger fish in motion and prey the sea-lice. Therefore, this project aims to study the relation between the shy-bold axis behavior and the sea-lice consumption, and to understand if this has a differential molecular expression background. Lumpfish juveniles will be subjected to an initial behavior test to screen and categorize individual fish into bold or shy. The bold and shy fish will be pit-tagged and transferred to a sea cage with infected sea-lice Atlantic salmon. Three weeks later, lumpfish will be sampled, weighted, stomach content empty and the number of sea-lice count. Tissue samples will be taken for further molecular analysis to relate boldness with molecular expression differences. The results from this study will be important to develop strategies for a better selection of lumpfish prior to sea cage stocking. Ultimately, this information may contribute to the use of fish more eager to eat sea-lice and, therefore to the reduction of lumpfish stocked in sea-cages while maintaining the same sea-lice control.