From Trash to Treasure: The use of Lumpfish (Cyclopterus lumpus) as feed for Red King Crab (Paralithodes camtschaticus)

Abstract

This thesis explores the potential of using farmed lumpfish (Cyclopterus lumpus), discarded from Atlantic salmon (Salmo salar L.) aquaculture industry, as a sustainable feed for juvenile red king crabs (Paralithodes camtschaticus). The red king crab has successfully established a self-sustaining population in the Barents Sea. With the red king crab being a large generalist predator, its impact on native bottom communities is a concern. Additionally, the red king crab fishery is a valuable resource, while the lumpfish is an important natural alternative for treating sea lice (Lepeophtheirus salmonis) in salmon aquaculture. The lumpfish stops eating lice when reaching sexual maturity, the fish is then discarded. The study involved feeding four different diets to juvenile red king crabs over 12 weeks, consisting of dry feed, dry feed coated with lumpfish hydrolysate, a combination of dry feed and fresh frozen lumpfish and fresh frozen lumpfish. The crabs receiving mixed diets was seen to have the highest feed intake. The results suggest that lumpfish can be used as feed, providing a basis for better utilization of the resource while reducing pressure on the ecosystem by removing juvenile king crabs from the sea. This approach would enable the harvesting of one resource, the utilization of a "by-product", and a reduction in negative impacts on the ecosystem. Ultimately, this research promotes sustainability and responsible resource management.