34 SEPTEMBER • WORLD AQUACULTURE • WWW.WAS.ORG Wild Lumpfish as a Benchmark in Research The approach of using wild lumpfish as a reference in Faroese research is not limited to liver color and body condition. Other lumpfish studies have applied this method to improve knowledge of lumpfish welfare and husbandry. Research comparing wild and farmed lumpfish has also been used to assess differences in nutritional requirements, feeding behavior and natural shelters (Photo 4). These studies help refine feeding strategies and management practices in aquaculture. Seaweed Shelters Recent research in the project Lumpfish & AkvaNest (FHF Norwegian Seafood Research Fund project 901781) has explored the potential of using natural seaweed shelters to improve lumpfish welfare and cleaning efficiency. The study found that while the seaweed shelters did not significantly alter lumpfish activity or lice consumption rates, they did harbor fewer pathogenic bacteria compared to traditional plastic shelters. This suggests that natural seaweed habitats may provide a healthier environment for lumpfish, potentially reducing infection pressure and stress-related mortality. Feed and Feeding Behavior The natural feeding behavior of wild lumpfish also plays a critical role in their effectiveness as cleaner fish in aquaculture. Lumpfish are opportunistic feeders, adapting their diet to whatever is available in their environment. In the wild, young lumpfish primarily feed on small crustaceans in coastal habitats before migrating to open waters as they mature. A study by Eliasen et al. (2018) showed that in salmon cages, lumpfish exhibit similar opportunistic behavior, consuming not only sea lice but also formulated feed, biofouling organisms, and seasonally available zooplankton (Figure 5, Photo 5). This adaptability can be both beneficial and challenging—while it may allow lumpfish to adapt to life in salmon cages in varied conditions, it also means that their delousing efficiency can fluctuate depending on the availability of alternative food sources. A recent PhD study investigated nutritional deficits in lumpfish feeds by comparing wild and farmed populations, aiming to improve welfare and survival. The study revealed significant differences in lipid and protein levels between wild and farmed lumpfish, which directly impact their health and efficiency as cleaner fish. These findings contribute to the formulation of nutritionally optimized feeds tailored to the specific dietary needs of lumpfish, enhancing their robustness and effectiveness in aquaculture. Conclusion The use of wild lumpfish as a benchmark has significantly improved our understanding of lumpfish welfare and performance in aquaculture (Photo 6). Research on liver color, body condition, feeding behavior, and habitat preferences has highlighted the TOP LEFT, FIGURE 3. Length-weight relationships. From Østerø et al. (2024). BOTTOM LEFT, FIGURE 4. Proportional distribution of body condition categories based on a) Gutierrez Rabadan et al. (2021) and b) wild lumpfish model. From Østerø et al. (2024). RIGHT, FIGURE 5. Monthly variation in the average prevalence of empty stomachs and in the average prevalence of food types in the lumpfish stomachs. From Eliasen et al. (2018). The use of wild lumpfish as a benchmark has significantly improved our understanding of lumpfish welfare and performance in aquaculture... . As long as lumpfish remain non-domesticated, using wild lumpfish as a benchmark continues to be a valuable approach.
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