16 Sustainable Aquaculture
Krill is king: How a tiny crustacean can lead to big savings Krill meal supplementation in fish meal challenged diets fed to juvenile olive flounder resulted in savings per kg of fish produced. By Tibiabin Benitez-Santana
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or decades, the fish and shrimp aquaculture sector relied on fish meal and fish oil to nutritionally upgrade feed formulas to maximise growth and efficiency. However, the use of fish derived products is becoming highly scrutinised due to sustainability concerns, which have driven to the development of low- to no-fish meal aquafeeds. This paradigm shift left the industry asking the million-dollar question: how to ensure higher sustainability at equal nutritional quality and feed cost? What does the feed of the future look like – and is it affordable?
A ‘small’ solution to a big challenge
Replacing fish meal is the greatest challenge for the aquaculture production of carnivorous fish. How do we reduce or completely remove fish meal from diets of fish species without running into nutritional imbalances or ramping up feeding costs? The answer to this huge problem lies with a tiny crustacean. Produced from Antarctic krill (Euphausia superba), krill meal has a rich protein and amino acid nutritional profile, on par with that of fish. It includes high levels of long-chain polyunsaturated fatty acids, such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), feed attractants and astaxanthin, which stimulate fish feeding behaviour (Tharaka et al., 2020). Krill meal is, therefore, a powerful supplement to low fish meal diets. In addition, krill meal supplementation stabilises feed costs. This has been validated in recent studies addressing zootechnical performance and cost-benefit of krill meal supplementation in diets provided to the carnivorous fish species European seabass (Dicentrarchus labrax) and olive flounder (Paralichthys olivaceus) (Khosravi et al., 2018).
Bringing krill meal to the (aqua) table
Aside from enhancing fish growth and performance, krill meal supplementation has several proven benefits for aquaculture as it also promotes hepatic health (Torrecillas et al., 2021). The amino acid composition of krill protein is very similar to that of fish meal (Figure 1; Moreno-Arias et al., 2018; Nunes et al., 2011). This generally results in increased feed intake, as reported in different studies documenting a stimulatory effect of different krill products on the appetite of several fish species (Choi et al., 2020).
July/August 2021 AQUA Culture Asia Pacific
Figure 1. Comparative plot for essential amino acid profile (as g/100g diet) of krill meal (inclusion at 11%) and 3% fish meal diets (Moreno-Arias et al., 2018; Nunes et al., 2011)
Made from Antarctic krill, QRILL Aqua (AkerBiomarine, Norway), is known as a feeding stimulant potentiating feed uptake and growth. It also improves fish health and stress tolerance. This product was recently tested in both European seabass and olive flounder, with remarkable results towards improving biological performance, while also enhancing the feed cost-benefit ratios. Fish meal based diets were compared with low fish meal diets supplemented with different amounts of krill meal (5%, 7.5%, and 10% for European seabass; 3%, 6%, 9%, and 12% for olive flounder). After 12 weeks, growth performance results revealed that a krill-supplemented (low fish meal ) feed outperformed high fish meal feed (Figure 2). For European seabass, fish growth improved by 22%, with the final body weight increasing from 54g to 65.6g. Olive flounder’ average final body weight was also higher in fish fed krill meal supplemented diets.
