Microencapsulated algal feeds as a sustainable replacement diet for broodstock in commercial bivalve aquaculture

Abstract

The global bivalve shellfish industry makes up 25% of aquaculture, is worth USD $17.2 billion year −1 , and relies upon a supply of juvenile bivalves produced by adult broodstock in hatcheries. Today large quantities of live algae are grown to feed broodstock at $220 kg −1 , driving highly unsustainable energy and resource use. New advances in algal and microencapsulation technology provide solutions. We developed microencapsulated Schizochytrium algae diets, which can be produced sustainably at < $2 kg −1 from organic side-streams, and are shelf-stable to minimise waste. Physiological, histological, and cutting-edge metabolomic analyses demonstrate that in commercial settings sustainable microencapsulated diets facilitate improved sexual development and 12 × greater omega-3 levels in oysters relative to conventional live algal diets. Every tonne bivalve protein produced instead of fish spares 9 ha, 67 tonnes CO 2 , and 40,000 L freshwater. Further research into microencapsulated diets could support bivalve industry expansion, and contribute towards a step-change in sustainable global food production through improved aquaculture practices.

Investigation of the potential of liposome and microparticulate feeds to partially replace microalgae in the nursery rearing of green‐lipped mussels ( Perna canaliculus )

“…Consequently, considerable research is currently underway to develop artificial feeds that could reduce dependence on live microalgae for feeding juvenile shellfish (Carboni et al, 2016;Libini et al, 2017;Mazón-Suástegui et al, 2017;Willer et al, 2020).…”

Wild fish consumption can balance nutrient retention in farmed fish

“…Seafood processing of mackerel redirected to human markets would theoretically still retain 47,321 t of by-products (that is, the inedible portion), which could partially replace marine ingredient supply. Across all species, allocating 100% of ECM fish currently used as feed for human consumption would require an additional 69% of fish oil, either from new sources 28 – 30 or from more effective by-product usage. Redirecting feed fish for human food could produce 600,000 t of by-products for use as marine ingredients.…”

“…oil can be an effective source of omega-3 for salmonids 28 and can be grown heterotrophically using sugar cane or beet by-products. There are trade-offs in environmental performance and cost compared with marine ingredients through high-energy consumption, but performance continues to improve and production is scalable 30 , 64 . Other ‘novel’ alternatives to fish oil, such as yeast oil or genetically modified omega-3 plant oils 28 , are also entering the market.…”

Isotopic techniques in aquaculture nutrition: State of the art and future perspectives

“…67 In addition it has been demonstrated that the use of inert feeds promotes lower CO 2 emissions, reduced energy and antibiotic use as compared with the production of live feeds. 68 The chronological, gradual replacement of live feeds by inert feeds has required multidisciplinary research, and the application of traditional and advanced nutritional methodologies has been of further assistance. Additional knowledge on nutritional physiology aspects has been acquired through the use of isotopic techniques, and this has in turn contributed to improve the feeding schemes for larval and juvenile stages of different edible and ornamental aquaculture species.…”