With the global population just surpassing 8 billion people, there has never been a greater demand for seafood. There is great potential for marine finfish raised in aquaculture systems to help meet that demand. However, domestic production of marine finfish and long-term success of the industry is limited by the industry’s ability to produce sufficient quantities of high-quality larvae and juveniles. Existing commercial microdiets fail to supplant inconsistent and expensive cultured live feeds in marine finfish hatcheries. Currently available microdiets are subject to high rates of nutrient leaching when in suspended in water and rapid sinking rates which result in poor feeding efficiencies and may not meet the nutritional requirements for marine fish larvae. Ultimately, these factors manifest in poor larval growth, low survival outcomes, and elevated malformation rates in larvae. Recent studies have found liposomes to be a novel and successful method of delivery of water-soluble compounds to marine finfish larvae via enriched live feeds. Building upon this research, we have incorporated liposomes into larger alginate-based particles, resulting in liposome-containing complex particles (LCP). We hypothesize that these liposome-containing complex particles will show low rates of nutrient leaching when compared to existing commercial-type microdiets while delivering ‘complete nutrition’ to the larvae. Early iterations of these liposome-containing complex particles containing hydrolyzed casein have been tested in growth trials using Inland silverside (Menida beryllina) larvae as a model organism. These early trials show promising results when compared to both liquid- and commercial-type microdiets, as revealed in similar growth parameters between fish fed our LCP diet and those fed a commercial standard.
Despite this progress, further research and development is needed in order to optimize these liposome-containing complex particles to be competitive with existing larval weaning diets. Our next steps in this research project are to: 1) optimize buoyancy of complex particles to increase incidence of larval capture when in suspension, 2) evaluate the leaching of critical nutrients when complex particles are suspended in sea water, and 3) evaluate the success of these diets for commercial species, such as Seriola sp., a valuable commercial finfish species. If successful, this research may transform the way marine finfish larvae are fed in commercial hatcheries and enhance larval growth, survival, and overall output in production systems. Moreover, this diet has the potential to reduce the need for live feeds, a sought-after goal of the industry that would spare hatcheries labor and resources. Lastly, this liposome-based complex particles could have broader impacts beyond the scope of larval nutrition and act as a delivery method for vaccines, antibiotics, and other bioactive compounds.