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Striving for Sustainability in the Aquaculture Industry

Striving for Sustainability in the Aquaculture Industry

Newly developed fish-free feed offers more sustainable solution for aquaculture industry

Lauren Everett
Pallab Sarker.

Pallab Sarker, associate research professor in the department of environmental studies at the University of California, Santa Cruz (UCSC), discusses the importance of shifting the industry of aquaculture toward more sustainable practices. One way to accomplish this is through the development of feed that uses marine microalgae to eliminate the need for wild-caught foraged fish for feed ingredients.


Q: Can you discuss your ongoing research in the field of aquaculture?

A: I am deeply passionate about my current research at UCSC to solve the enormous sustainability challenges that the aquaculture industry is confronting today. My research involves shifting aquaculture to sustainability by redesigning the aquaculture feed composition. To accomplish this goal, my team recently received two grants to execute this type of experiment, which is an exciting opportunity. Our current focus is to develop a more ocean-friendly feed formula for farm-raised rainbow trout, which accounts for most of the fishmeal and fish oil used in aquaculture fish feed. The grant will allow my team to develop fish-free feed—eliminating fishmeal and fish oil from the aquaculture diet—for rainbow trout by combining marine microalgae.

We recently published a major breakthrough, the first proof of concept to develop fish-free feed for farmed tilapia combining marine microalgae. We demonstrated high performing sustainable tilapia with fish growth, economic viability, and nutritional value for human consumers. So, now we can redesign the diet for trout. We need several stepwise experiments to make very good conclusions about whether we can achieve the goal to develop fish-free feed for rainbow trout.

Q: What are the main limitations of current fish feeds? Why is a fish-free alternative needed?

A: Aquaculture is the fastest-growing food production sector globally, and now it produces over half of all fish for human consumption. This is a very young industry, but growing rapidly. To meet the demand for fish, there needs to be sustainable expansion of this industry. This requires reducing the use of ocean-derived, wild-caught fishmeal and fish oil from foraged fish—small to intermediate fish like anchovies, mackerel, sardines, herring—that are currently being used for fishmeal and fish oil in aquaculture feed. These fish are very important as ocean food sources. It is very unfortunate that today, about 19 million tons of wild fish—20 percent of the total global catch—are destined for fishmeal and fish oil every year, even though 90 percent of these harvested fish are good for human consumption. Analysts project that the current rate of fishmeal and fish oil consumption that aquaculture demands could outstrip the supply of foraged fish by 2037. This will have disastrous consequences for food security of millions of humans around the world, and for sea birds, mammals, etc. that forage on these fish. It is important that we replace the wild-caught fishmeal and fish oil-produced aquaculture feed. It’s unfortunate this has become the status-quo. We must do better, and we have an obligation to do better for our planet.

Q: What impact could the introduction and wide use of microalgae feed have across the aquaculture industry?

A: It would have a huge impact because microalgae is an excellent source of proteins, minerals, and vitamins. Microalgae can cultivate in nonarable land and produce many times more biomass per unit area than terrestrial crop plants. Microalgae are excellent sources of protein, lipid, essential amino acids, minerals, vitamins, and omega-3 fatty acids (EPA and DHA) that meet the nutritional requirements of fish. Microalgae are able to convert phosphorus and nitrogen nutrients (organic wastes) into a valuable biomass and will not compete for human and other animal food. Microalgae show promise as possible replacements for fishmeal, fish oil, and plant protein in feeds for tilapia and other finfish and crustaceans. Several leading aquafeed companies recently have already realized the potential and have started microalgae production for aquaculture feeds.

Q: Can you explain the process of making the microalgae feed?

A: First, we examine the biochemical composition of microalgae and then determine how well fish could digest specific varieties of microalgae. Then, we formulate the diet based on digestible nutrient content. Finally, we conduct separate series of experiments to see how well fish grew using these individual ingredients as replacements for either fishmeal or fish oil, or combining these microalgae.

Q: What can aquaculture professionals learn from traditional agriculture?

A: Industrial agriculture is facing tremendous environmental challenges now, from pollution, to loss of arable land, emissions, etc. Now, the aquaculture industry is young. If we don’t do our job carefully, cautiously, thoughtfully, then unsustainable aquaculture practices only exacerbate these challenges. We need to be careful of the current practices of aquaculture and aquaculture feed and need to simultaneously conduct environmentally sound and socially acceptable practices.

Q: What other aspects of aquaculture are being studied to make the industry more efficient and sustainable?

A: I am highly interested in developing integrated aquaculture and agriculture, which is one of the guiding principles of sustainable aquaculture. Now my team is working to develop ecological aquaculture principles and practices at the Center for Agroecology & Sustainable Food Systems at UCSC. For example, we conduct research on the integration of recirculating aquaculture systems with fish-effluent-raised vegetables (aquaponics and soil-based) and will quantify the effects of such integration on nutrient cycling, plant growth, disease suppression, financial performance, and life cycle environmental impacts. Our results will stimulate and inform research on circular economy concepts to recycle the aquaculture effluent for organic vegetable production. This sustainable integrated aquaculture and agriculture system will enhance the local food (fish and vegetables) production.

Q: What emerging or future trends do you envision for the aquaculture sector?

A: Future innovations I am looking forward to seeing include more technological advancement in aquaculture, like using artificial intelligence, for aspects like developing feeding management systems. We must continue to move away from unsustainable aquaculture, and create more sustainable feed.


Pallab Sarker, associate research professor in the department of environmental studies at UCSC, is a sustainable aquaculture scientist. His research interests involve shifting aquaculture, the world’s fastest growing food sector, to sustainability by redesigning the composition of aqua-feeds because they drive life-cycle environmental effects of aquaculture, both inputs and emissions (pollution). Shifting aquafeeds to more sustainable ingredients is a key part of sustainable aquaculture. He is interested in developing ecological aquaculture principles and practices. The main focus of his current research is to develop a fish-free and crop-free aquaculture diet by combining different species of micro- and macro-algae and developing targeted biochemical manipulations to maximize the diet’s nutrient quality, economic viability, and benefits for environmental conservation.