By: Natalie Overton

This article is, in my opinion, best introduced by a few words from the crustaceous American sweetheart, Sebastian the crab. “Under the sea~under the sea~Darling it’s better down where it’s wetter!”— these lyrics run true now more than ever.

Achieving food security is exciting. It challenges us, as humans, to do what we’re best known for: adapting. We’ve all seen the changes that have reshaped our climate. Usable agricultural land is running out. Faced with a growing world population, we are challenged to feed everyone and to do so in a sustainable way. Dr. Hunter Lenihan and many of his fellow researchers turn to aquaculture as a new frontier, teeming with opportunities for innovation and sustainable solutions.

A researcher and professor of marine and fisheries ecology at UCSB’s Bren School of Environmental Science & Management, Dr. Lenihan’s research spans oceans from Norway to Santa Barbara. “This is the blue revolution,” He tells me at the start of our interview, referencing the green revolution of years past. Indeed, aquaculture production has doubled from 60 to 120 million tons in the 30 years between 1970 and 2000, and has shot up to over 140 million tons in the last decade.At this rate, aquacultural production is quickly outphasing that of traditional fisheries. This is great news for species like dolphins and octopi—common bycatch of capture fisheries. Aquaculture doesn’t take from wild populations, so it doesn’t disrupt food webs, damage habitats, or kill animals we don’t mean to kill. When doing aquaculture right, we cut some of these negative impacts out of the equation. As we move into this new phase, this blue revolution, we must tailor the production to fit our goals: food security, sustainability, and environmental consciousness. Dr. Lenihan poses the question that sets the tone for the rest of the meeting:  “How do we learn from the green revolution to make a blue revolution that’s more sustainable?”

He hopes to hit the sweet spot of widespread sustainable protein production by addressing disease prevention, increasing the protein feed to product ratio, and by transitioning to vegetarian feed sources. Disease, at least in my mind, is the first red flag that pops up when I imagine a future that relies heavily on aquaculture. We know that diseases spread rapidly when we raise large amounts of animals together very quickly—that’s a lesson we’ve learned from agriculture. In poorly executed cases of large scale aquaculture, the dense fish populations become breeding grounds for parasites and infections, which can infect wild fish populations nearby. Aside from taking a toll on the natural fish populations, diseases indirectly harm the natural environment because they prompt a more liberal usage of pesticides and antibiotics. One group that Dr. Lenihan studied in Norway, for example, sprayed entire bays with a pesticide to eliminate parasites. There are other, more sustainable ways to address disease, though. Some propose simply breeding animals that are less susceptible to disease, and others try to do aquaculture with smaller densities of fish, or in less fragile environments.

Once we’ve cleared the hurdle of infectious diseases, Dr. Lenihan and I shift our discussion to protein efficiency. The key component here is fine-tuning the protein feed-to-product ratio. This allows researchers to engineer the most efficient kinds of feed, and to breed the most efficient animals. As of today, aquaculturists have gotten this ratio down to 1:1—for every gram of protein the fish consumes, its meat offers a gram of protein. That’s 100% conversion efficiency—stellar, compared to land-based animal protein sources. Eggs topping the chart at 31% conversion efficiency for land-based protein sources, while on the lower end of the spectrum, beef has a measly conversion efficiency of 3%.

Hunter and his group are trying to make this process even more efficient by using vegetarian feed. This relies on the basic principle that growing vegetables is a lot more energy efficient than growing animals. The group Dr. Lenihan is working with, headed by Dr. MargarethØverland, is feeding fish yeast from wood chips and algae and thanotropic bacteria. Dr. Ø verland’s group, based out of the Norwegian University of Life Sciences, aims to develop even more efficient feeds. This university was also responsible for hybridizing the Atlantic Salmon, the same one we see at many grocery stores today.  

Another aspect of his work is to determine whether the proteins that Øverland’s group is proposing have a lower environmental footprint than the best traditional feeds available on the market today. They do and that’s surprising, because over the past twenty years, salmon feed composition has sprung from 10% to 70% plant based—so you’d think how could we get better than plants?! Part of the reason for this shrunken environmental footprint of feeds is the transition from using human foods like soybeans to instead using microbial sources like yeast, which are far more productive. 10,000 times more productive, in fact.  

Mollusks have an even lower carbon footprint, so for folks who like to do the most, this is the way to go. According to Dr. Lenihan, the best way to move forward is with filter feeders, like mussels or abalone. Abalone populations have had it rough recently, with their numbers sharply declining around the world. Most abalone industries, except those in California, have collapsed.These slow growing mollusks have been intensely overfished, and they’ve suffered from withering syndrome, a disease that spreads when the water warms. The focus of Lenihan’s research is to understand what populations of abalone were impacted, where, and to uncover the environmental triggers for withering disease. One way to combat this while raising farmed abalone is to select animals that are resistant to disease when creating a hatchery program. It looks like the main trigger for withering disease is stress. The abalone that live in the tidal zone are exposed to air every day, and this stresses them out and makes them more susceptible to disease.

The most important finding so far, says Dr. Lenihan, is that we can mix disease epidemiology and ecology—realizing that the best way to maintain a healthy farmed abalone population is to remove most of the diseased organisms (which are still safe for human consumption) to prevent contagion and keep the population strong and healthy. This approach is counterintuitive, which makes it all the more important. Leaving a population alone is worse than continuing harvest or doing planned harvest. “And that’s the value of science,” Lenihan says, “Because science doesn’t just take the knee-jerk reaction of what you think is right.”

Another big challenge facing aquaculture today is that existing management programs, for the most part, take a one-size-fits-all regulatory approach. And recently, the tide of opinion has turned against this method. “There’s been a big shift in the environmental NGO world,” Dr. Lenihan tells me, “from ‘we need to be making reserves,’ to “we can’t be making reserves everywhere, so how do we manage the population of fish and other organisms in a sustainable way?’ And the way we’re doing that is through collaborative, community-based fisheries.”

His perspective, needless to say, is not universal. Focusing on short-term gains while largely disregarding long-term consequences is the modus operandi for folks around the world.  In Chile, for example, overcrowded (though temporarily profitable) fjord-fisheries were inevitably hit with disease and completely wiped out. Meanwhile, Chinese grouper fisheries are trying to set up big cages of their fish in Polynesian lagoons, all destined to be shipped back to China. This is largely unsustainable, focused solely on the short-term economic benefits of the program. These businesspeople aren’t acknowledging the inevitable consequences of overcrowding, like disease and population decimation. Any fish scientist, it’s safe to say, would not recommend this course of action. They’re doing it anyway. It’s profitable, for now. This mindset, which Hunter terms “anti-science”, dominates our government too. Many of our own businesses treat science-based regulations as just another way to reduce their bottom line. The idea, from their perspective, is that they’ll make less money if regulators curtail human activity in the environment. But Hunter insists this isn’t true. Hunter adds that while short-term growth may always look good from the business perspective, “It’s not a given that it’s a good thing all the time.” Short term growth can indicate fragility—often, it’s just too good to be true.  

His cumulative research experience calls for widespread yet individualized, ‘habitat-based’, fisheries management. This big-picture approach assesses all aspects of the habitats they’re working with: changes in temperature, common diseases, neighboring species, natural predators, environmental stressors, etc. This is opposed to the traditional management style, which only looks at one species by itself. NOAA provides a good example of what they call ‘ecosystem-based’ management. “if a particular species’ population is declining, fishery managers might reduce the annual catch limit the following year in an attempt to reduce overexploitation,” the article begins, tracing the traditional approach. “However, fishing is only one variable affecting a species’ population. Additional elements come into play, such as interactions with other species, the effects of environmental changes, or pollution and other stresses on habitat and water quality.”

That’s why scientists and management and other community members have to unite to solve these problems. That’s the whole directive behind community-based management, which incorporates citizen feedback into the decision-making process. For example, a group of rock crab fishermen in Santa Barbara contacted the Bren School of Environmental Science & management for help after noticing that the population seemed in worse shape than regulators had predicted. “They [the fisherman] learned how to collect information that would feed back into management models that would help them control how much they should fish, where and when they should fish.” Dr. Lenihan told me, “so that’s what collaborative management is, it’s integrating the fishermen that are out on the ocean, seeing things every day and getting data, and using that to manage themselves.” The people actually out there on the water are a valuable source of information. When these three groups don’t cooperate effectively, we end up with tragically inefficient management systems.

And it’s not a matter of technology, Hunter promises. “We can figure out the solutions. We have the technology. It’s a matter of will. It’s a matter of designing management programs that actually work.”  This goal—getting scientists, management, and fishermen to work together smoothly, is as much a priority for Bren as it is for Dr. Lenihan himself. As he tells me, sounding slightly relieved, he’s in the right place. “Frankly, that’s what the Bren school’s all about.”