For thousands of years, humans have used aquaculture to raise aquatic animals and plants—and now, research has shown that the practice can help increase the worldwide food supply with low greenhouse gas emissions.
Oral histories date aquaculture to 4000 B.C., according to a lesson from North Carolina State University’s Sea Grant program. The first known written record of aquaculture dates back to the fifth century B.C., with the practice likely originating in China.
The practice has existed in what is today the United States for thousands of years, Peter Kareiva, president and CEO of the Aquarium of Pacific, noted.
“Native Americans had clam gardens, where they terraced the coast, and native Hawaiians had special fish ponds,” he said. “It’s an old technology, but more recently with modernization, it’s the fastest growing food sector in the world.”
Modern fisheries raise various species in large enclosures in bodies of water, Kareiva said. Other operations farm algae and shellfish—mostly clams, mussels and oysters, which require less equipment and work because they remain stationary and do not require feeding by the farmers.
For decades there has been a stigma associated with seafood farming, Kareiva said, including diseased fish escaping and infecting wild fish as well as concerns about efficiency.
“Often they were being fed fishmeal,” Kareiva said. “So you’re catching fish to feed fish, and the amount you had to feed them to get new fish meat was not that efficient.”
Advances in the industry, however, have made aquaculture much more sustainable and efficient, Kareiva said, which is important because in the fight against climate change, it should play a major role due to its resistance to unusual weather phenomena on land and the massive amounts of emissions generated by land-based food production. But a lack of public eduction continues to shroud seafarming in outdated misconceptions.
In a paper called “A 20-year retrospective review of global aquaculture” published in March 2021 by the scientific journal Nature, researchers noted that aquaculture sustainability saw major gains from 1997 to 2017. The same group published a paper in Nature in 2000 that was critical of the practice.
From 1987 to 1997, farmed fish production increased from 10 million metric tons per year to 29 million metric tons, with about 300 species of animals, plants and algae being cultivated worldwide. By 2017, that figure ballooned to 80 million metric tons of fish and shellfish and 32 million metric tons of seaweeds, with over 425 species being cultivated.
During that time, as production nearly tripled from 2000 to 2017, researchers noted that the annual catch of forage fish to make fishmeal and fish oil decreased from 23 million metric tons to 16 million metric tons and the global production of fishmeal from capture fisheries and trimmings decreased from 6.6 million metric tons to 4.8 million metric tons.
“Cattle have been domesticated for 10,000 years, so we’ve had 10,000 years to get better at it,” Kareiva said. “We’re just at the beginning of getting good at growing seafood.”
As seafood and plant farming continues to progress, Kareiva said aquaculture will not only help solve worldwide food production shortages but also the climate crisis. He noted that the raising of cattle and other land animals as food uses far more resources—namely water—and produces an exorbitant amount of greenhouse gases.
It takes 1,847 gallons of water to produce 1 pound of beef, according to Denver Water. This takes into account the water consumed directly by cattle as well as water used to produce the various grass, corn, grains and soybeans they eat. A 1,200-pound cow yields about 723 pounds of beef products, according to the University of Tennessee—which equates to 1,335,381 gallons of water.
When it comes to greenhouse gases, methane—which is 28-times more powerful than carbon on a 100-year timescale, according to the EPA—is of significant concern. A single cow produces between 154-264 pounds of methane gas per year, according to the U.S. Environmental Protection Agency. Mixing in certain types of seaweed into cow feed, however, lowers cow methane production significantly, the agency notes: red seaweed could lower methane emissions by as much as 98% in cattle with only a 0.2% addition to animal feed per day. Other types of seaweed have been shown to lower cattle methane emissions by 67% with only a 1% seaweed mix.
Studies have shown that aquaculture, however, has a much smaller carbon footprint.
In the face of climate change, Kareiva noted that aquaculture is also immune to unprecedented weather phenomena and drought that threaten land-based food production. And aquaculture, he added, could have a more positive environmental fallout than the rise in electric cars across the state because large amounts of electricity are generated using fossil fuels. According to the U.S. Energy Information Administration, fossil fuels are used to produce 60% of the nation’s electricity.
“I don’t see us being able to address climate change unless we address our food systems,” Kareiva said. “And I don’t see us addressing our food systems that effectively unless we expand aquaculture.”
In addition to its climate resilience, using less resources and producing fewer emissions, Kareiva said the cultivation of shellfish would actually clean water, as many of those species are filter feeders, which remove excess nitrogen and other pollutants from water.
Challenges to local cultivation
While it’s clear that aquaculture offers significant benefits over land-based agriculture, there are still challenges to fostering the industry’s growth locally.
The U.S. imports 70-85% of its seafood, according to the National Oceanic and Atmospheric Administration, which estimates half those imports are produced via foreign aquaculture. The national seafood trade deficit grew to $17 billion in 2020, the report states.
“We have great seafood right off our coasts,” Kareiva said. “It just doesn’t make any sense to be importing seafood from countries that don’t regulate environmental destruction anywhere near as well as we do, or that even violate fishing rules.”
While local aquaculture should provide local restaurants and stores with fresh seafood, according to Kareiva, he noted that it needs to be done sustainably. This includes reducing impact on natural ocean environments as well as those on local communities.
In Long Beach and Los Angeles, for example, port operations would make hosting aquaculture facilities far more difficult than other areas. According to a 2021 NOAA analysis of natural and cultural resources as well as various industry, leisure and trade routes along the Southern California coast, areas near Santa Barbara and Ventura are the most viable, followed by waters between Malibu and Santa Monica.
From LA-Long Beach to Newport Beach, there is practically no water area that would be able to accommodate aquaculture due to the high volume of container ships, tankers, commercial fishing and cruise ship travel. Areas near San Clemente and San Diego also have no viable locations due to military operations as well as passenger and other vessels.
While the federal government has identified locations for aquaculture around the country, Kareiva said that regional and local governments have become a roadblock to allowing such facilities nearby.
“They’re always wary of being criticized for allowing something,” Kareiva said. “So at one level, the federal government is supportive of aquaculture, but that doesn’t mean that it reaches down to the level of permitting.”
Lack of public awareness
Part of that fear is likely a direct result of the public’s lack of knowledge. Outdated narratives on the topic of aquaculture have hindered social acceptance of the industry in the U.S., according to a new report co-authored by Kareiva. The study, titled “Are all benefits equal? An exploratory analysis of coastal perspectives of seafood farming expansion in the United States,” found that of the people surveyed in Western and Northeastern coastal states, 49% and 61% had “never heard” or “knew little about” marine aquaculture and seaweed farming, respectively.
“Anytime somebody proposes an aquaculture operation off the coast, it’s common to see protests against it,” Kareiva said. “You shouldn’t have a knee-jerk reaction.”
Throughout the course of the study, respondents were educated on aquaculture using a series of videos produced by the Aquarium of the Pacific: “Ocean to Table: Stories of Food, Farming, and Conservation.” The series highlights responsible marine aquaculture and ocean farming in the U.S., bringing together seafood farmers, scientists and chefs who share their stories.
Over half of respondents who began with a negative opinion of seafood farming were in favor of the industry after watching one of the videos, the report states. Respondents ranked scientists, seafood farmers and aquariums/museums as the best sources for education on the topic.
The study was authored by Brianna Shaughnessy, Amalia Almada, Kimberly Thompson and Michelle Marvier from the School for the Environment at the University of Massachusetts Boston, the University of Southern California Sea Grant Program, and the Department of Environmental Studies and Sciences at Santa Clara University. It was published in The Journal of the World Aquaculture Society.
If the U.S. wants to truly take a holistic approach to fighting climate change, including aquaculture, Kareiva said education is the first step. Once the public becomes aware of the modernized sector and, in turn, more supportive of it, local governments would be more likely to approve them.
“This climate thing is serious,” Kareiva said, noting he’s been involved in climate science for 30 years. “It’s not the end of the world or an existential risk, but it really can wreak havoc on lives and communities. Aquaculture and doing a better job raising food from the ocean has to be a big part of the climate solution.”