Amid Arizona’s arid landscape, a unique experiment in sustainable fish farming unfolds. Mainstream Aquaculture, an Australia-based company, is cultivating barramundi, a tropical fish species, in the desert, aiming to provide American restaurants with a sustainable seafood option.
The journey begins with Dan Mohring, who navigates his truck down a dusty road, towing a trailer filled with a nutritious blend of beef, chicken, fish, and other ingredients. This mixture is launched into the ponds, creating a feeding frenzy among the barramundi. In a few months, these fish will become a meal themselves.
Mainstream Aquaculture positions itself as an eco-friendly alternative to ocean-caught seafood. The company highlights the benefit of reduced travel distances for food, which cuts down on pollution from global shipping. Moreover, the nutrient-rich water from the ponds is reused to irrigate crops like Bermuda grass, which is sold for livestock feed.
“We’re in the business of water,” said Matt Mangan, who leads Mainstream’s U.S. operations. “We want to be here in 20 years’, 30 years’ time.”
However, the sustainability of large-scale fish farming in such a dry region raises concerns for some experts. The critical issue revolves around water use, particularly whether aquaculture is a reasonable use of groundwater, a finite resource in Arizona.
The farm relies on groundwater, which is nonrenewable. Unlike Colorado River water, groundwater’s use is less regulated, leading to debates about its proper management. Sarah Porter, director of Arizona State University’s Kyl Center for Water Policy, noted, “As long as groundwater is treated as an open resource in these rural parts of Arizona, they’re susceptible to new industries coming in and using the groundwater for that industry.”
Some scientists advocate for aquaculture as a means to alleviate pressure on wild ocean ecosystems affected by overfishing. It could also mitigate supply chain disruptions caused by tariffs on seafood imports, as reported by the USDA.
A Two-for-One Approach?
(Photo by Sarah Ventre – KJZZ)
At the University of Arizona, professor Kevin Fitzsimmons’ lab showcases an aquaculture system where tilapia swim in tanks that filter into mussel tubs and vegetable patches. Fitzsimmons mentored the student behind the tilapia farm now acquired by Mainstream for barramundi cultivation.
“I don’t think desert agriculture is going away,” Fitzsimmons remarked. “Obviously, we want to do it as water-efficient as possible.”
Others remain skeptical. Jay Famiglietti, from ASU, dismisses the idea of desert fish farms, citing evaporation concerns. However, Mangan counters that heat loss during winter is a more pressing issue, leading to innovations that cut water use by half.
The farm’s wastewater, described as “essentially liquid fertilizer,” supports crops like Bermuda grass. Yet, Famiglietti criticizes this for sustaining cattle farming, a significant greenhouse gas contributor. “Doing two suboptimal things doesn’t make it better,” he said.
Groundwater: A Finite Resource
The farm’s operations depend heavily on groundwater, a vital yet limited resource. In Arizona, groundwater use is subject to varying levels of regulation. Some areas, including Dateland, have looser rules, with landowners allowed to pump “reasonable” amounts, as per ASU water law expert Rhett Larson.
Mainstream’s water use parallels that of a large ranch or even some Phoenix suburbs, according to calculations by Sarah Porter. Despite using the water twice, the aquifer remains depleted.
In its quest for growth, Mainstream also aims to collaborate with local farmers to utilize nutrient-rich wastewater for hay production. Some local farmers have shown interest in this approach.
Rethinking Seafood Supply
Pallab Sarker, an expert from the University of California, Santa Cruz, emphasizes reducing dependency on small wild fish for feeding farmed species. “We should not rely on ocean fish to grow fish for aquaculture to meet the demand for humans,” Sarker stated.
Mainstream sources its fish feed from Skretting and Star Milling, but the origins of the base ingredients remain uncertain. Fitzsimmons noted that pollution and overfishing already challenge the fishing industry. He argues that aquaculture offers a viable alternative to policies like those of Trump’s, which aim to open marine areas for fishing.
“We can’t keep hunting and gathering from the ocean,” Fitzsimmons concluded.
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