Blog

In a promising demonstration of integrated food production, scientists from the University of California, Santa Cruz, are collaborating with Pie Ranch – a nonprofit regenerative farm in Pescadero, California- to explore the potential of aquaculture wastewater as a sustainable irrigation source for native plants.

Since October, the research team has been repurposing nutrient-rich “backwash” from recirculating tanks housing 200 rainbow trout to water select native species grown onsite. The study aims to evaluate whether this aquaculture effluent can enhance plant growth while reducing water waste and improving soil health- an approach that could provide meaningful synergies between fish and crop farming.

Anne Kapuscinski, director of UC Santa Cruz’s Coastal Science and Policy Program and a long-time leader in sustainable aquaculture research, is spearheading the project. “Rather than keeping aquaculture and agriculture separate, we’re exploring how their integration can boost climate resilience, conserve resources, and improve land stewardship,” said Kapuscinski.

The experiment, funded by the UC Santa Cruz Center for Coastal Climate Resilience and Kapuscinski’s endowed chair in Integral Ecology and Environmental Justice, involves growing three species of native plants- half irrigated with aquaculture backwash, half with well water- and monitoring differences in biomass, leaf area, soil nutrients, and water use efficiency. Preliminary results are expected in spring 2026.

Beyond the greenhouse, the project also supports ecosystem restoration. The Amah Mutsun Land Trust, in partnership with Pie Ranch, is using some of the plants in post-wildfire recovery work on land burned during the 2020 CZU Lightning Complex Fire. The trust approved the species selection, prioritizing native plants with ecological and cultural significance- though details on medicinal use remain protected to honor Indigenous protocols and prevent misuse.

“This is part of restoring our role as stewards of the land,” said Amah Mutsun Tribal Band Chairman Valentin Lopez. “We are combining traditional knowledge and science to heal our landscapes.”

The practical design of the trial required close coordination between aquaculture and agriculture timelines. “We were constantly trying to sync the growth cycles of fish and plants,” said Leonard Diggs, director of Pie Ranch’s Cascade Regenerator Program, which supports BIPOC farmers and serves as the agricultural lead for the study.

The collaboration continues a longstanding relationship between UC Santa Cruz and Pie Ranch, co-founded by alumni Nancy Vail and Jered Lawson. “For us, this is about bridging academia and real-world challenges,” Lawson said.

Experts in the field see this kind of integrated model as both a return to roots and a blueprint for the future. “Family farms historically reused everything- including nutrient-rich effluent,” noted aquaculture specialist Kevin Fitzsimmons, who was not involved in the study. “It’s encouraging to see a return to holistic, closed-loop systems.”

Kapuscinski hopes the research will offer a scalable model for farms looking to diversify their operations, reduce waste, and contribute to both food production and ecosystem restoration. “We’re not just testing if fish water helps plants grow- we’re asking how we can reimagine the relationship between land and water in agriculture.”