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Open ocean – the next agricultural frontier

Updated: Sep 22, 2021

By: Rachel Rhodes, MESM '21

Scientists provide site planning and guidance for managers and investors as the demand for offshore aquaculture continues to rise

The sun is barely peeking over the horizon and already workers are busy amongst the rows of strawberries in the Southern California coastal town of Oxnard. While a common sight on land, this same buzz of activity may soon be happening four or five miles out at sea. But unlike the agriculture fields we are used to, these marine farms are a bit more challenging to maintain. Farm workers would need boats to access giant cages out on the open ocean where swift moving currents, waves, and the unrelenting glare from the sun are all part of the job.

So why are farmers looking to the shoreline? This new type of farm could be a promising solution to increasing demands on agriculture. Food production will need to expand by 50 percent to meet the growing needs of a global population expected to exceed 9 billion people by 2050 [i]. So despite the challenges, offshore aquaculture could serve as a lower energy, land, and freshwater intensive strategy to ensure future protein-rich food security.

In California, the expansive, nutrient-rich coastline provides many potential offshore aquaculture sites. However, farmers need to somehow navigate the unclear regulatory process, technological challenges of operating offshore, competing stakeholder interest, and environmental concerns regarding potential impacts on ecosystem health.

At the University of California, Santa Barbara (UCSB), there is ongoing research to find solutions that could help alleviate some of these challenges and expedite the planning process. I spoke to Rebecca Gentry, a Bren School of Environmental Science & Management alumnus who is currently researching offshore aquaculture as a postdoctoral researcher at Florida State University. Gentry said she knew at the onset of her research that marine aquaculture could be vital to a future sustainable global food system. However, she also knew aquaculture comes with some risks, especially when operations are poorly planned or operated. She set out to understand how to best manage this growing industry in a way that would benefit both humans and the environment.

To understand the potential impacts of offshore aquaculture, Gentry teamed up with Steve Gaines, the Dean of the Bren School, Sarah Lester, an assistant professor at Florida State University, and other researchers from UCSB and California Polytechnic State University. They wanted to first understand the potential impacts and interactions of offshore aquaculture, so reviewed dozens of reports and documents on the impact of aquaculture. They found that farms have varying impacts depending on the species farmed, physical characteristics of the site, and farming practices. If not carefully planned, they found that surrounding wild populations could suffer from chemical pollution from pesticides and fertilizers, transmission of diseases, gear entanglement, spread of invasive species, and interbreeding between escaped and wild fish [ii].

Despite these potential risks, good planning and site selection can help minimize the impacts of offshore aquaculture. The research team created a recommended spatial analysis approach to site aquaculture locations offshore. This guide includes a key set of questions, analyses stages, and helpful resources. As part of a broader marine planning process, the type of spatial analysis described by Gentry and the team could help find the best location, number, and density of sites to minimize potential environmental harm.

Another primary challenge in marine spatial planning and aquaculture development is how to balance the interests of different ocean users to minimize costs and conflicts. These different stakeholders include coastal residents, environmental regulators, recreational ocean users, and commercial operators such as shipping companies and fisherman. Some of these stakeholders are directly competing to use the same physical sites. Others are concerned that poorly managed farms will impact the health of ecosystems beyond the footprint of the farm.

To help reduce potential conflicts, Lester and Gentry then worked alongside UCSB researchers, including Carrie Kappel, Steve Gaines, and Chris Costello, and others to create a marine spatial planning tool that assesses potential conflict from different ocean users. To analyze the tradeoffs between environmental impacts and different stakeholders’ interests the team of scientists modeled over 1000 potential sites for mussel, finfish, and sugar kelp farms in Southern California. Based on this analysis, they determined the spatial plans that generate the highest revenue while simultaneously minimizing environmental impacts and conflicts among stakeholders. This type of modeling can help simplify complex decision-making processes when considering site locations [iii].

Offshore aquaculture has groundbreaking potential among sustainable food security practices. However, the regulatory uncertainties and inherent challenges of marine spatial planning impedes the development of aquaculture farms. But thanks to the efforts of researchers at UCSB, Florida State University, and California Polytechnic State University, the planning process for offshore aquaculture farms has a greater chance of success and fewer ecological impacts, allowing local farmers to take advantage of our abundant and productive shoreline.



[i] FAO. 2017. “The future of food and agriculture – Trends and challenges.” Rome. In:

[ii] Gentry, Rebecca, et al. “Offshore aquaculture: Spatial planning principles for sustainable

development.” In: Wiley Ecology and Evolution, 7: 733–743. doi: 10.1002/ece3.2637.

[iii] Lester, S.E., et al. “Marine spatial planning makes room for offshore aquaculture in crowded coastal waters.” In: Nat Communication 9, 945 (2018) doi:10.1038/s41467-018-03249-1.

Image Source: The Current, UCSB. In:


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