Treating and Transforming Squid Processing Wastewater at Ventura Harbor

This project explores a circular, nature-based solution for treating and transforming squid processing wastewater (“stickwater”) produced by California’s market squid fishery, with a focus on the Port of Ventura. Stickwater is a nitrogen-rich byproduct – full of ink and other bodily fluids – that currently needs to be disposed of three nautical miles offshore. This costs fishermen time and fuel, and mishandling can result in fines. As Ventura squid landings are expected to grow with the planned transfer of the Port Hueneme squid fleet, identifying alternative treatment strategies is increasingly important.

We evaluate the feasibility of using macroalgae Ulva spp. (sea lettuce) to remediate stickwater while producing a value-added biomass. To test this concept, we conducted a minimum viable product (MVP) pilot-scale experiment. Results showed that Ulva can survive and grow in stickwater-amended seawater, with optimal performance at moderate concentrations. While nutrient dynamics – particularly ammonia behavior – revealed complexities that need to be tested further, the experiment supports the potential for macroalgae to phytoremediate stickwater while producing a nitrogen-enriched algal biomass at an enhanced growth rate.

We also assessed downstream applications for the resulting biomass and identified seaweed-based biofertilizer as the most viable near-term product. This creates a dual-value system: treating wastewater while generating something valuable. The proposed Squid Inc. approach reimagines stickwater as a recoverable resource rather than waste, turning an environmental problem into an economic opportunity that creates new value streams for coastal industries.

Acknowledgements

UC Santa Barbara Bren School: Emily Cotter, Environmental Innovation Program Manager and Lecturer (Primary Advisor); Dr. Christopher Free, Research Professor (Primary Advisor); Dr. Steve Gaines, Distinguished Professor Emeritus (External Advisor); Dr. Patricia Holden; Dr. Arturo Keller; Dr. Chris Jerde; Trace Martin; Sage Davis

Monterey Bay Aquarium: Tyler Isaac, Aquaculture Program Manager, Seafood Watch (External Advisor)

Lab Testing & Experimentation: Ken Marchus (MSI Analytical Lab); Elisa Halewood (Carlson Lab); Christoph Pierre (The REEF); Matthew Elliott (Hubbs Seaworld Research Institute)

And all of the fishermen, offloaders, Port of Ventura officials, and other stakeholders that helped along the way.