Abalone Fed Grape Pomace Grow Three Times Faster in California Aquaculture Breakthrough

In Chico, California, a new approach to sustainable aquaculture is taking shape, using the byproducts of the state’s wine industry to feed red abalone. The project is led by the Kashia Band of Pomo Indians of Stewarts Point Rancheria in Sonoma County. Their work focuses on grape pomace, which includes the skins, seeds, and stems left over after winemaking. Traditionally considered waste, this material is now being used as a main ingredient in abalone feed.

The initiative began as a response to a major challenge in abalone farming. Northern California’s kelp forests, the natural food source for abalone, have collapsed in recent years. This left land-based abalone farms searching for alternative feeds that are both affordable and environmentally responsible. With support from California Sea Grant and research collaboration with UC Davis, the team developed dry pellets containing up to 24 percent grape pomace. These pellets are engineered to remain stable in water for several days, accommodating the slow eating habits of abalone.

Feeding trials took place at the UC Davis Bodega Marine Laboratory. The results were notable: abalone fed with the grape pomace-based diet grew three times faster than those given standard commercial feed. Daniel Swezey, oceans and aquaculture director for the Kashia Tribe, confirmed that this growth rate was unprecedented in their experience.

The use of grape pomace addresses two significant issues. First, it provides a sustainable and locally available feed source for aquaculture operations in wine-producing regions such as Sonoma and Mendocino counties. Grape pomace is rich in carbohydrates and nutrients similar to those found in kelp. Second, it offers a productive use for winery waste. California law now requires wineries to divert pomace from landfills to reduce methane emissions caused by decomposition. Repurposing this material as aquaculture feed supports these environmental goals and contributes to a circular economy.

Researchers are now working to improve the formula further. The current version of the feed still contains some fish meal, but the team aims to develop a completely vegetarian pellet that matches the herbivorous diet of wild abalone. This would make the operation even more sustainable.

The Kashia Tribe is moving ahead with plans to build an abalone farm that would be the first Indigenous-run facility of its kind in the United States. They are currently seeking permits and funding for construction. If successful, this model could change how abalone are farmed across the country and demonstrate how agricultural byproducts can be transformed into valuable resources for sustainable food production.