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Reviving an Ancient Bond: Grape Pomace Yields Remarkable Results in Abalone Aquaculture

A major hurdle in sustainable aquaculture – sourcing cost-effective and environmentally friendly feed – may have a surprising solution: the leftovers from California’s wine industry. A groundbreaking project, spearheaded by the Kashia Band of Pomo Indians of Stewarts Point Rancheria in Sonoma County, is demonstrating that grape pomace – the skins, seeds, and stems discarded after winemaking – can serve as a highly effective primary ingredient for red abalone feed.

The initiative successfully addressed the challenge of feeding abalone in land-based systems following the collapse of Northern California’s kelp forests, the snails’ natural food source.

Three Times the Growth

The initial feeding trials, conducted with practical support from California Sea Grant and research collaboration with UC Davis, showed exceptional results. Researchers formulated specialized dry pellets incorporating up to 24% grape pomace. The pellets were meticulously designed to maintain stability in water for days, a crucial requirement given the abalone’s slow, deliberate eating habits.

During testing at the UC Davis Bodega Marine Laboratory, abalone fed the new grape-waste diet grew at an unprecedented rate. According to Daniel Swezey, oceans and aquaculture director for the Kashia Tribe, the pomace-fed abalone grew three times as fast as control animals fed a commercial abalone diet.

A Circular Economy Win

This innovation solves two problems simultaneously:

1. Sustainable Feed Source: Grape pomace is an overwhelmingly abundant resource in wine-producing regions like Sonoma and Mendocino counties. Chemically, it is rich in carbohydrates and beneficial nutrients, similar to kelp.

2. Waste Diversion: The project provides a crucial end-use for winery waste. Recent state laws require wineries to divert pomace from landfills, where it decomposes and produces potent methane gas. Utilizing it as aquaculture feed is a significant win for the circular economy.

The next step for the research team is to refine the formula to be completely vegetarian. While current high-performing pellets still contain some fish meal, the long-term goal is to eliminate all animal ingredients, aligning the feed with the abalone’s natural herbivorous diet and further enhancing the sustainability profile of the operation.

The Kashia Tribe is currently moving forward with permitting and fundraising to build the farm, aiming to establish the first-ever abalone aquaculture facility run by Indigenous people. If successful, this grape pomace feed model could transform abalone farming in the U.S., proving that agricultural byproducts are a powerful, high-performance option for the future of sustainable aquaculture feed.