Reviving an Ancient Bond, with Grape Leftovers

Once, red abalone crowded the Northern California coast so thickly that, at some stretches, wading into the water almost invariably meant stubbing your toe against their soup bowl-sized shells. So the old stories say.

These days, however, populations of the marine snails have declined so much that the state forbids even recreational anglers from harvesting them. The main reason: Kelp, the seaweed that abalone feed on, has all but disappeared in the region. 

There isn’t even enough left to start raising abalone in captivity. 

But now the Kashia Band of Pomo Indians of Stewarts Point Rancheria in Sonoma County may have found a solution to at least this last dilemma.

With practical support from California Sea Grant, the Tribe recently conducted successful tests feeding abalone something that is uber-abundant throughout the region: grape pomace, the pulp that remains after winemakers press grapes. The experiments showed promising results. Abalone that ate feed containing the fruit leftovers thrived, says Daniel Swezey, the oceans and aquaculture director for the Kashia Band of Pomo Indians. “We were very impressed.”

A Cultural Cornerstone

Abalone have been a critical component of the culture of the Kashia for millenia. The Kashia people have a recorded history on the Sonoma Coast spanning 12,500 years, and since time immemorial, abalone shells have been used in Kashia ceremony. The meat of the abalone has also been a staple traditional food for as long as anyone can remember. Stories of abalone are connected to the stories of the origin of the Kashia people themselves.  “What I tell everybody, abalone is just as important to us as the buffalo is to the Plains Indians,” says Severino Gomes, a Kashia elder and the Tribe’s economic development committee chair. The shell of a large abalone can exceed 12 inches and yield over a pound of meat. The Kashia and other Indigenous people used to selectively pry them off rocks with special tools when the animals were more abundant.

Abalone are charismatic animals, says Swezey. “When you find a big abalone in the wild, they have this force and energy to them. They'll look at you with their eyestalks and you can feel that you're in the presence of a very powerful, interesting creature that is slower and experiencing the world differently.” 

When the state of California and the U.S. federal government began forcibly relocating the historically coastal Kashia people to distant reservations beginning in 1856, the Tribe began to lose access to abalone. “For more than 150 years since then, the Tribe has had to ask permission from newly arrived private land owners to access the coast and harvest resources that have always supported the Kashia people”, says Swezey. 

This made the idea of farming the snails using landbased aquaculture appealing. Gomes first heard about this concept as a young man in 1968. He immediately thought, “It would be great if the Kashia could have something like that.” 

Yet he didn’t think it possible. “We didn't have the land” for it, he says. “It was like dreaming of going to the moon.”

Land Returned, Kelp Vanished

In 2015, the Kashia, in partnership with the Trust for Public Lands, reacquired 678 acres of their ancestral property in Sonoma County, including a one-mile stretch of the Pacific Coast. That same year, a multi-year marine heatwave and an explosion of kelp-eating purple sea urchins (Strongylocentrotus purpuratus) wiped out much of the kelp in the area. Overall, more than 90% of kelp forests in Northern California vanished. With them, much of the abalone. 

Theoretically, the Kashia now had the land and the means to open an abalone aquaculture farm. Not only would the farm allow the Tribe to hang on to its traditions, but it could also help restock wild abalone populations in Kashia's territory. “The farm could produce many thousands of abalone destined for wild restoration, supporting efforts the Tribe and partners are leading to bolster the declining population, including efforts to rebuild local kelp forest,” says Swezey. But “a big critical question was, if the kelp is gone, how are we going to feed these animals?” 

There was one idea previously explored in the scientific literature. In Australia, researchers had tried feeding other abalone species the grape waste from vineyards. “In Sonoma and Mendocino County, there are unlimited wineries in all directions and unlimited grape pomace,” says Swezey. “I think everyone recognized quickly that we should take a look at it.”

The tribe approached Christopher Simmons, a food scientist at the University of California, Davis. “My initial reaction was a mixture of curiosity and intrigue,” he recalls. “One expects that abalone have never encountered a grape, much less the grape byproducts from winemaking.” 

On the other hand, grape waste mostly contains carbohydrates — just like kelp — along with other beneficial nutrients such as polyunsaturated fatty acids.

A Perfect Pellet for Spiky Tongues

The Kashia enlisted Luke Gardner, a California Sea Grant extension specialist based at Moss Landing Marine Laboratories who specializes in aquaculture. In 2023, with funding from the National Oceanic and Atmospheric Administration and grape waste from UC Davis's experimental winery, Gardner and his technician, Devin Fitzgerald, set out to craft grape pomace pellets that abalone might eat. 

The process took months. After milling the grape pulp into a powder, Gardner’s team mixed it with other ingredients, squeezed it through an extruder and baked it into a version of the dry kibble that many pet cats and dogs eat — but with a crucial difference.

Abalone prefer to eat at night, and they take their time. Pellets may sit in their tanks for days as the snails slowly scrape at them with their spiky tongues. 

This meant that the pellets needed to hold their shape while submerged. "There was a lot of 'wow, that didn't work, let's try this,'" Gardner says. He compares the process to a novice baker who wants to make pie but doesn’t have a recipe. “Your crust didn't stick together or it was too doughy. You move the proportions around, try different binders, all the while staying within the confines of your diet profile, which is this much protein, this much lipid, this much carbohydrate.”

Several diets were tested with grape pomace inclusion up to 24% as its main ingredient, along with smaller proportions of lupin flour, seaweed meal and flax seed oil. During testing conducted at the University of California, Davis Bodega Marine Laboratory, Swezey fed one group of abalone the grape waste food and fed another group a commercial abalone feed he found on the market. The grape pomace-eating abalone grew “three times as fast” as the control animals fed the commercial feed, he says.

A Solution to More Than One Problem

Currently, the best performing experimental pellets still contain some fish meal, matching the commercial feed of the control group. But Swezey hopes to change that. “The Tribe feels it's a little strange to be feeding fish to abalone because abalone are herbivores,” he says. “It's something we're trying to improve in the next round: Can we formulate these feeds without any animal ingredients?”

If the grape pomace feed continues to prove successful, it could be a win in more than one respect. The U.S. currently lags far behind other countries when it comes to farming abalone, which are considered a delicacy across much of Asia, creating an estimated $1.2 billion annual market for these snails. 

Meanwhile, California vineyards are increasingly desperate to get rid of their grape waste. Every pressing leaves behind about a fifth of the fruit, mostly stems, skins and seeds. A 2021 state law means that wineries now have to pay to dump this waste, a measure meant to keep grape pomace out of landfills, where it rots and produces methane, a major heat-trapping gas. 

But for the Kashia, grape pomace would mostly mean blazing a path to their own abalone farm — the first-ever run by Indigenous people. The Tribe is currently applying for the necessary permits and fundraising to build the farm. 

Earlier this year, their aquaculture efforts already bore fruit when Swezey and Kashia staff harvested several abalone raised as part of the Tribes aquaculture work to support a Kashia community gathering. “The Tribe has a big community event every year to celebrate the summer season,” Swezey says. “We harvested some of the animals we've raised for this occasion to let the community know that the Tribe has been making progress. The animals are very important, especially to elders.”