As ocean acidification threatens the shellfish industry, this California oyster farm is raising oysters resistant to climate change

Forward-thinking Carlsbad Aquafarm also diversifies into seaweed to develop vegan products

Despite the dangers to shellfish posed by ocean acidification, Carlsbad Aquafarms in California is producing oysters resistant to climate change and diversifying into seaweed production. Photos courtesy of Carlsbad Aquafarms.

Sitting on the California coast north of San Diego, Carlsbad Aquafarm has been farming oysters and mussels since 1990. Its longevity is impressive, partly because running a successful aquaculture operation in the Golden State can be notoriously difficult.

“There’s a lot of regulatory hurdles that California has that other states don’t have,” said Thomas Grimm, CEO. The permitting process can be challenging and lengthy, he noted.

That observation was echoed in a public commentary by Brandon Barney, co-founder of Primary Ocean. He stated in January that gaining state regulatory agency approval for a seaweed farm took years despite the project being backed by the U.S. government. And a 2019 study from the libertarian Pacific Research Institute found California ranked second to last among states in terms of its business regulatory environment.

“In California, there are a lot of reasons why it’s difficult to do aquaculture,” Grimm concluded.

There are also unique challenges that come with oyster farming in the time of climate change: As the ocean absorbs carbon dioxide at an alarming rate, ocean acidification is transforming marine ecosystems. Shelled animals, like zooplankton, corals, clams, mussels and oysters, cannot grow their shells in the acidic water and the effects are especially severe at the juvenile stages.

A commitment to doing things right and sustainably plays a role in the innovations Carlsbad Aquafarm is pursuing. One is the raising of oysters more tolerant to the increasing acidity of ocean water brought about by climate change. The oysters are also more resistant to disease and generally hardier than other commercially raised shellfish.

In conjunction with University of Southern California researchers, the project is an aquaculture implementation of a technique used in agriculture: the concept of hybrid vigor. This method involves the in-breeding of specific lines to heighten differences between groups of plants or animals, followed by the crossing of those lines with one another. The crossed off-spring are then crossed again, resulting in a hybrid animal or plant more robust than any of the original starting stock. The research project is ongoing but the early results are promising, Grimm indicates.

This hybridization requires raising successive generations, with the time for each generation in the sequence determined by how long it takes to go from a newborn spat to a mature animal. Consequently, there is a premium in having oysters mature quickly.

That compressed timeframe arises from several factors, according to Grimm. The water flowing through the lagoon where Carlsbad Aquafarms is located is rich in the calcium carbonate oysters need to build their shells. The water is also nutrient-dense, a result of a high concentration of nearby organic farms and fresh seawater from the adjacent ocean. A third factor is a steady, temperate climate that allows the oysters to grow year-round.

Hank Hogan, Global Seafood Alliance, 7 March 2022. Full article.

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