Economically important marine species face high climate risks

Dungeness crab, Pacific herring, and red abalone are among the coastal species that appear most vulnerable to climate risks such as rising ocean temperatures, acidification, and deoxygenation. 

The susceptibility of these species to environmental stressors could have significant consequences for local economies and cultural traditions that rely on healthy fisheries.

Species vulnerability to climate risks

In a new paper titled “A Collaborative Climate Vulnerability Assessment of California Marine Fishery Species,” researchers have outlined which animals are most threatened by predicted changes in the state’s coastal waters. 

The study was led by Timothy Frawley, an assistant project scientist at UC Santa Cruz’s Institute of Marine Sciences and assistant professor at UC Davis’s Department of Wildlife, Fish, and Conservation Biology.

The research aims to assist the California Department of Fish and Wildlife (CDFW) in developing “climate-ready” management strategies for commercial and recreational fisheries.

By detailing how different species respond to environmental shifts, the team hopes to lay a foundation for policies that can better adapt to and mitigate climate-related challenges.

Economically important fisheries

“The results are striking,” said Frawley, who spent five years as a commercial fisherman before earning a PhD in marine biology. “Some of California’s most economically and culturally important fisheries are assessed as being among the most vulnerable to projected future environmental changes.”

For coastal communities, the threat goes beyond ecology – it touches on livelihoods. The iconic Dungeness crab fishery, for instance, delivers more than 8,200 tons annually, yielding over $45 million for local economies in a typical season. 

While this crab fishery remains robust, others have not fared as well. Red abalone, once generating an estimated $24 to $44 million in recreational value per year, has been off-limits since 2018. 

Meanwhile, Pacific herring in San Francisco Bay – once the basis of a thriving commercial fishery – have seen biomass drop by over 75%, forcing many fishers to abandon the trade entirely.

Shifting species in a warming climate

“While overall across the Northeast Pacific, a species like Pacific Herring may do OK, try telling that to a herring fisherman based out of San Francisco Bay. If their resource moves hundreds of miles away, it’s a big deal to them,” Frawley explained. 

“It’s important to do these assessments at a scale that provides results that will be practical at the local level. So in that respect, this represents a step forward.”

Such local-level nuance is crucial, since some species may simply relocate northward as waters warm. For example, market squid – currently a mainstay of the state’s fisheries – could shift offshore or to cooler regions off Oregon or Washington, undercutting California-based fleets. 

By contrast, certain warm-water fish like Pacific bonito might expand their range into the California Current, potentially offering new fishing opportunities.

Species’ sensitivity to climate risks

To determine which species face the greatest climate risks, the study evaluated 34 fish and invertebrates for their vulnerability over two periods: 2030-2060 and 2070-2100. 

The researchers focused on both sensitivity (biological attributes such as reproductive rates, habitat preferences, and susceptibility to acidification) and exposure (projected ocean conditions, including temperature, salinity, upwelling, subsurface oxygen levels, and sea-level rise).

These factors were combined to rank species into four categories – blue (lowest vulnerability), yellow, orange, and red (highest vulnerability). 

Dungeness crab, red abalone, Pacific herring, pink shrimp, and Pismo clam were among those ultimately placed in the red zone over the longer term, with ocean acidification, sea-level rise, and other compounding challenges expected to intensify.

Red abalone and a changing coast

Among the most concerning examples is red abalone, a bottom-dwelling mollusk highly susceptible to marine heatwaves. Because it has limited mobility and depends on stable kelp habitats for food, any extreme temperature swings or shifts in ocean chemistry can devastate its populations. 

The fishery’s closure in 2018 was a stark indicator of how vulnerable benthic species can be, and the new study reinforces the urgency of monitoring and protective measures.

Market squid, contributing an estimated $43.9 million annually, and spiny lobster, worth around $10.7 million, also show cause for concern. Ensuring that these high-value fisheries can adapt may require both policy interventions and collaborative planning with industry stakeholders.

Supporting coastal communities

“My experience working as a fisherman has inspired me to focus my work as a marine scientist on supporting coastal communities by providing them with information required to better navigate risk and uncertainty,” Frawley said. 

“My time at sea impressed upon me the links and feedbacks between environmental variability and change and marine-resource-dependent industries and communities, as well as an appreciation for fisheries as a team sport.”

Though the public often views fishing as fiercely independent, Frawley explained that it requires a complex network. 

“To make the gears turn, it requires a team of individuals working together on deck, groups of boats sharing information; dock workers and truck drivers to unload and transport the product; buyers and processors to package and market it; and managers and scientists to set the harvest levels and ensure that operations are sustainable.”

Anticipating changes to protect fisheries

In highlighting the most at-risk species, this study provides a vital roadmap for the California Department of Fish and Wildlife as it works to develop adaptive measures.

Possible strategies include flexible harvest regulations, real-time monitoring of populations, and broad collaboration among scientists, fishers, and policymakers.

While shifts in ocean conditions are already underway, the ability to anticipate change is essential for managing fisheries so they remain viable in the decades to come. 

With clear evidence that climate change is already reshaping marine environments, proactive planning could mean the difference between a future of thriving coastal economies or dwindling opportunities for fishermen and seafood lovers alike.

The research was conducted in close collaboration with fisheries scientists at the National Oceanic and Atmospheric Administration (NOAA), the Nature Conservancy, and the California Ocean Protection Council.

The study is published in the journal PLOS Climate.

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