Joy to the world! San Francisco’s markets and menus are stocked with Dungeness crabs. It’s good news for everyone who loves the delicious decapods, as well as the crab fishery, one of the state’s oldest and most valuable commercial fishing groups.
“Here in San Francisco and other ports from Bodega Bay and to the south, commercial fishermen have been able to bring thousands of pounds of Dungeness crab to market,” Noah Oppenheim, executive director of the Pacific Coast Federation of Fishermen’s Association, said at a joint California legislative hearing held in San Francisco last week.
But the good news isn’t shared by our northern neighbors. The California commercial Dungeness crab season remains closed north of Bodega Head State Marine Reserve due to high levels of domoic acid. The toxin is related to a “bloom” of naturally occurring phytoplankton, called Pseudo-nitzschia. When crabs eat prey that have ingested the algae, they become contaminated and can impact birds, marine mammals and humans.
San Franciscans may remember when a historic bloom of unprecedented size and duration significantly delayed our 2015-16 Dungeness crab season.
That season also marked a spike in whale entanglements. Unusually warm, nutrient-poor waters pushed marine animals closer to shore for feeding. When the crab season finally opened, parts of the California coast became more crowded. Lines and pots wrapped around fins and flukes causing whales significant pain, injury and sometimes death.
To their credit, California policymakers and fishermen were quick to respond. Since 2015, they have worked with researchers and environmental groups to mitigate risks to whales. The San Francisco hearing was a chance to listen to the latest efforts. New and developing technology, such as breakaway and rope-less fishing gear, were floated as opportunities to protect whales and Dungeness crab fishermen. Director Chuck Bonham also announced that the California Department of Fish and Wildlife is seeking federal authority to reduce risks to whales.
But a more comprehensive response requires policymakers to address damaging levels of domoic acid. While increased temperature appears to be the dominant factor, other reasons, such as water pollution, contribute to the problem facing fishermen and whales.
“The Pacific Ocean is changing – it’s sick,” North Coast Senator Mike McGuire, who convened the hearing with Assemblyman Mark Stone, said.
No one in attendance disputed the sad sentiment. Warmer temperatures, driven by climate change, are destabilizing the ocean. Not only are they pushing marine life closer to shore and increasing dangerous run-ins between humans and whales, but they also contributed to the historic 2015-16 Pseudo-nitzschia bloom.
Scientists generally agree the algae grows faster in warm water. The waters north of San Francisco have been warmer than usual over the past several years. The increased temperature contributes to incidences of harmful blooms.
But temperature is only one part of a larger story.
“We can’t dismiss other reasons; too many policymakers are focused simply on temperature” Dr. William Cochlan, a domoic acid and phytoplankton researcher at San Francisco State University (SFSU), told me. “For a bloom to occur you need more than just warm temperatures, you also must have nutrients and adequate light. Pseudo-nitzschia is getting those nutrients, in part, from sewage and agricultural sources.”
Earlier this year, researchers at SFSU published a seminal study linking nutrients in wastewater pollution to more damaging blooms of the phytoplankton. It uses ammonium and uria, forms of nitrogen in water discharged from wastewater treatment facilities or running off ranches and farms. According to researchers, pollution from these sources makes the phytoplankton more toxic than natural sources of nitrogen.
This is vital information for policymakers, fishing groups and environmentalists, who are already actively working to address whale entanglements and adapt to climate change. In addition to better fishing gear, protecting the Dungeness crab fishery and whales into the future may require increasing wastewater recycling and imposing lower ammonium discharge requirements.
“I think the future is a vision where crab stays on our holiday menus forever, coastal communities are thriving and resilient, and we can all look westward and see whales and turtles swimming free from the risk of entanglement,” Bonham said.
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Robyn Purchia is an environmental attorney, environmental blogger and environmental activist who hikes, gardens and tree hugs in her spare time. She is a guest columnist. Check her out at robynpurchia.com Bay Area News