San Francisco’s love affair with Dungeness crab grows more toxic

For local Dungeness crab fishermen and women, life has become a heart-shaped box of Valentine’s Day chocolates — it’s hard to know what they’re going to get. While ocean conditions are reportedly stellar this winter, the industry lost millions when a toxic algal bloom significantly shortened the 2015 season. Seasons were postponed again in 2016 and 2017.

“The situation in the crab fishery is totally chaotic,” Noah Oppenheim, executive director of the Pacific Coast Federation of Fishermen’s Associations, told me.

Last week, Congress showed commercial crabbers some love. The federal budget bill allocates $200 million in relief to fisheries impacted by disasters, including the local Dungeness crab fleet. This money will sweeten the lives of families dependent on the decapods. But warming waters and drier weather promise bitter days ahead.

From left, San Francisco State University researchers Dr. William Cochlan, Maureen Auro and Regina Radan conduct incubation experiments with toxic microalgae off the Washington coast. (Courtesy San Francisco State University)

Climate change isn’t the only threat to our beloved Thanksgiving feasts, though. According to a new study published by researchers at San Francisco State University, wastewater pollution also makes our relationship with Dungeness crabs more toxic.

Waste doesn’t disappear with a flush. In San Francisco, wastewater from homes and streets drains to treatment facilities operated by the San Francisco Public Utilities Commission. The facilities clean the water according to federal and state standards. But a form of nitrogen, called “ammonium,” remains when SFPUC releases the water into the Bay and Pacific Ocean.

Unfortunately, ammonium takes a toll on marine life. Pseudo-nitzschia, the toxic algae responsible for closing most of the 2015 commercial Dungeness crab season, uses ammonium and other forms of polluted nitrogen runoff. According to researchers at S.F. State, exposure to this pollution makes algae much more toxic. When crabs eat prey that has ingested the algae, they become contaminated and can impact birds, seals and even us.

“The reduction of ammonium loads into coastal water would be a good thing for the environment,” study co-author Dr. William Cochlan, a research professor of biology at S.F. State, told me.

A chain of cells of the toxigenic diatom Pseudo-nitzschia multiseries (pen-like in shape) next to four toxic dinoflagellates of the Alexandrium genus. Both microalgae species produce potent neurotoxins and are found naturally off the shores of California. (Courtesy B. Bill/National Oceanic and Atmospheric Administration)

Of course, scientists expect carbon emissions associated with climate change to also play a significant role. Normally, ammonium doesn’t stick around the ocean for very long. But as the ocean absorbs more carbon dioxide from the air, it loses oxygen and becomes more acidic. This allows ammonium to persist longer and at higher concentrations, likely making toxic algae blooms more frequent and dangerous.

While San Francisco is already a leader when it comes to reducing carbon emissions, we’re not making many national headlines for reducing wastewater pollution. According to a recent report, SFPUC’s Southeast Treatment Plant discharged more overall ammonium into the Bay than other Bay Area municipal facilities in 2016-17. The Oceanside Treatment Plant also does not remove ammonium before it’s sent to the Pacific Ocean.

The SFPUC has started constructing a recycled water plant, which will use treated water from the Oceanside Treatment Plant to keep Golden Gate Park, Lincoln Golf Course and the Presidio Golf Course green. Recycling water will lower the annual volume of wastewater discharged, but will not reduce the amount of ammonium.

“Removing ammonium and/or nitrogen from the effluent would require adding entirely new treatment processes,” Idil Bereket at the SFPUC told me.

This is disappointing news for Dungeness crab lovers, but it’s not the end of the story.

San Francisco and other Bay Area municipalities are funding new research related to harmful algae. While work is currently limited to algae within the Bay, researchers expect to explore its impacts in the ocean in the future.

Normally, analysis is a poor substitute for action. But in this case, more research is critical. Scientists are still struggling to understand all the components behind the 2015 Dungeness crab season disaster, and funding is hard to find. That’s why the recent S.F. State study is so useful: It provides more data and can reduce the chaos fishing fleets face.

“It behooves us to do more studies like that,” Dr. Clarissa Anderson, who is working on a toxic algae bloom forecast system, told me. “It helps us tease out what the future may look like as we put more waste in the water and more carbon dioxide in the air.”

Imagine a life that isn’t like a box of chocolates. While it would help to reduce the number of bitter bites in the box, with a little research, San Francisco’s fishing industry may better predict what it’s going to get.

“Are individual Starburst candy wrappers compostable?”
— Elena Young

In this case, satisfying your sweet tooth may not satisfy the planet. Recology, San Francisco’s recycling company, didn’t have an answer. I was told the colorful paper wrappers could have a plastic coating. The manufacturer, Wrigley Company, also wouldn’t give me an answer. They only provided a generic response about the company’s environmental efforts.

A Google search reveals numerous ways to turn individual Starburst wrappers into wallets, bracelets, dresses and shoes. But if you’re short on time, it looks like the colorful paper belongs in the black bin, not the green or blue. Of course, oranges and bananas have a fruity flavor and a compostable wrapper.

I’ll keep investigating. In the meantime, email more questions to

Robyn Purchia is an environmental attorney, environmental blogger and environmental activist who hikes, gardens and tree hugs in her spare time. Check her out at

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