Dungeness Crab Off the Menu as Toxic Algae and the ''Warm Blob'' Battle

Dungeness crab trap.

A battle exists among some crab lovers about the delectability of the Dungeness from the West Coast and the Chesapeake blue crab from the East. (The debate has even invaded the Ecocentric office as of late). Alas, a taste test between the two iconic shellfish has been indefinitely postponed because Dungeness is off the menu.

The reason there is no Dungeness is the weeks-long delay to the opening of its harvesting season due to toxic acid buildup in the crabs that make them unsafe to eat (especially crab "butter"). From California up through Oregon to Washington State, officials have detected high domoic acid levels in Dungeness, rock crabs and other marine creatures. Domic acid is a neurotoxin produced from naturally occurring algae called Pseudo-nitzschiaa that can make people dizzy and vomit if consumed. If enough of the algae is ingested, it can cause amnesic shellfish poisoning leading to memory loss, seizures and even death.

Since the toxin can't be removed by cooking or freezing shellfish, levels must drop in the natural environment before the shellfish can be eaten. There are indications that this is happening, giving crabbers hope that all areas will be open for harvest by the end of December.

Warm Blob Meets Toxic Algae

The widespread domoic acid contamination along the West Coast is the result of an enormous algal bloom that has spread offshore from California to Alaska. The toxin has disrupted the food chain as high levels of domoic acid have accumulated in razor clams, which the Dungeness crabs eat and take up the toxin in the process. Other marine creatures have been negatively impacted, too. At least 240 sea lions have died in California from poisoning, according to alarmed scientists who say that the marine mammals eat large quantities of feeder fish like anchovies that have ingested the algae.

This giant algal bloom coincides with an equally giant "warm blob" of water - spanning 1,000 miles and 300 feet deep - sitting in the Pacific Ocean off the West Coast.

This giant algal bloom coincides with an equally giant "warm blob" of water - spanning 1,000 miles and 300 feet deep - sitting in the Pacific Ocean off the West Coast. Some scientists hypothesize that the warm water might have supercharged the natural growth of the algal bloom and made it run rampant. This complicated battle about what has caused the algal blooms, whether it's the warm blob or another important meteorological event, such as the twins El Niño and La Niña, makes it hard to know the precise conditions that are winning out..

What is known is that warmer water in the Pacific has not only harmed crab and other shellfish populations because of the toxic algae, but has disrupted West Coast fisheries as a whole. Certain fish are no longer in abundance like they once were as they move north from warmer to cooler waters. This apparent trend of warm water disrupting the balance of ocean chemistry and shifting marine species habitat, spawning and migration patterns is consistent with climate change, as experts at the IPCC (Intergovernmental Panel on Climate Change) have found.

These concerns about higher ocean water temperatures and fisheries, while caused by large-scale processes, are things that must be understood by everyone from public officials to scientists, fishers to seafood shoppers. Without acknowledging the likelihood of more toxic algal blooms and more shifts in what fish and shellfish are around for us to catch and eat, we are just hurting ourselves. Yes, grand global events like the successful conclusion of the COP21 climate talks are necessary to achieve sustainable solutions on the complicated battle between climate change, warm blobs, algal blooms and sustainable fisheries, but our personal knowledge understanding and choices  about how these complex issues work make prepare the way for those bigger efforts like fighting climate change and reducing overfishing possible.

That way, Dungeness crab might be on the menu for those smaller, friendlier battles like the crab taste test.


Image "Dana" by roseannadana on Flickr used under a Creative Commons Attribution-NoDerivs 2.0 Generic license.