Shellfish and Climate Change

Climate-related changes, such as warmer temperatures and a change in the chemistry of our oceans, will threaten our shellfish.

Ocean Acidification

What is Ocean Acidification?

Carbon dioxide (CO2) is produced every day and absorbed by the oceans. As CO2 reacts with seawater, it lowers pH and reduces the concentration of carbonate ions. Motor vehicles and other transportation-related sources produce CO2.

Impacts on Shellfish

Shellfish shells are less likely to form in an acidic environment, which compromises the future of this valuable high-protein, low-fat food source. The evidence of ocean acidification in the Pacific Northwest is compelling. Learn more from Ocean Acidification: From Knowledge to Action, Washington State's Strategic Response (PDF).

Harmful Algal Blooms and Marine Biotoxins

Harmful algal blooms usually increase during the warm summer months. As daily temperatures continue to rise, the number of days ideal for harmful algal growth increases. These harmful algal blooms produce marine biotoxins that are poisons. When molluscan shellfish eat the toxin-producing algae, the toxin remains in their systems, which can cause illness or death in humans and other mammals who eat the shellfish.

The more frequent and severe harmful algal blooms we see, the greater the risk that marine biotoxins will be present in shellfish, making the shellfish unsafe to eat.

New “Bugs” are Causing Illnesses

In 2011, illnesses caused by Diarrhetic Shellfish Poisoning (DSP) were found in Washington, making our state the first in the U.S. where tests confirmed DSP illness from shellfish. The algae that produces the DSP toxin has been detected in Washington's marine waters for some time, but it hadn't produced the toxin. Now the toxin is found throughout our marine waters on a routine basis.

As the planet's oceans warm, coastal regions are seeing more and more algae blooms, often worsened by fertilizer and manure that runs off from yards amd farms. These algae can close beaches, and the toxins released can poison shellfish and make people who eat the shellfish sick. With toxic algal blooms becoming more potent and lasting longer, scientists are taking a closer look at the links to a changing climate. What was once considered a summertime matter is now being considered a year-round issue.

Biotoxins Commonly Found in Washington's Marine Waters

Amnesic Shellfish Poisoning

Diarrhetic Shellfish Poisoning

Paralytic Shellfish Poisoning ("red tide")

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