Work is underway to begin mapping the genome of the European green crab, one of the most successful invasive species currently causing chaos along the Pacific coast of North America, in a bid to gain better insight into the best approach to manage its populations.

It’s hoped that by mapping the genome of the European green crab, environmental workers will be armed with an understanding of how the species has so far been able to adapt to a variety of environments, including changing water temperatures along the Pacific coast.

Existing genetics research indicates that all the European green crab along the Pacific coast of the US and Canada originated from a single introduction event to San Francisco Bay from the northeastern United States. Across the state of Washington, the species has had severe impacts, particularly upon the East Coast shellfish industry where it has caused harm to important eelgrass and estuary habitats.

So prolific is the species, it has been listed as a ‘priority’ for the Washington Invasive Species Council and a top management priority for Washington Department of Fish and Wildlife, the state’s jurisdiction lead for aquatic invasive species. 

“The green crab is one of the most successful invasive species globally, and a large part of that success is its adaptability to a wide range of variable marine habitats,” said Emily Grason, marine ecologist and lead of the Washington Sea Grant Crab Team programme. “In Washington, we are likely to be managing European green crabs for a long time, so we will need every tool we can access to protect local shorelines.

“Mapping the genome is a very forward-looking effort to find and develop new management tools.”

To carry out the research, last autumn Washington Sea Grant received $185,000 in state funding to work with the Washing Department of Fish and Wildlife and the Woods Hole Oceanographic Institution to sequence the European green crab genome.

That work is now underway. But it isn’t easy – particularly for a species like the European green crab, due to the complexity of its genome. 

“Crustaceans like crab, shrimp, and lobsters have very complex genomes, and it is only with recent advances in sequencing technology that this research has become possible for them,” said Carolyn Tepolt, associate biologist with the Woods Hole Oceanographic Institution. “A high-quality genome is a critical scientific tool that will enable a much wider range of research into green crab biology and management.”

The research will not only have positive implications for European green crab management in Washington, but for the rest of the West Coast and anywhere in the world where European green crab may be impacting local ecosystems and industry.

Findings from the project will be summarised in a publication led by the Woods Hole Oceanographic Institution while the genome itself will be made publicly available on National Centre for Biotechnology Information’s GenBank – the standard for long-term public archiving of genomic data.

In early 2022, Governor Jay Inslee issued an emergency proclamation in response to growing populations of European green crab in Washington waters. As of 2024, European green crab infestations have been found along much of Washington’s Pacific coast as well as in smaller, localised detections in the Salish Sea.  

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