Signal Crawfish

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Crawfish. Crawdads. Crayfish. Mud bugs.

In this country, these little freshwater lobsters go by many names, and when you consider that there are more than 330 species of crawfish native to the United States, it’s no wonder we can’t agree on what to call them.

The species we typically associate with the name crawfish – think massive boiling stockpots in Cajun country – is the red swamp, or Louisiana, crawfish. In many parts of the country, these little guys pose their own problems as an invasive species, but where I am, in Northern California’s Sacramento Valley, the primary quarry is the signal crawfish (Pacifastacus leniusculus) a distant, but equally delicious, relative of the Louisiana species.

Signal crawfish get their name from the bright turquoise or white patch at the joint of their claws, a marking reminiscent of the “signal” flags used by train conductors back in the day. Compared to other species of crawfish, signals are incredibly adaptable, and have been shown to tolerate a wide range of water temperatures, pH levels and even salinity.

While these traits make the signal an incredibly hardy stock for commercial crawfish operations – of which there are now many, primarily in their invasive range – they’ve spelt nothing but trouble for local fauna.

Their introduction to California waters has brought about the end of almost all of the state’s native populations, so much so that the critically endangered Shasta crawfish is now the only remaining species endemic to the waters of the Golden State.

Native populations in Europe and Asia have been similarly decimated.  

In the 1960s, following a crawfish plague that decimated stocks of the native European crawfish, the signals were imported to Sweden and Finland to help satisfy the massive Scandinavian appetite for the critters. Efforts to contain the signals to purely commercial operations failed miserably, and before long the voracious species was loose in rivers and streams, outcompeting the smaller and less adaptable native populations. To make matters worse, the signal crawfish is also a carrier of the aforementioned crawfish plague, and its spread has had devastating effects across Europe and Asia.

Less than 60 years after its introduction, the signal crawfish is now one of the most widespread aquatic invasive species on those continents.

In the kitchen, the signal crawfish is a much more welcome visitor.

We all know about the classic Louisiana-style boil, and while the results here are almost always excellent, the crawfish shouldn’t be limited to just one means of preparation. Bearing a rich, sweet flavor similar to that of their larger saltwater relatives, these little freshwater lobsters are an adaptable ingredient that can be substituted into most any shellfish recipes.