THE SAVORY SWIMMER SWIMS NORTH: A NORTHERN RANGE EXTENSION OF THE BLUE CRAB CALLINECTES SAPIDUS?

Worldwide, climate-change is shifting species distributions poleward. Here I present recent (2012-2014) observations of the blue crab, Callinectes sapidus Rathbun, 1896, in the Gulf of Maine (GoM), north of its historical range of Cape Cod, Massachusetts. To test the hypothesis of a climate-driven range expansion, I examined near-surface ocean temperatures. On average, ocean temperatures in the GoM in summer 2012 and 2013 were up to 1.3 degrees C higher than the average of the previous decade, suggesting that warmer waters may have promoted the recruitment of Callinectes sapidus to the GoM. Previous ephemeral populations of Callinectes sapidus in the Gulf of Maine have been reported since the 1860s. Recent observations and continued warming in the northwest Atlantic may signal a permanent poleward expansion of Callinectes sapidus into the GoM. If so, then a key goal for ecologists and managers will be to understand the effect of Callinectes sapidus on GoM food-webs and fisheries.