Right whales measure up to 46 feet long and weigh as much as 70 tons—the bulk of their heads and their enormous jaws have allowed comparisons to gigantic hippopotamuses. The mammals travel as far down as Florida in the winters and as far north as Canada in the summer. In terms of power, Mayo compares the breaching whale to an 18-wheeler made of blubber.
Each winter and spring, roughly one third of the right whale population visits Cape Cod Bay and its environs, feeding on oily zooplankton for up to 20 hours a day. A confluence of circumstances—high water quality, the arm of the Outer Cape, currents, and other oceanographic characteristics—makes the concentrations of plankton found in the bay among the most abundant in the world.
The stagnation of the right whale population is perplexing. Unlike its counterparts—the southern right whale and the North Pacific right whale—decades of international protections and the demise of the whaling industry haven’t prompted a resurgence in the North Atlantic right whale population. Mayo believes this could stem from a connection between lower right whale calving rates and lower plankton abundance in Cape Cod Bay. Essentially, the whales might not be eating enough to sustain themselves.
During the research cruise, Mayo and company traverse between nine “stations”—sets of coordinates that PCCS has been visiting since 1984. Crew members drag mesh nets behind the boat to collect plankton samples. The pores in the mesh are one third of a millimeter wide to mimic right whales’ baleen, the filtering mechanism in their mouths that separates plankton from the water. Helical flow meters, which measure the amount of water passing through the mesh, are attached to the nets.
Clad in puffy exposure suits, research assistants Beth Larson and Christy Hudak take turns hauling the nets on board, collecting the plankton inside, and shouting the digits displayed on the flow meters to Mayo, who keys them into his laptop. Sarah Fortune, a former research assistant for PCCS and a student at the University of British Columbia, is developing a model using PCCS data that will attempt to predict how much food North Atlantic right whales need to meet their energy requirements. “By knowing what the whales are actually feeding on in the wild, we are able to compare what the model predicts they need with what we observe in the field,” Fortune says.
- Posted in Nature