It’s not a name that trips off the lips: Calanus finmarchicus. But if you happen to be a North Atlantic right whale, it’s a name at the tip, so to speak, of your tongue. Calanus finmarchicus is a plump, fat-filled copepod that North Atlantic right whales eat by the ton when they visit the Gulf of Maine. Where there are Calanus finmarchicus, there will be right whales. And when the Calanus finmarchicus disappear, well, you can guess the result. 

This year right whales have been in the news for two reasons. The first is the unusual number of whales that have congregated in Cape Cod Bay for the past month or more. Of a population estimated at slightly more than 500 animals, more than 200 are cruising about Cape Cod Bay, causing consternation and dismay among Massachusetts lobstermen. Lobstermen are under strict regulations to prevent the whales from becoming entangled in their traps, which include a complete shutdown of the fishery from February 1 to April 30 each year. Because of the presence of whales, that closure was extended until mid-May.

The second newsworthy item is the fact that this has been a very bad winter for right whale births. Only four new calves have been identified by whale researchers. Right whale mothers typically give birth in winter in the warm waters off Florida and Georgia and then migrate with the calf to feed in the Gulf of Maine during the summer. Right whale births picked up in the late 1990s and 2000s, but since 2010 the number of new calves born each winter has taken a tumble.

That worries the National Marine Fisheries Service (NMFS). North Atlantic right whales are considered “depleted” under the Marine Mammal Protection Act and labelled as “endangered” under the Endangered Species Act. Through the latter Act, the NMFS has a regulatory obligation to make sure that no human actions jeopardize the continued existence of the whales or result in the “destruction or adverse modification of designated critical habitat” used by the whales. 

In its attempts to keep the right whales from going extinct, NMFS has required all sorts of changes in how lobstermen and other fishermen ply their trades, including requiring sinking line for lobster traps. Ships greater than 65 feet in length, such as container ships, must drop their speed to no more than 10 knots in areas where the right whales give birth and in areas where they are likely to feed. International shipping lanes have been altered. Whale-watching boats and other vessels cannot get closer than 500 yards to a right whale in order to reduce any stress such boats might cause the whales. 

But what NMFS can’t do is feed them. Right whales are baleen whales. They eat by gulping vast amounts of water containing tiny zooplankton into their pleated gullets and then forcing the water out baleen plates, thus leaving the food behind. They need a lot of calories to keep their multi-ton bodies going. So right whales will try to feed on zooplankton that give them the most calories per gulp: Calanus finmarchicus.

Calanus finmarchicus likes to live in cold (15o C) water and is found in huge abundance throughout the sub-arctic North Atlantic Ocean. In the Gulf of Maine it is at the southern extent of its natural range. Calanus finmarchicus used to be pretty happy here, as much as a 0.1-inch zooplankton can be happy. In the springtime, the Gulf of Maine blooms with life as phytoplankton take advantage of the strengthening sun and abundant nutrients in the water. These blooms provide Calanus finmarchicus with lots to eat and, like a glutton at a free buffet, it puts on weight in the form of lipids, i.e. fat. 

Since 2010, however, the number of fat and happy Calanus finmarchicus found in Wilkinson Basin have dropped by about 30%, according to Jeffrey Runge of the Gulf of Maine Research Institute. The Canadian Department of Fisheries and Oceans, which also monitors zooplankton abundance in the Gulf of St. Lawrence and off Nova Scotia, saw a similar decrease in Calanus finmarchicus

At about the same time, the number of right whales in their typical summer and fall feeding grounds off Grand Manan Island and in Jordans Basin also dropped. But right whales started showing up in Cape Cod Bay in previously unheard of numbers. Some looked skinny; many showed marks of having been entangled in fishing gear or struck by ship propellers. And fewer babies were being born.

So what is causing the right whale birth rate to drop? Is it that entanglement in fishing gear weakens the whales so that they haven’t the reserves to produce young? Is it that their preferred food has disappeared due to a warming ocean? Has the increase in rainfall and drop in the Gulf’s salinity levels due to climate change diminished the phytoplankton bloom that feeds Calanus finmarchicus? Or has the decrease in Calanus finmarchicus abundance in Canadian waters led to a corresponding decrease in the Gulf of Maine?

Research scientists at NMFS want to answer those questions yet the agency’s first and foremost responsibility is to ensure the continued existence of North Atlantic right whales. They cannot control the Earth’s climate nor the temperature of the Gulf of Maine. They can’t herd Calanus finmarchicus into neat pods for snacking on by right whales. They can, however, control the behavior of fishermen and others who use the ocean. And that, unfortunately, is what they will do if right whale numbers do not improve, and improve quickly.