#18 To Eat Or Not To Eat? That Is Not The Question.

As our field season slowly winds down, discussions of low right whale numbers in the Bay of Fundy continues. A particularly interesting theory has been recently suggested that relates to copepods, the primary food for North Atlantic right whales. A colleague informed us of an unusually warm slug of fresher water that moved into the Gulf of Maine earlier this year. What does warmer water in winter and spring mean for right whales in August - October? Potentially, A LOT!

Calanus copepods collected during our survey in Roseway Basin

In the Bay of Fundy, right whales feed specifically on a copepod species called Calanus finmarchicus that are found in dense aggregations at or near the bottom of deep water basins in late summer and early fall. The Bay of Fundy is one of the main feeding habitats for North Atlantic right whales so their absence here suggests something may be going on with the food resource on which they have traditionally depended. This brings us back to our original question - how could unusually warm water in winter affect right whales in the summer?

In the Bay, adult copepods spawn in late winter, early spring, just in time for the spring phytoplankton bloom. As copepods develop, they feed on the phytoplankton then as summer rolls around they begin a period of hibernation, where they descend to depth and remain there all winter until spring...and the cycle continues (click here for more detail on the copepod life cycle).

Zach and colleagues from Grand Manan Whale and Seabird Research Station sampling for copepods in the Bay of Fundy

For now we can only speculate to how the unusually warm water which apparently started to infiltrate in late winter may have affected the spring phytoplankton bloom and/or copepod recruitment. If copepod abundance was lower this year than traditionally found in the Bay of Fundy then the influx of warm water starting earlier this year may provide some insight as to why right whales did not show up in significant numbers. Future detailed monitoring of copepods in the Bay of Fundy would be a big step toward understanding right whale distribution and ecology.

Zach