15 September 2014

Right Whales Return and Disappear Again

It was with a great sense of relief that I read in early August that right whales had returned in large numbers to the Bay of Fundy. During the last week in July, whale watch boats out of Grand Manan counted 50 right whales. Comments ran along the lines of "just like the old days." Researchers from the New England Aquarium, who have been studying right whales in the Bay of Fundy for 34 years, documented 45 whales on Thursday of that week and another 30 or so on Friday.

This was good news, because last year, the NEAq team found five whales in the Bay, the lowest in all the years they have been going there. It was very worrying. The Bay of Fundy normally hosts the largest number of right whales of any place we know. I have seen as many as 75 on a single trip. That's quite a large number, about 15% of the entire population.

Right whales come to the Bay of Fundy in search of food. Summer is the time when plankton blooms in northern waters and many species of whale come to the Bay of Fundy looking for food. For many of them, this is the only food they will have all year. They survive winter on the fat they store during the summer. So in general, the whales go where the food is, and last year there was no food in the waters of the Bay of Fundy, at least not the kind of food that right whales eat.

Right whales consume a species of copepod, a very tiny, almost microscopic shrimp-like animal, named Calanus finmarchicus. Calanus is a cold water species. Increases in water temperature affect how early in the year they reproduce, how long they remain at the surface (right whales are surface feeders) and ultimately whether they reproduce at all. It is not much of a leap to speculate that the absence of Calanus in the Bay of Fundy in August of 2013 was due to higher-than-normal surface water temperatures.

Looking at data from NOAA weather buoys in the northern Gulf of Maine, near the mouth of the Bay of Fundy, I have found that the surface water temperature has been rising over the past decade, with 2012 and 2013 being the warmest on record. That might account for the absence of food and the absence of right whales.

This year is different. The water temperature is closer to what it was a decade ago. At first I thought that might account for the abundance of right whales, for the comment that it feels "like the old days." Surface water temperature tends to follow air temperature. So with global warming we expect to find warming of ocean surface temperatures as well, with obvious consequences for cold-water species. At first there was reason to celebrate the return of right whales to the Bay of Fundy this year, but there is now reason to remain concerned, because in spite of year-to-year variations that can be quite dramatic, the long-term trend is toward warming. And the right whales have disappeared again. That early optimism has been replaced with concern once again. Surveys in the Bay of Fundy, and in the Roseway Basin off the Coast of Nova Scotia have turned up very few whales. Five or six have been spotted off the coast of Cape Breton, farther north. Given what happened last year, I am not optimistic that the Bay of Fundy will remain a gathering place for right whales.

The question of the moment, at least for me, is what effect two years of poor food resource in the Bay of Fundy is having on the health of the population. It costs a lot of energy to go looking for food, not knowing where it will be found. The energy in the food that is found has to be higher than the energy spent to find it, or it is of no use. If the energy spent looking is higher than the energy in the food found, then right whale health will be decreasing and mortality from starvation could be high.

I have no evidence that right whales are starving to death, but I think it is a concern. What does the second year of absence of whales in the Bay of Fundy mean? Does it mean they got the word and are avoiding the Bay? Or does it mean last year's lack of food significantly diminished the population? A large number of whales appeared in Cape Cod Bay in April, suggesting that the population is okay, but their food is moving. But a lower-than-normal number of calves was born in the winter, suggesting the population is experiencing some difficulties.

Researchers have depended on the predictability of right whales' presence in the Bay of Fundy to monitor and study them and estimate their total numbers. They photograph them, count them, identify individuals, collect DNA and poop, and thus have gathered a very complete picture of the size and structure of the right whale population. If right whales have abandoned the Bay of Fundy, it will take significant human effort to figure out where they are going to find food, in order to continue to monitor their health and well-being.

If they drop off of our radar, we will have little idea how they are faring, except to continue to observe how many females appear off the coast of Florida in the winter to give birth, and perhaps to monitor them more closely in Cape Cod Bay in the winter and spring. Right whales have survived being hunted to near extinction. They have surely survived other changes in their food supply. We can hope and believe they are adaptable enough to survive this one. But it would be nice to know. Whale researchers don't seem to be very good at remaining dispassionate. It's not an easy job. You have to care a lot to go out every day in a tiny boat and spend long days searching for and documenting whales. The blog posts from the New England Aquarium convey real concern and a sense of loss.

Seeing the right whales each year is one sign that this precious Earth is still holding things together, despite all the stress it is experiencing at our hands. Not seeing them is very worrying, and for me feels like a sign that we are pushing the Earth beyond its limits and will be facing many more losses in the years to come.

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