Center for Coastal Studies

Right Whale Migration Update: April 9, 1997

Greetings from Stellwagen Bank National Marine Sanctuary -- This April has certainly provided us with some quirks from Mother Nature -- an April Fool's Day blizzard in eastern Massachusetts, followed by a series of warm, coat-free days of rapid melting (but no flooding unlike other parts of the country). I saw my first robins (3) on Easter Sunday, March 30 and dozens of them this last Sunday (April 6), so I guess the snow didn't scare them off.

Although the robins seem to be settling in for the summer, the right whales are still on the move. The New England Aquarium's right whale group in Florida reports that they have wrapped up this year's program. Their last week and a half of flights (March 18-31) did not produce any additional sightings. The final tally for the 1996/1997 season was seventeen new calves. Of the three mother-calf pairs spotted in Cape Cod Bay to date, it is believed that at least two pairs were seen down south earlier in the season. The group's last sighting, on March 18, was that mother and calf that tracked from Amelia Island down to Daytona and back to north Brunswick. Says Lisa Conger, "She apparently decided to take one last look at the Florida coast before heading north."

Have any of you been able to answer my challenge question of several weeks ago about right whale travel times -- it was a bit of a tricky question since I mixed statute miles and nautical miles. I asked how long it would take the whales to travel the 1,200 miles from Florida to northern feeding grounds if they move at a rate of 20-30 nautical miles a day. Since they are traveling in a south-north direction, each minute of latitude equals 1 nautical mile which equals 1.15 statute mile. To change 1,200 statute miles to nautical miles you divide by 1.15 and get an answer of 1,044 nautical miles. If the whales travel 20 nautical miles a day, it will take them 52 days. If they speed along at 30 nm per day, it will only require 35 days of swimming. Therefore, if all the whales left Florida by March 18, we should be seeing many more of them in the Gulf of Maine in the not too distant future.

Unfortunately, the scientists have observed a disturbing sight -- a bloom of the red alga Phaeocystis in Cape Cod Bay. Corresponding with the algal bloom has been a disappearance of the right whales from the Bay. Usually the right whales stick around, feeding on zooplankton -- and, in particular, copepods -- until mid-April before heading out to the Great South Channel.

Charles "Stormy" Mayo, chief scientist from the Center for Coastal Studies (and famous to those of you who have used The Voyage of the MIMI curriculum) has been studying right whales and their feeding behaviors in Cape Cod Bay for over 13 years. He says that this has been a very different sort of year -- with earlier first sightings, earlier concentrated sightings and an earlier departure. The first two mother-calf pairs appeared well before the previous record. He has also noticed little surface feeding (usually a fairly common sight in Cape Cod Bay). The researchers have found that zooplankton concentrations have been considerably lower than normal, with only one spot registering a high enough copepod concentration to elicit feeding according to Stormy's mathematical model.

Stormy hypothesizes that this change of behavior may be caused by the "nuisance alga" now filling the water. Although a regularly reported species, Phaeocystis has been found in what seems to be uncommonly high numbers this spring (and is lasting later into the season than in past years). The alga lives in large jelly colonies that can be 1 millimeter in diameter -- with counts of up to 15 colonies per milliliter of water found this season. This dense concentration of cells may have a detrimental effect on diatoms and other plankton (and consequently, the copepods that feed on them). Without the copepods, the right whales have no reason to stay in Cape Cod Bay -- and that's what seems to have happened. Boat and aerial patrols this past weekend reported no right whales in the Bay, although some significant concentrations were seen at a location called Wildcat Knoll some 30 miles northeast of the Bay (11 whales) and in the Great South Channel southeast of outer Cape Cod (4 whales).

Stormy Mayo believes that a thermal front (an area where two water masses of different temperature meet) at Wildcat Knoll may be a regular seasonal oceanographic feature. The satellite images taken this year are remarkably similar to last year's pictures. According to Stormy, this thermal front may be a regular residency area for right whales that had not been recognized in the past (fronts are often areas of dense plankton concentration).

Stormy is also very interested in another aspect of this rapid and persistent red alga phytoplankton growth. Phaeocystis is believed to bloom in response to nutrient imbalances in the water. Some scientists have expressed concern about a sewage outfall pipe that will begin discharging treated wastewater into Massachusetts Bay next year. They, including Stormy, believe the nitrogen in this wastewater may encourage further plankton blooms and may change the concentrations of different phytoplankton and zooplankton species in Massachusetts and Cape Cod Bays. Since we don't understand what is happening this year, it will be hard to determine what changes are natural and what are man-made once the outfall pipe starts discharging. Other scientists say that these blooms occur naturally and that the amount of nutrients entering the system from the future outfall pipe may not have a significant effect. Obviously, there is very little consensus here and much at stake.

Hope the rest of April is sunny and pleasant. I'll have a new right whale report for you on April 23rd. Until then, this is Anne Smrcina, education coordinator of the Stellwagen Bank National Marine Sanctuary, signing off.

Try This!
Take a close look at the tiny creatures that live in a nearby pond, lake, river or ocean. The diversity of life may surprise you.

1. Collect samples of water from at least 2 different sources. (Students may want to bring samples from home, for more diversity.)
2. Using a hand lens or microscope, look closely at the plants and animals in each sample. According to Anne Smrcina, right whales feed on copepods, a zooplankton of the ocean food chain. The tiny plants and animals you see in your water sample form the base of the food chain where you collected your sample.
3. Sketch each of the creatures you see. Identify them by name, if you can. Or name them yourself, with descriptive names that fit their appearance or behavior.
4. Devise a way to estimate the density of one of the creatures in your water sample.

Discussion Questions

• Were any of the creatures found in all water samples?
• Which sample contained the most diversity? The least? Why do you think so?
• What was the density of the most common creature in each sample?

The Next Right Whale Migration Update Will be Posted on April 23, 1997.