MIGRATIONS To save the northern right whale, conservationists need to gather information on the health of the population as well as basic right whale biology. But in order to study the whales, researchers have to find them first. Such a task has proven difficult given the low number of whales and the enormous size of their range, and the tremendous distances they swim during the year. Although scientists understand the basic seasonal migration patterns, many gaps remain, and researchers rarely know the location of the majority of whales at any one time. Biologists have pieced together information on the former distribution of right whales from detailed commercial whaling records and from whales bones excavated from 16th century Basque whaling stations in Labrador. Some of the most fertile whaling grounds in the northwest Atlantic included the waters around Newfoundland and Labrador, Massachusetts Bay, Long Island, and the southeast coast of the United States. But as populations plummeted, so did reports of their whereabouts. Today, researchers know of only five locations where northern right whales gather consistently. These areas include the Georgia and Florida coasts, Stellwagen Bank and Cape Cod Bay, the Great South Channel east of Cape Cod, the Bay of Fundy, and the Scotian Shelf. Right whales have sporadically been spotted near Newfoundland, Greenland, and Iceland. Since 1980, a team of scientists from a consortium of research centers have surveyed the northern right whale population to determine how the whales use their habitats and whether other critical areas exist. To track the whales, researchers had to first learn how to identify and recognize individuals. Such information helps scientists determine whether individual whales return to the same areas every year, which females have given birth, how whales are related to each other, and which ones may have died. Fortunately, right whales are easy to tell apart. All whales have unique patterns of thickened skin patches, called callosities, on their heads. Many whales also have distinctive scars from encounters with boats. Since 1980, researchers have traveled out to some of the major habitats to photograph the whales. Then they compare the pictures to a comprehensive catalog of right whale photographs housed at the New England Aquarium. The catalog contains photos dating back to 1935, but most of the records were gathered since 1979. Few previously unidentified adult whales have been photographed in recent years, leading researchers to conclude that they have records of most of the whales in the population. Scientists also have collected tissue samples from the whales to determine both the gender and the lineage of individuals. Darts, fired from a cross bow, penetrate four millimeters into the whale, extracting a small cylinder of skin and blubber. Although this procedure appears painful, scientists have concluded based on repeated observations that the darts neither hurt the whales nor changed their behavior. The skin samples have provided scientists with valuable insights into the struchture of the population. For example, studies of the mitochondrial DNA from 150 animals have led scientists to conclude that there is just one breeding population and that all the whales are descended from only three females. Such low genetic diversity could help account for the slow population growth. Researchers eventually hope to run more genetic tests and determine the paternity of the whales as well. Scientists have performed toxicological studies of the blubber and found that the whales have been bioaccumulating chemical pollutants such as PCPs and DDT. The effects of these chemicals on the whales' health and fecundity is unknown. By logging the location of individuals over the course of a year, scientists have outlined a general migration route. During the winter, pregnant females travel to the warm waters off the Georgia and Florida coasts-the only known calving ground for the northern right whale-to give birth. This area is so broad that despite extensive aerial surveys, researchers often miss newborns. One of the biggest mysteries, however, is where the males and nonpregnant females go during the winter. At this point, nobody knows. Starting in late February, males and females without calves enter the plankton-rich waters in Cape Cod Bay and over the southern third of Stellwagen Bank. Typically, researchers spot between 30 and 40 right whales around Stellwagen Bank each year. Mothers, accompanied by their newborn calves begin their northern migration in early spring. A few usually arrive in Cape Cod Bay in early April, although the numbers vary from year to year. For example, in the spring of 1995, researchers spotted a record number of right whales in the region, but no mother/calf pairs. Researchers don't know where they went. By May, the whales leave Stellwagen Bank and swim out to feed on the dense copepod patches along the Great South Channel southeast of Cape Cod where they are joined by the majority of the right whale population before heading north. In summer and early fall, approximately two thirds of the mother-calf pairs move into the Bay of Fundy to nurse. Many other whales, both male and female, migrate to the Scotian shelf where they feed and engage in courtship behavior. Approximately half of all known females and three-quarters of all known males have been spotted at least once in this region during the 15 years that researchers have studied the whales. Researchers also suspect that there is a second summer nursing ground. Whereas two thirds of all mothers always bring their calves to the Bay of Fundy, many mothers never show up, and researchers don't know where they go. Scientists have determined, based on DNA studies, that females that had been nursed in the Bay of Fundy usually return after their first year and eventually bring their own calves. Females who were not nursed in the Bay of Fundy rarely appear there. Males, on the other hand, only occasionally return to their nursing grounds. But in recent years, for reasons researchers don't understand, a number of males have shifted their summer grounds from the Scotian shelf to the Bay of Fundy. But right whale appearances are never predictable. In 1986, 23 right whales, including 8 mother-calf pairs, spent the entire summer in the Stellwagen Bank area. Scientists also are discovering that right whales can travel great distances during a short period of time. During one six week period, scientists tracked a female and her seven-month calf from the Bay of Fundy to the New Jersey coast, and back to the Bay of Fundy. Another whale, a juvenile male, was found some 160 km (100 miles) up the Delaware River in December 1993 (he eventually found his way out to sea, but not without at least one collision with a boat). Many researchers speculate that northern right whales' habitat shifts correspond with variations in the availability of prey. These whales have a remarkable ability to locate dense patches of copepods, their primary food. Researchers have documented right whales feeding on patches containing 2 million organisms per cubic meter of water. The location of these patches varies from year to year, and the whales move to take advantage of them. One study even suggests that right whales compete for food with planktivorous fish such as sand lance and herring. In 1986, the summer when many right whales stayed around Stellwagen Bank, there were very few of these fish in the area. In the future, scientists are planning to implant selected whales with satellite transmitters. The transmitter, which is shot from a crossbow, lodges underneath the whale's skin. Several times a day, the transmitter sends a signal to a satellite. Researchers can then download information on the location of the whale. Biologists hope to use this information to locate where males go during the winter and the location of the suspected second summer nursing area. However, the short battery life of the transmitters and the overall expense limits the scope of such studies. Once researchers know the location of these critical habitats, such as the wintering areas or possible second nursing grounds, conservationists may be better able to protect the whales. For example, they may be able to establish additional sanctuaries or perhaps regulate shipping traffic. Biologists estimate that collisions with ships and entanglement in fishing gear has caused over one third of right whale deaths between 1980 and 1995. But it is becoming increasingly clear that right whales are not tied to any particular area, so researchers still have a lot to learn.