Studying Individual Whales
Prior to the 1970s, knowledge about whales was gained primarily through the study of animals that were tagged or taken by whalers.
Since the 1970s, photo identification has become a primary method for studying whales. By photographing unique physical characteristics of the whale, such as dorsal fin shape and body coloration patterns, researchers are able to tell many individuals apart within a population of a particular species.
How to Tell Whales Apart
Each whale species has a set of distinctive features, which scientists use to identify individuals. One whale species that is fairly easy to distinguish is the humpback whale. Every humpback has a unique pattern on the underside of its tail, which is just like our fingerprint. The pattern ranges from all black to all white. A humpback whale will often lift its tail, or fluke, up when it dives, allowing a researcher to photograph this pattern.
Some whales do not life their tails up when they dive, or do not have a pattern on the underside of their tails. In this case, researchers have other methods to tell them apart. These may include distinguishing the whales by the shape of their dorsal fin, pigmentation patterns on their bodies, or by unique scars or markings on the whale.
What Can Photo-Identification Tell Us?
Once a sighting record is established for an individual whale, researchers are able to study their movements, migration, feeding patterns and life history (including age of maturity, calving interval and life span). Population estimates may also be obtained by tallying known individuals. Preferred feeding grounds can be noted as well, making it possible to identify locations as prime feeding areas and areas that may need protection.
Names for Whales
Researchers in New England and other areas often see the same individuals year after year and many of the whales have been given names. The names usually relate to a marking on the whale so that the researchers will have an easier time remembering the name when they see the whale out on the water.
Using photo-identification, over 2,400 humpback whales have been cataloged in the Gulf of Maine. Many have "family trees" showing their lineages. One of the first whales identified in the Gulf of Maine was "Salt," a female whose dorsal fin is speckled white. Salt was first photographed in 1976 and has been seen nearly every year since. In 2008, she returned to the Gulf of Maine with her eleventh calf. Salt's family tree is extensive, and information such as this allows researchers to learn much about the life history of whales, such as calving intervals, if calves return to the same feeding and breeding grounds as their mothers, and how often they associate with their relatives.
