Finback Whales (Balaenoptera physalus)

Fin whales on the Ledge: Fin whales have been seen on Jeffreys Ledge throughout the year, but seem to be most common in the summer and fall. They are generally feeding on herring, although at times they also seem to feed on krill, sand lance, squid, and other schooling fish. While generally solitary, researchers at the Whale Center of New England have seen groups of up to ten animals travelling together. For fin whales in the Gulf of Maine, Jeffreys Ledge seems to represent a southern boundary for a portion of the population. Fin whales which are commonly seen in Maine and Nova Scotia waters are sighted with some frequency on the Ledge; however, whales which are often seen on Stellwagen Bank, less than twenty miles to the south, are rarely sighted there. Fin whales are most often seen in the deep waters just west of the Ledge itself, but have been seen in shallower waters many times. Size: 45-70 feet (the second largest of the great whales; blue whales are the largest) Weight: approximately 40 tons as full grown adults Distinctive Characteristics: An asymmetrical lower jaw which is white on the right side and the grey-black of the rest of the whale on the left (baleen also reflects this asymmetry); long thin body with a tall, erect dorsal fin; 50-200 pleats on the lower jaw which expand during feeding. Diet: A wide variety of small fish, with some krill (shrimp-like animals; their primary diet in the southern hemisphere). It is unknown whether this species fasts through the winter months. Distribution: Finback whales are distributed worldwide, with three major distinct populations: the North Atlantic, North Pacific, and southern oceans. While there is certainly some structure to the stocks within each ocean, it remains to be determined what that structure is. Recent photo-identification work indicates that fin whales in the North Atlantic have been detected to move throughout the New England/Nova Scotia region but have never been resighted off of Newfoundland or the Gulf of St. Lawrence. Similarly, genetic work indicates that fin whales in the Mediterranean, on the other side of the North Atlantic, are a separate population. No wintering concentration area is known anywhere in the world; the speculation is that these animals go to deep waters and disperse. There is a possible year-round resident group in the Sea of Cortez in Mexico. Life History: Fin whales are born during the winter at 15-18 feet and approximately 3,000 pounds after a 12 month gestation. Although no one knows where the calving grounds of fin whales are located, the approximate size of calves seen during spring and summer reflect an apparent winter birth season. The calf stays with its mother for 6-8 months, but can often wander up to several miles from the mother even well before weaning. Maturity is believed to take place at 6-8 years of age, and females produce a single calf every 2-5 years. There is some evidence that fin whales may have extremely long lives and may live up to 100 years, although confirmation of this depends on more accurate aging techniques. Social Organization: Fin whales are primarily seen as solitary animals, although coordinated groups of up to 15 animals together have been observed. There appears to be considerable variation in grouping frequency by region; in the New England region groups are uncommon, while they appear to be observed much more regularly off the Newfoundland and Gulf of St. Lawrence coasts. There is some evidence that suggests the groups which are seen may have some stability, but this needs further study. Because of the loud, low frequency sounds made by fin whales, animals may remain in vocal contact over long distances, making it difficult to know when whales are or are not associated. Mating is thought to take place during the winter, although several observations of apparent mating activity have taken place during late summer off the Maine coast. Population Status: Fin whales were killed extensively once "modern" whalers had virtually extinguished blue whales. Between the 1930's and the 1960's over 500,000 fin whales were killed worldwide, mostly in the Antarctic. Although whaling for fin whales took place as recently as 1989, kills were highly limited after 1970. Now protected worldwide, fin whales are estimated to number 60,000 - 100,000 worldwide, and are listed on the Endangered Species list. Currently, the largest threats to fin whales is development and habitat destruction, entanglement, and the interest in several countries for resumed whaling on fin whales. Other Sites: Link #1    Link #2    Link #3