Basking Shark (Cetorhinus maximus)

Basking sharks on the Ledge: Basking sharks are seen most often on the Ledge in late summer. They are plankton feeders exclusively, and significant numbers of them can show up suddenly when plankton patches exist (groups of up to 30 within a mile have been reported in the past several years). When food is abundant, they can sometimes stay on the Ledge for several months at a time; in 1995, researchers saw one shark with a distinctive dorsal fin from late July through early October! While they are normally slow, placid swimmers, they have been reported to jump clear of the water, although no one knows why they do this. Size: The second largest fish in the world, basking sharks can reach lengths of up to 45 feet, although most are 12-25 feet long. The longest measured in the western North Atlantic were 32-35 feet. Weight: A 30 foot basking shark is 6,500-8,000 pounds; "standard" size basking sharks are 1,500 - 6,000 pounds. Distinctive Characteristics: Basking sharks are commonly noted from a distance by their big, floppy triangular dorsal fin; upon closer inspection, the dorsal tip of the tail can also be seen. At close range, they are obvious because of their long gills (which actually can connect on the neck, forming one long gill from side to side), and their wide, circular mouth (which is often opened as the animal swims). Diet: Basking sharks feed only on plankton, especially copepods and small crustaceans. They feed by swimming with their mouth opened, filtering these tiny animals out of the water with "gill rakers" (small filtering devices on the gills themselves). It is analogous to the way skim-feeding whales like right whales acquire their prey. Every so often the sharks then close their gills and "backflush" the prey into their throat, where it is swallowed. Distribution: Basking sharks range throughout the ocean, and are also found in some numbers off the coats of the United Kingdom during the summer. In general, they range as far north as the south coast of Iceland and Greenland, and as far south as North Carolina in the west, and the Mediterranean in the east. Although they are found here mainly during summer, it is thought during the winter they may move offshore, where temperatures stay more constant. Life History: Virtually nothing is known of the reproduction of basking sharks. Offspring are born at 5-7 feet after internal fertilization and development. The slow reproduction of basking sharks makes them very prone to over-fishing, as it would be easy for reproduction to fail to keep up to the level of a fishery take. Population: There is no good estimate for the population of basking sharks. They were hunted in the 1800's for the oil from their liver. The liver can make up 25% of the body weight of a basking shark, and it uses the high oil content to adjust buoyancy. Whalers would harpoon basking sharks and use the oil for the same purposes as whale oil - primarily as lamp oil. They were also able to extract large amounts of Vitamin A out of the oil as well. More recently, basking sharks have been hunted for their meat and their fin, which is a delicacy used in Chinese Shark Fin soup. Other Sites: Link #1    Link #2    Link #3