Porbeagle Shark

The Porbeagle Shark (Lamna nasus) is a common, fast-swimming, potentially dangerous shark. They are dark gray on top and white underneath; there is also a small patch of white on the rear edge of the dorsal fin. Porbeagles have a torpedo-shaped body and a crescent shaped tail with a secondary keel that effectively cuts the water during the side to side swimming motion. This makes them very efficient swimmers. Adults can attain a size of 12 feet (3.7 meters) weighing about 350-550 pounds (160-250 kg) and have an average life expectancy of 30 to 40 years. This shark has relatively large eyes. The teeth in the moderately sized mouth are similar in both the upper and lower jaw (they are smooth-edged with lateral denticles), although young individuals may lack the lateral denticles.

The porbeagle has a heat regulating mechanism that raises the body temperature 36.9 to 47 degrees F. (2.7 to 8.3 C.) above the surrounding water temperature. This allows the shark to operate more efficiently in the cooler waters it inhabits. Unlike many other sharks the porbeagle must swim at all times in order to breathe.

Porbeagles occur on both sides of the Atlantic, and in the south Pacific and Indian Oceans. In the western North Atlantic it can be found from Raleigh, Newfoundland at its northernmost range to the Gulf of St. Lawrence, the Scotian Shelf, the Bay of Fundy and the Gulf of Maine to New Jersey and perhaps to South Carolina. Off Nova Scotia the porbeagle is generally found in waters less than 57 degrees F. (14 C.).

There is apparently little exchange between porbeagle populations. For example, populations of the northwest Atlantic seem relatively segregated from those of the northeast, and populations in the northern hemisphere are separate from those in the southern hemisphere .

The porbeagle shark inhabits water down to a depth of 1,120 feet (370 meters). It is most commonly found on continental shelves or inshore. It prefers cool waters and is usually found in temperatures below 57 degrees F. (14 C.).