Thursday, January 24, 2008

Shortfin Mako Shark


The shortfin mako shark is a sleek spindle shaped shark with a long conical snout. This shark has short pectoral fins and a crescent shaped caudal (tail) fin. There is a distinct caudal keel on the caudal base. Its second dorsal fin is much smaller than the first. The teeth are are slender and slightly curved with no lateral cusps, and are visible even when the mouth is closed. There is marked countershading on this shark: dorsally it is a metallic indigo blue while ventrally it is white.
The shortfin mako can grow to lengths of 3.9 meters (13 feet). There is still some uncertainty about its life-span, but it is suspected to reach ages of between 11-23 years.
As one of the fastest sharks in the ocean, this powerful shark can attain burst swimming speeds of up to 35 km/h (22 mph) and can leap clear of the water to heights of up to 6 meters (20 feet). These qualities have made this species a sought after sport fish in some parts of its range.
The shortfin mako feeds mainly upon bony fishes including mackerels, tunas, bonitos and swordfish, but may also eat other sharks, porpoises and sea turtles.
Reproduction
Female shortfin makos usually become sexually mature at a length of 3 meters. Developing embryos feed on unfertilized eggs in the uterus during the gestation period of 15-18 months. The 4-18 surviving young are born live in the late winter and early spring at a length of about 70 cm, but have no placental connection during development (ovoviviparity). It is believed that females may rest for 18 months after birth before the next batch of eggs are fertilized.
Habitat
Shortfin mako sharks live in tropical and temperate offshore waters. They are a pelagic species that occur from the surface down to depths of 150 meters (490 feet). This shark is seldom found in waters colder than 16 degrees Celsius.
Range
The shortfin mako is found worldwide. In the western Atlantic it can be found from Argentina and the Gulf of Mexico to Browns Bank off of Nova Scotia. In Canadian waters these sharks are not abundant as they prefer warm waters, but neither are they rare. Shortfin makos are often found in the same waters as swordfish as they are a source of food and both fish prefer similar environmental conditions.