August 3, 2006
Shark Week
BY: Nilanga
After a long 51 weeks of waiting…It’s finally shark week on the Discovery channel! If you can’t tune in at 9 ET/PT this week, learn more about these incredible creatures below. You can also send a shark e-card or download a shark screensaver (Windows/Mac). Enjoy!
Sharks are some of the most amazing creatures on the planet. They are the top predators of the oceans; they are long-lived and slow to reproduce. Their place in the marine food web is essential for a healthy ocean ecosystem. Tragically, these apex predators are in grave trouble due to human activity. Heavy fishing pressure continues to threaten many shark populations. Many sharks are also vulnerable to the brutal practice of shark finning, where fishermen cut off the sharks’ fins and toss the dead or dying bodies back into the water. There are no international limits on shark catch and every year, around 100 to 200 million members of the shark family are killed. Their decreasing numbers are a great cause for concern to the balance of the ecosystem.
Great white shark (Carcharodon carcharias): As the biggest meat-eating sharks, great whites have gained a fearsome reputation because of their many encounters with humans. They average between 12 and 21 feet but have been recorded at around 35 feet. Great whites have torpedo-shaped bodies and pointed snouts; they get their name from the distinct white coloring on their undersides. Mostly found in temperate coastal waters, great whites have been known to swim down to depths of 700 meters and to travel great distances – up to 3800 km. They prefer coastal waters because that is where preferred prey – seals and sea lions – spend their time. Because of severe overfishing, great whites have been listed as “vulnerable” in the International Union for the Conservation of Nature’s “Red List” of threatened species. Although they are protected in some regions, they lack adequate international protection and continue to be targeted for their teeth and jaws, which are sold on the black market.
Oceanic whitetip shark (Carcharhinus longimanus): Oceanic whitetips are an extremely dangerous species of shark since they are known to be fearless around potential prey. It is an abundant open ocean shark species found worldwide in waters above 200 meters. They are often the first to appear at mid-ocean air or sea disasters and arrive in great numbers. This shark’s large rounded dorsal fin and very long pectoral fins distinguish it from other sharks. The tips of all these fins are whitish in color – markings that give the whitetip its name. Because oceanic whitetips are found all over the world, they are subject to pressure from many fisheries; they are often caught as bycatch along with tuna and other commercially-sought open ocean fish species.
Whale shark (Rhincodon typus): The whale shark is the world’s largest fish. It swims through the water with its mouths wide open, filtering small plant and animal organisms it feeds on. Whale shark distribution spans tropical and subtropical waters where they swim from the surface to a depth of 200 meters. Reaching a length of about 50 feet, they are dark in color with distinct white spots dotting their bodies. Whale sharks are harmless to humans but are very curious about any humans that may want to swim alongside them. Although whale sharks are protected in some parts of the world, fishing still occurs. A majority of these sharks are caught before they reach maturity at or over 20 years of age. Because of overfishing and their demand as a delicacy in countries like China, Chinese Taipei and much of Southeast Asia, they are considered to be a vulnerable species. Unfortunately, their fins also have a very high value in Asian markets. Trade in whale sharks in now regulated by the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES).
Shortfin mako shark (Isurus oxyrinchus): Possibly the fastest shark in the world, the mako has been known to reach speeds between 22 and 60 miles per hour. Makos propel themselves through the water with quick strokes of their tails and make several leaps out of the water when captured. Worldwide in distribution both in tropical and temperate waters, they are mostly open ocean sharks, although they have been observed in inshore areas. These sharks have slender, streamlined bodies made for speed and conical snouts with whitish undersides. A popular target of commercial fishermen around the world, makos are feeling the pressure. They also end up as bycatch in driftnet fisheries.
