Sharks have been portrayed as blood-thirsty monsters, eating humans or whatever gets in their path.However, more people are killed every year by dogs, bees, lightning and lions than by sharks.
As one of the oceans’ top predators, sharks play a very important role in marine ecosystems. They make sure that certain prey don’t become overly abundant, which keeps the marine food web in balance. In this way, they can also serve as indicators of ocean health: if they are thriving, then more than likely, the marine ecosystems surrounding them are also.
Shark Fins
Photo Credit: Jessica King/Marine Photobank
Sharks are not only predators; they are also preyed upon by humans. Many shark species are under threat from overfishing. Each year 73 million are targeted for their fins to make into shark fin soup. Many more are caught unintentionally as bycatch; they get tangled in fishing nets or gear and then drown.
In fact, sharks now represent the greatest percentage of threatened marine species on the International Union for Conservation of Nature (IUCN) Red List of Threatened species. Of the 307 known shark species, IUCN lists 50 as vulnerable, endangered or critically endangered. Only three species of shark have international protection under the Convention on International Trade of Endangered Species (CITES): the white, whale and basking sharks.
Conservationists and scientists are working toward helping conserve sharks. But because sharks are long-lived, slow-growing animals, taking years to reach sexual maturity and then only give birth to a few offspring, any recovery of shark species would be slow.
Meet Shark Experts:
Marine Conservationist Randall Arauz, president of (Programa Restauración de Tortugas Marinas (PRETOMA), has tackled finning and other shark conservation issues. Read his Ocean Voices interview on SeaWeb’swebsite >> NOAA Research Fisheries Biologist John Carlson specializes in research related to the biology and population ecology of sharks, skates, rays and sawfishes. Carlson is currently helping whale sharks in the Gulf of Mexico.Read >>
Did You Know? 1.Sharks have inhabited our ocean for more than 400 million years. Today, sharks live in almost every marine ecosystem on Earth and some can survive for periods of time in freshwater. 2.Shark teeth are arranged in rows, which slowly move forward from the back of the jaw (a bit like a conveyor belt). As the front rows of teeth wear down or fall out new rows move from behind to replace them. These replacements happen about every two weeks. 3.The skin of sharks is much rougher than that of other fish as it is covered with millions of tiny teeth called dermal denticles. These denticles point backwards and help the shark to swim faster by reducing the water turbulence. 4.A shark skeleton is made entirely of cartilage. 5.Sharks have very good hearing and can sometimes hear prey miles away.
Trash litters our ocean and coasts. From plastic bags and bottles to cigarette butts and fishing nets, marine debris affects everything from the environment to the economy; from fishing and navigation to human health and safety; from the tiniest coral polyps to giant blue whales. Discarded or abandoned fishing equipment and other forms of debris can entangle, maim and cause many wildlife species to drown.
Human-made products are not completely biodegradable. These products will take a long time, possibly hundreds of years, to degrade. Some products such as glass never degrade. To determine how long it will take for debris to degrade depends on several factors such as material type, size, thickness, and environmental conditions, such as the amount of exposure to sunlight or location, whether say on the beach or floating at sea.
While photodegradable plastics (plastics capable of being broken down by light) may break down from its first state (or created state), these plastics never completely degrade, but actually divide into tiny pieces called microplastics. Microplastics are the multi-colored pieces of plastic that can be found in a handful of sand on the beach or in the ocean. Scientists are still investigating the impact of microplastics on our ocean and marine life.
Credit: Tom Crowley/Marine Photobank
Credit: NOAA
Fishermen can contribute to the debris problem when they fail to retrieve fishing gear or improperly dispose of fishingrelated trash. Abandoned fishing line, gear, nets and other litter, whether discarded on land or at sea, can become debris with damaging and deadly effects. Marine debris is a global problem that requires global solutions, but fighting marine pollution begins at home and in the office. There are small steps that you can take, from using reusable items instead of single-use products to cutting back on the amount of trash you produce, which can make a big difference.
1. About 16 million debris items enter the world’s ocean and seas each day. 2. Eighty percent of pollution to the marine environment comes from the land. 3. The “Great Pacific garbage patch” is an area of marine debris concentrated in the North Pacific Ocean. Most of its debris is so fine it cannot be seen on the surface of the water or with the naked eye. 4. At least 267 animal species have been reported to have been entangled in or ingested marine debris.
5. Debris is also a hazard to navigation. In 2005, for example, collisions with floating and submerged objects in the U.S. alone caused 269 boating accidents, resulting in 15 deaths, 116 injuries and $2.9 million in property damage. For More Information:
