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Back to Subjects - Animal Science & Zoology

Shark Conservation

Shark Conservation Arising over 350 million years ago, the shark species has been labeled as a human devourer. Now, with the increase in human population, the demand for shark meat, fins, and cartilage are at an all time high; therefore, the existence of the shark is becoming a concern (Budker 1971). Individuals are conditioned to think of sharks as a negative aspect to the environment, which is prolonging the effort to save shark species from becoming extinct. With that in mind, some private as well as national organizations have accepted the challenge of educating and informing people about the existence of the shark specie and its importance to the sea. Portrayed as the beast of the sea, the shark species is a cold blooded animal that shows great diversity in size. The largest of the sharks measure up to 13.7 m, while the smallest of the species range from 22-to-25 cm (Ellis 1976). Typically, these creatures of the sea have a fusiform body, that is composed of cartilage, which is capable of reducing drag and the amount of energy needed to swim (Ellis 1976). Their countershade coloration allows the species to blend in with both the dark depths and the light surfaces of the sea (Ellis 1976). These beautiful dwellers of the sea also possess rigid fins that are supported by cartilaginous rods. All together the shark has five different types of fins: the paired pectoral fins, are used to lift the shark as it swims, the paired pelvic fins stabilize the shark, the one or two dorsal fins also stabilize the shark, a single anal fin provides stability in species where it is present, however not all sharks have the anal fin, and the caudal fin which propels the shark (Lineaweaver and Backus 1970). The sharks head structure consist of lateral eyes, a ventral external nose, and a mouth that is ventrally located at the tip of the snout. Some species possess an eyelid like structure called a nictitating membrane, which helps in protecting the eye from being injured when prey are thrashing around, and a nasal barber, which are sensory projections near the nasal (Lineaweaver and Backus 1970). In the mouth, teeth are modified, enlarged placoid scales. Having numerous rows of teeth attached at their bases by connective tissue, sharks have rows of replacement teeth that are continually developed behind the outer row. As the functional teeth fall out, the replacement teeth will take their place, and in some species as many as 30,000 teeth are replaced within a lifetime (Lineaweaver & Backus 1970). Shark mating rituals vary from the size of the shark and its specie. In smaller, more flexible species, the male coils around the female, while the male of the larger specie orients himself parallel and head-to-head with the female (Woums & Demski 1993). Some species mating rituals also consists of males biting females on the pectoral fins or the middle of the back to hold on to them (Woums & Demski 1993). The female will often bear scars or marks, after the ordeal. Due to the fact that sharks are cold blooded animals, there is no precise gestation time. The development of the embryo will depend solely on the temperature of the water, however, the gestation period can last anywhere from 2 months to 2 years (Woums & Demski 1993). Within shark species there are two methods of reproduction. In some cases a female shark will lay eggs in a coastal nursery where the presence of other sharks are absent. And in other cases, usually in the larger sharks, females give birth to live offspring (Wourms & Demski 1993). In which case the young are born fully developed, and once they are born they shoot away fast or they risk being eaten. Adapted for a wide range of aquatic habitats, various shark species inhabit shallow coastal habitats, deep-water ocean floor habitats, and the open ocean. With a wide selection to feed off of, as a whole the shark species feed on just about everything. Their diet consists of fish, crustaceans, molluscs, marine mammals, and other sharks. When preying for their daily bread, the shark will seek out the weak, ill, injured or dying prey because it is easier to catch. Socially, sharks have been identified as anti-social, however, many species demonstrate various degrees of social behavior. The shark species also demonstrated that their greatest activity occurs during the twilight and dark hours. Unwilling to support the fight to save sharks specie because of pre- conceived notions, individuals are miseducated about sharks specie and their attacks on humans. There are only 32 species of sharks that have been identified to have attacked humans or boats (Davies 1966) These species have three features in common: they prey on fish or marine mammals, grow to large size, and frequent warmer dwell in waters where swimmers are apt to be. In 1958, the U.S. Office of Naval Research and the American Institute of Biological Sciences indicated that humans become prey by accident. Most shark attacks involve people handling hooked shames or snared divers for prey (Baldridge 1974). Sharks may also attack from a territorial dive, with no intention to feed. An analysis of 1,000 recent shark attacks world-wide showed that well over 50% of the attacks were not feeding related. Up to 60% of shark attack injuries are slashes of the upper jaw teeth (Baldridge 1988). This behavior is typical of courtship advances by some male sharks. Sharks may also injure victims by bumping them vigorously, but most sharks move in cautiously when attacking. However, the best way to reduce the chance of an attack by a shark is for swimmers and divers to stay clear of seal and sea lion rookeries, or other known areas frequented by sharks. As the world's population continues to grow, the sea is being purged of the shark specie, because of the increased demand for shark flesh, fins and cartilage. Because the demand for various parts of the shark are becoming so high, they are being directly targeted in various commercial and recreational fisheries throughout the world. Not only are sharks in danger of being targeted by commercial and recreation fisheries, but sharks are all too often captured incidentally with tuna and billfish fisheries. As much as 50% of the reported take of commercial shark fisheries are shark by catch in large scale high seas fisheries (Martin 1985). The number of sharks caught between 1989 and 1991 by various high seas fisheries estimated at 11.6 to 12.7 million (Allen 1999). Most of these by catches were from long line fisheries for tuna of Japan, Korea, and Taiwan. According to the National Oceanic Atmospheric Administration (NOAA), between the early 1970's and late 1980's the abundance of many shark species found along the southeast coast of the U.S. had declined as much as 80% (Martin 1985). Playing a crucial role in their ecosystem, sharks are highly efficient predators that keep ecosystem populations in check by hunting and killing other animals, particularly those that are weak or diseased (Perrine 1999). Therefore, without sharks the population of other animals will increase to unsustainable levels. Despite the fact, that these creatures are needed to maintain the health of the ocean ecosystem, they remain a hot commodity for both commercial and recreational fisherman since the 1980's with millions of pounds hauled in annually for restaurants as well as trophy cases (Perrine 1999). The carcasses of the sharks are prized for their fins, teeth and various parts that are used as a lubricant or in cosmetics and vitamins. However, the amount of sharks being caught has declined by up to 50 percent, because it has become apparent that sharks have become overfished in the last 20 years (Perrine 1999). In an effort to save sharks, the United Nations rendered oversized drift gill-nets illegal, however there is inadequate enforcement and a lack of overall judicial fortitude regarding high seas poaching and overharvesting (Martin 1985). Independently, some nations have taken steps in an effort to bring forth a change, but these efforts are often last resorts applied to a shark fishery that has already crashed. The South African White Shark Research Institute is a non-profit organization that is dedicated to the research of the world's greatest predator, and the preservation of its environment (Martin 1985). The WSRI has put forth a strong commitment to educating at all levels, which has led the group to establish one of the world's largest and most far reaching educational and conservation programs on sharks (Martin 1985). To accomplish the goal they have set before themselves, the institutes objectives are to change negative public attitudes towards sharks. With a number of various programs the WSRI has used different avenues to inform the world about the beauty of the shark. They have the international membership adoption program, in which four newsletters are published a year. Then there is the unique schools educational program in which school pupils are invited to join the research team on field trips to come face to face with Great White Sharks. There is the national and international lecture program that consists of lectures given at schools, dive and fishing clubs, universities, public talks and campaigns. The WSRI also has the trade fares and expos program. This program allows the group to display educational information at as many trade fares and expos as possible. Working against trophy fishing, the Management Councils have imposed a limit on the total amount of large, coastal sharks that can be caught by commercial fishermen in the Atlantic, Caribbean, and Gulf of Mexico. This annual quota has been scaled back periodically because of continued concerns that sharks are overfished. To insure that the quota is not exceeded, the year is divided into two six-month long shark fishing seasons. The first season ends when one-half of the total allowed catch is reached. The second season begins July 1 and the quota for the season is adjusted based on any excess catches during the first season (Perrine 1999). Supporting the Management Councils the National Marine Fishery Service (NMFS) imposed the first quota on the commercial catch of small coastal sharks and prohibited direct fishing for five species of sharks that were determined to be especially threatened by overfishing (Perrine 1999). The five species listed by the NMFS are: whale, bigeye sand tiger, sand tiger, basking, white Shark Sharks are especially vulnerable to fishing pressure because of their slow rates of maturation and reproduction turn over. And the prevalent negative attitude towards sharks has produced a nonchalant and emotionless feeling to the slaughter of the shark species. Therefore, with positive education as an antidote to false and negative publicity the battle to save the endangered shark will be possible. In order to win the battle of losing the shark, the support of the general public will be needed to achieve this goal. Bibliography: Work Cited Baldridge, H.D. 1974. Shark Attack. Berkely Pub. Corp., New York. 263 Baldridge, H.D. 1988. Shark aggression against man: beginning of an understanding. 74(4):208-217 Budker, Paul. 1971. Life of Sharks. Columbia University Press. 10-18pp. Davies, D. H. 1966. About Sharks and Shark Attack. New York Hobbs, Dorman. 240-255 pp. Ellis, Richard. 1976. The book of Sharks. New York Grasset and Dunlap. 110-130 pp. Lineaweaver, T. H., and R. H. Backus. 1970. Natural History of Sharks. Philadelphia and New York. 23-40 pp. Martin, M. 1985. The shark: more threatened than threatening. Sea Frontiers. 31: 296-303. Perrine, D. 1999. Sharks and Rays of the World. Voyageur Press, Stillwater, Minnesota. 132 pp. Woums, J., and L. Demski. 1993. Reproduction and Development of Sharks, Skates, Rays and Ratfishes. Environmental Biology of Fishes. 38(1): 270.

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