Factors Affecting Marine Dolphin Population - Report Example

Marine Dolphins Introduction Dolphins are known as small cetaceans, though some dolphins are quite large. They can mature upto a length of over 20 feet. The biological classification of dolphins is as follows: Kingdom Animalia Phylum Chordata Class Mammalia Order Cetacea Sub-order Odontoceti Family Delphinidae Genus Delphinus Species delphis From the classification, the scientific name for dolphin is Delphinus delphis. Dolphins have their habitats in oceans, seas and major rivers. They have become specialized to their different ecological niche that they occupy. Dolphins are exclusively carnivorous. Some feed exclusively on fish or cephalopods. Cephalopod is a class of marine that includes cuttlefish and octopus. Other dolphins have a varied diet that may include lobsters, crabs, squid, shrimps and fish. The dolphins bear live young ones and feed the young ones with milk. Many marine dolphins are facing extinction due to human activities, but some laws have been formulated to protect their existence (Nakamura 64). Types of Marine Dolphins The major types of marine dolphins are pacific bottlenose, rough-toothed, spotted dolphin and spinner dolphin. The bottlenose dolphins are the most famous of all cetacean species. The scientific name for bottlenose dolphin is Tursiops truncatus. Rough-toothed dolphin has vertical grooves that run from the gum line to the tip. The scientific name for rough-toothed dolphin is Steno bredanensis. Spotted dolphins are of smaller size than rough-toothed or bottlenose dolphins. They have a dark cape that extends from their forehead to the dorsal fin. The scientific name for spotted dolphin is Stenella attenuata. Spinner dolphins are smaller than the spotted dolphins. The spinner dolphins got their name from their spinning behavior. Their scientific name is Stenella longirostris (Shirihai 77). Adaptations of Marine Dolphins Like other marine animals, dolphins have become adapted to the sea life. Anatomically, the bodies of the dolphins are streamlined to enable them to move more efficiently in the aquatic environment. The streamlined body ensures fast movement of the dolphins as it reduces the resistance of water when the dolphin is moving. The hind limbs of the dolphins have disappeared, and front limbs are developed into flippers (Gordon 26). This helps the dolphin in steering balance and changing direction. The dolphins have a powerful tail, which helps in propulsion. The speed under which the dolphins move at is closely related to the feeding habit of the dolphin. Research has shown that those dolphins that feed on slow moving prey do not exceed a speed of 10 mph. Other dolphins that feed on fast moving fish species usually attain a speed of up to 15 mph. In addition, dolphins have a smooth skin. The dolphin’s skin is thick, hairless and lacks glands. It is kept smooth by the constant slough and replacements. For example, the bottlenose dolphin replaces its outermost skin layer after every two hours. This smooth skin of the dolphin increases the speed at which the dolphin moves. Like other marine mammals, the dolphins have a thick layer of blubber below their skin. This layer of blubber is important since it insulates the dolphins against heat loss. The dolphins rely on their sense of hearing to detect any danger around them. The sense of hearing in dolphin is a very complicated behavior referred to as echolocation. Echolocation is where, a dolphin emits a series of split clicks by its blowhole focusing the sound to the melon and the melon directs the sound pulses in a directional beam. When the directed sound waves hit an object on its path, it is reflected back to the dolphin, and the dolphin detects an obstruction ahead on its way. Through echolocation, a dolphin is capable of detecting the distance, size, shape and direction of movement of objects in water (Smolker 54). Factors Affecting Marine Dolphin Population Tuna and Dolphin Issue Dolphins and Tuna often swim together. The tuna tries to take advantage of food finding tactics of dolphins. Anglers have discovered the relationship between dolphins and the tuna. The use of purse-seining fishing technique has seen to the reduction of the number of marine dolphins. Traditional methods of fishing could not catch dolphins when they were spotted together with the tuna, but with the introduction of purse-seining technique, high speed boats are used to catch the dolphins, thus reducing their number. Mostly, the species affected by purse-seining technique is the spinner and spotted dolphins. Purse seining has been believed to reduce the number of spinner and spotted species drastically. Driftnets and gillnets technologies have also led to killing of many dolphins every year, which have led to the reduction of their number. Hunting for Subsistence Use Man has hunted dolphins for subsistence food. The dolphins have also been hunted for fertilizer, oil and other products. For instance, Turkey has intensified hunting of dolphins in the Black Sea in order to produce chicken feed and oil. Subsistence hunting still takes place in Solomon Islands, Artic parts of United States and Canada and in Greenland. This hunting of dolphins for oil, food and other uses has reduced the number of dolphins tremendously. Habitat Degradation Contamination of the marine ecosystem poses the greatest danger to the reduction of dolphin’s number. Pollutants such as heavy metals, pesticides, radioisotopes, PCBs, plastic particles and other industrial wastes do not decompose or take a very long time to decompose, thus polluting the marine environment. Through biomagnifications, the toxins are absorbed and accumulated in organisms in the lower trophic level of the marine. When dolphins feed on the organisms in the lower trophic level, the dolphins take and accumulate the toxins in large quantities, which lower the reproductive life of the dolphin and weaken the immune system making the dolphins susceptible to diseases. This pollution reduces the number of marine dolphins. Protective Measures Marine Mammal Protection Act (MMPA) is one of the protective measures that have been endorsed in order to protect the dolphins. In U.S, MMPA prohibits harming, hunting or harassing any marine mammal. This Act protects the dolphins from human activity such as hunting. IDCA of 1992 is another Act that protects the dolphins. The endorsement of IDCA has seen the eradication of purse-seine nets. Countries performing purse seining on dolphins are provided with incentives to stop purse seining. IDCA is vital to the conservation of marine dolphins. Conclusion Despite, the laws that are in, existence to govern the protection of marine mammals, dolphins included, there has been an increasing, human activity that is diminishing the number of marine dolphins. Although, not all marine dolphins are endangered, policies to regulate their population should be formulated in order to protect even the dolphin species that are not endangered. There are two most common marine species of dolphin, which are endangered; these species are the Indo-pacific and the pink dolphin. These two belong to the bottlenose species. Recommendations The governments should consider educating the mass on the need to preserve the marine dolphins. It is very difficult for an individual to kill or destroy what he has come to love. If people are educated on the marine dolphins and their importance, this would be the first step towards making people preserve what they are aware of; hence, the education would make people preserve the marine dolphins rather than killing them. Governments should come up with laws to curb illegal trading of dolphin made products. Many governments have not come up with laws that prohibit the sale of products that use dolphin to see to their manufacture. Absence of laws to govern this illegal sale has made the illegal trade flourish, thus encouraging the destruction of the marine habitats of the dolphins by human activity such as hunting. Governments would reduce hunting of dolphins by putting up laws to restrict the illegal trade. This will lead to protection of the endangered marine species. Putting up of laws to govern directing industrial wastes to marine water may save the life of the marine dolphins. Many industrial wastes that are directed to seas and oceans are the major causes of the decreasing number of marine dolphins by causing deaths to the dolphins. However, if proper industrial laws were put in place to restrict directing industrial waste to seas and oceans, a great number of marine dolphins would be saved. Penalties for realizing industrial wastes to the marine environment should be formulated in order to make the industries follow the set laws. Work Cited Gordon, David. Uncover a Dolphin. Boston: Silver Dolphin Books, 2008. Print. Hoyt, Erich. Marine Protected Areas for Whales, Dolphins and Porpoises: A World Handbook for Cetacean Habitat Conservation and Planning. Denver: Routledge, 2011. Print. Nakamura, Tsuneo. Dolphins. New York: Chronicle Books, 1997. Print. Reiss, Diana. The Dolphin in the Mirror: Exploring Dolphin minds and Saving Dolphin Lives. Denver: Houghton Mifflin Harcourt, 2011. Print. Shirihai, Jarrett Brett. Whales, Dolphins, and Other Marine Mammals of the World. New York: Prentice Hall, 2006. Print. Smolker, Rachel. To Touch a Wild Dolphin: A Journey of Discovery with the Seas Most Intelligent Creatures. Denver: Anchor, 2002. Print. Read More