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Dolphin Auditory-Warning System MAG
When we selected the topic for our project, none of us ever expected to develop a personal attachment to the marine mammals called dolphins. We all anticipated long hours of research and reading. However, before we picked up a telephone or entered a library, we sat down in front of a television to watch a home video of a summer vacation on Puget Sound near the San Juan Islands. The video began with the jostling motions of the cameraman as he leaned over the front railing of the boat. The picture shifted from the left side of the boat to the right just in time to see a black and white shape roll and reverse its direction. Then from the left hand side of the screen a similar shape breached the surface of the water, took a breath, and then submerged again. The Dall's porpoises frolicked in the bow wake of the boat for another fifteen minutes, enjoying themselves thoroughly. Their beauty and grace was overwhelming. Those of us watching the video were forced to pause for a few seconds in sheer admiration of the animals. It was then that our project earned our emotional commitment.
The Plight of the Dolphin
The personal encounter with one species of dolphin - even on a shaky home video - made the review of literature and dolphin studies all the more interesting and eventually all the more painful. Reports of atrocity after atrocity being committed against these gentle sea mammals produces a passionate desire to come to their aid. Dolphins live in a threatened world today, for they are being killed by man in great numbers. The carcasses of 6,000 striped dolphins are found monthly in the relatively small area around the Mediterranean Sea. In 1987 and 1988, half of the bottlenose dolphin population of the United States' mid-Atlantic coast died. Before the U.S. government and tuna companies began taking regulatory steps to control fish-netting, over a half-million dolphins died annually. Today the number has decreased to about 80,000 a year, but it still remains an unacceptable figure.
There are several causes of these dolphin deaths. Pollution is one significant cause of death. The greatest threat to the dolphins, however, comes from drift netting and tuna netting. Netting is directly responsible for about four-fifths of all unnatural dolphin deaths. This problem of netting is the focus of our research. We hope that, by amending the drift netting and tuna netting processes, the lives of thousands of dolphins can be saved annually.
Drift netting utilizes nets that are constructed of virtually indestructible nylon mesh which extend forty miles wide and thirty feet deep on average. The nets are released in early evening and left to float throughout the night. During these hours, the nets entrap enormous amounts of marine life, dolphins being a great part of the animals trapped unintentionally. Environmentalists have called this "strip mining" the ocean. Every night, 20,000 miles of this type of net are released, and only 9,000 are collected each morning. Last year alone, 4,015,000 miles of net, enough to wrap around the earth more than 160 times, were allowed to continue wandering the open oceans killing everything that came within their reach. These "ghost fishnets" float along the surface until they are laden with dead animals, whereupon they sink to the ocean floor. On the ocean floor, the organic matter eventually decomposes, and the nets return to the surface. Once at the surface. the cycle of death begins again.
Dolphin deaths occur in even greater numbers as a result of the second fishing method, called drag netting. This increase in dolphin deaths, in the eastern and tropical Pacific, is due to fishermen's targeting schools of dolphins because they are evidence of nearby tuna. In this region, tuna commonly swim with the dolphins, conversely, in the Atlantic Ocean, tuna and dolphins do not share common feeding grounds. Frequently, fishing boats actually ease their nets directly on the dolphins in order to catch the tuna feeding beneath them. Tuna boats are now required to open a "trap door" in the back of their nets to release non-commercial sea animals that might have been "inadvertently" caught. The fact is, that long before the trap door is opened, the dolphins which are caught have drowned, being dragged for miles behind the trawler in positions that do not enable them to reach the surface to breathe.
The fishing industry's use of Pacific dolphins as a type of buoy for tuna is a horrendous crime. Fortunately, mainly through media exposure, the world has been alerted to the situation. In response to ever-growing pressure from the public, Starkist Tuna Company adjusted its netting practices and put dolphin-safe labels on its tuna cans. Other companies soon followed their lead. This hardly abates the danger to dolphins from tuna fishing. There has been little improvement because the only requirement for the "dolphin-safe" label is the execution of the "trap door" method which is only semieffective. Over 80,000 dolphins are still dying annually as a result of the fishing methods employed in the harvesting of tuna and the secondary catches of salmon and squid. With the astonishing tally of dolphin deaths worldwide it is not hard to see why a solution to this problem is desperately needed.
Present methods employed to try and save the dolphins are sadly ineffective. A new technique is needed; this paper proposes a solution. Nets can be made safer for dolphins by employing the intelligent nature of the dolphin. The communication skills of dolphins can be used to warn them away from tuna nets. In theory, if nets carry some means to warn the dolphins of danger, the animals will alter or reverse their course. To induce such a behavior, waterproof speakers can be lowered with the tuna nets and transmit a signal that will indicate "danger" to the dolphins. Theoretically, this action will remove significant numbers of dolphins from the area of the nets and, thereby, save their lives.
Foundations of Hypothesis
The auditory-warning theory described in this paper is based on three experiments regarding dolphin behavior. The first experiment was a fairly simple study of the dolphin language. Captive dolphins were monitored for extended periods of time, during which recordings were made of their communications in the tank. At the close of the experiment, scientists were able to make several important determinations. Among other things, each dolphin seems to employ a signature whistle to identify itself and convey its emotions. Each individual uses its own distinguishable whistle repeatedly upon meeting a new dolphin or when simply reintroducing itself to previous acquaintances. Dolphins can communicate their emotional state by varying the pitch and duration of their signature whistles. This basic aspect of dolphin communication serves a primary purpose in our hypothesis.
The second study relevant is an intensive investigation of group behavior among dolphins. The study concluded that dolphins are creatures with remarkably human behaviors. A variety of complex relationships is documented. The dolphin social system features lasting friendships, altruism, baby-sitting, cooperative defense and elaborate conversations. Dolphins tend to associate closely with others of similar gender and age. Two male dolphins, the subject of this study, both distinguishable by heavy scars, were seen together constantly from the year 1975 to 1989.
Many studies, like the one just cited, have shown that mothers and their young form very tight bonds, remaining in constant contact until the calves are between the ages of three and six, although some bonds last even longer. Dolphin mothers are also very cooperative. A group of them will form a "playpen" around their calves so that the young can interact in a protective environment, similar to a child's play group. Baby-sitting and aunting, in which one female looks after another calf, are also common. There are many reports of dolphins rendering assistance to companions in distress, for instance by biting nets to free trapped dolphins, and sharing food from mouth to mouth. All of these features of dolphin "culture" lead to two important conclusions. First, dolphins live in groups that have very strong ties. Much sharing occurs, and one of the things that dolphins readily share is information. Danger perceived by one of the group is perceived by all. Second, a school of dolphins depends on each other and rarely separates. The school moves as a unit, leaving no stragglers.
The third significant experiment was conducted in a dolphin research facility in Scotland. It supports the idea that dolphins, when faced with a potentially dangerous situation, will act tentatively. In this experiment, which took place in the open ocean, dolphins were confronted with what the scientists had dubbed "fake fish." The "fake fish" was merely a long, thin piece of plastic lowered into the ocean, supported by buoys. When the plastic sheet, approximately 100 meters in length, was placed directly in the path of the dolphin school, the dolphin paused in front of it, and then began to bombard it with their sonar. Dolphins sounding an object with sonar remain in place and wait "to read" the return. They appear to process the information that they collect and then react accordingly. In this study, scientists concluded that what the dolphins thought they were facing was the underbelly of a very large fish. The implications are twofold. First, when dolphins are faced with the possibility of danger they choose to avoid it. Second, the dolphins' reaction to the breadth of this particular danger was to swim 100 meters to the side, and then to try to proceed in their desired direction. These behaviors help us to gauge the potential reactions of the dolphin to the net alarms which are the focus of our hypothesis.
Predictable dolphin behavior provides a basis upon which to form a final hypothesis for constructing an auditory net-warning device. Relying on the research of other scientists, it is possible to predict the reactions of the dolphins. It is an established fact that dolphins have a complex communication system. Contained in this system is the ability to announce the presence of danger, usually done with the dolphin's signature whistle. The signature whistle communicates the dolphin's emotional state to other dolphins, as well as its identity. It is possible to duplicate the signature whistle of a very worried dolphin, or a school of worried dolphins. Theoretically, any school of dolphins would be alerted and compelled to flee when subjected to the recorded danger sounds emanating from the area of a fishing net.
Dolphin reaction to potential danger is documented in the two studies previously described. The dolphins, when faced with a potentially dangerous situation, react with general confusion, and appear to communicate among themselves. Group decision appears to weigh against confrontation. The larger the school, the more likely that strong familial ties will prevent the dolphins from entering into a dangerous situation. Communal schooling behavior of dolphins reinforces the idea that dolphin lives can be saved if net-warning devices are deployed. Signals will not need to be broadcast to every member of target schools. Dolphins at the leading edge of a traveling school may be counted upon to relay danger signals to following dolphins.
Hydrophones, powered by battery in the case of the drift net or by the trawler that drags it in the case of the tuna net, would be attached to the nets in strategic locations. They would broadcast an excited dolphin signature whistle: the kind that would say "danger ahead." The recording could be produced by introducing a frightening stimuli into a captive school of dolphins. Dolphins receiving auditory messages will pause in front of the net to evaluate the message. Research indicates that their likely response is to play it safe and take a mild detour around the danger. The motivation to make the decision to avoid danger will be compounded by the size and age of the school, and the need to protect mothers and children. During migration, no dolphins are likely to leave the school, and the school as a whole will clear the net.
Proving the Hypothesis
Data to support a theory regarding the hypothesis is largely conjectural. To actually determine the effectiveness of the auditory-warning hypothesis it must be put through a series of trials. Initially, a standard controlled experiment would need to be performed in order to obtain a recording of warning sound and determine its effectiveness. To conduct such an experiment, the materials would be a recorder, a substantial number of dolphins and a large, enclosed area. Several conditions would also have to be met regarding the experiment: a) the recorder would need to be made as inconspicuous as possible, b) the sea water enclosure or tank should be quite large cross-sectionally as well as deep, c) a sufficient number of dolphins swimming in the pool together would help to simulate schooling behavior. Different kinds of stimuli should be introduced in one area of the dolphin enclosure and the sounds of their reactions to the stimuli should be recorded. A statistically significant number of trials of each stimulus should be conducted before introducing a new stimulus in order to identify differences in dolphin reactions. The recording most effective in producing a fear/flight reaction should be the one which is broadcast from the auditory-warning net speakers. An additional open-ocean experiment to test how far the sound would travel in water, and at what point the dolphins recognize it, will be required.
The true test of the hypothesis is a direct statistical plot of dolphin deaths in tuna nets with the auditory-warning speaker system versus those without. Data to be compiled over a period of a year or less, should involve two separate fleets of trawlers; one equipped with nets that have the speaker system, and one with standard nets. Over the specified period of time each fleet should keep a running tally of the number of dolphin deaths attributed to its nets. If there is a marked decrease in the number of deaths by speaker-augmented nets, then the effectiveness of the auditory-warning speaker system is proven.
There are some potential faults in the hypothesis. One characteristic of dolphins that has been identified is their inherent altruism. This leads one to the question of whether or not the sound of a dolphin in distress would cause other dolphins to swim towards, rather-than away, from the sound. This characteristic would be unpredictable and is not a controllable factor. Research suggests, however, that dolphins will not generally rush to the aid of an unknown dolphin. Family ties are strong within the dolphin school, but probably not strong enough to take unknown amounts of risks for a stranger. There may also be a problem associated with the relationship between dolphins and tuna. Tuna have been known to follow dolphins in the eastern and tropical Pacific and share common feeding grounds. The speaker system in these areas, if effective, may deter tuna from the nets as well as dolphins. However, the tuna do swim at a much greater depth than the dolphins and may not adjust their course in time to avoid the nets even if they are alarmed by the dolphins' reactions to the auditory-warning system. The potential tuna losses from the system in the Pacific are still offset by the potential gains in dolphin safety, for the system can be deployed to any area where dolphins are threatened.
The speaker system need not be solely applied to tuna netting and drag netting. Nets are not the only reason that dolphins are dying today. Pollution is another major factor. If the devices are effective on the nets, there is reason to believe they will achieve similar results when surrounding a temporarily polluted area, or even a waterfront where dolphins have been known to beach themselves.
The speaker system may also provide benefits for corporations and environmentalists. Recently, some tuna companies began to make use of the "dolphin safe" label on their tuna cans. It has resulted in increased sales for those individual companies. As Greenpeace International points out in its report on tuna fishing, "dolphin safe" only means that the "trap door" is opened in purse-seine nets, and only applies to the nets deployed in the Atlantic Ocean; a method which saves an insignificant number of dolphins on an annual basis. If the advertising phrase is "dolphin free," a goal that our hypothesis targets, instead of "dolphin safe," the corporation that is first able to support such a claim will conceivably see returns greater than those accompanying the "dolphin safe" logo. Corporations will see better income from the implementation of this project, and will also be exempt from the public scrutiny of their fishing methods which has given them such a bad image. Environmentalists on the other hand, who might be willing to fund and care for the speakers, would be able to advance their cause by saving sea mammals.
Conclusion: A Better World Community
The only way that this project can succeed is if the first step is taken; full implementation of the project is beyond the scope of this proposal. What is needed is the drive, the desire to help these graceful creatures. This project has highlighted some of what is already known of dolphin behavior and focused on the need for dolphin protection. Research supports the idea that these are mammals with emotion. They form friendships and care for children in a similar manner to humans; they try to save each other from the nets by making futile attempts to bite through them. Presumably, dolphins regard death with the same sense of finality that humans do, or they would not try to save each other. Yet they cannot save themselves, they need our help. This project is not intended to cater to environmental groups, nor to improve corporate public image, but as a means to save dolphins.
As a community of humans we must recognize that we are merely a subset of a much larger world community, including the other inhabitants of this earth. These creatures do not exist solely to serve our needs, and cannot be discarded as unimportant and unavoidable losses in the course of "normal" business practices. In our estimation, this project can play a key part in that "first step" towards the betterment of the world community. u