Population Linkages of White Sharks Essay
Population Linkages of White Sharks
Our marine environment is yet to be explored. Human knowledge about the sea and the ocean is only very little as compared to their knowledge on the universe. A lot of creatures, both small and big, still need to be investigated and discovered. Many animals is found in the ocean, some are friendly and some are not, some needs more research while others do not as it is already established. The great white shark, Carcharodon carcharias, is one of the most misunderstood among the many marine vertebrates.
Information on this animal is scarce as research on this organisms is only limited. The great white shark is often feared by many people including researches as it is one of the most ferocious and dangerous animals in the world. Studying sharks entails a lot of courage. According to Martin (n. d. para. 2), “observing shark behavior in the wild is fraught with inherent logistical challenges”. Majority of the shark species including the great white shark are fast moving and elusive fish and are usually found in the depths of the ocean though some thrive near the reef.
With this kind of behavior, studying sharks is one great task. But with the decline of this species, many researchers have been challenged to conduct more research about these elusive animals. To make appropriate management solutions one must clearly understand the behavior of an organism which includes but not limited to its feeding behavior, migration behavior, mating and reproductive behavior, physiology, adaptation, population, distribution, diseases and many more.
In this study, the large-scale spatial dynamics and population structure of white sharks is investigated. The mentioned behaviors are greatly needed for the proper management and conservation of white sharks but these behaviors are poorly understood because researches have been limited because during the past years, sophisticated instruments that are currently used to study this behavior are not available. There have been conflicting ideas on the behavior of great white shark.
Males are assumed to move between distant populations, whereas females have been assumed to be nonroving and philopatric (Bonfil, Meyer, Scholl, Johnson, O’Brien,Oosthuizen, Swanson, Kotze, Paterson, 2005, p. 100). With the current decline in the number of great white sharks, better understandings on the distribution and migration behavior of white sharks are important tools for the proper management and conservation of the said species. Appropriate knowledge on the behavior of white sharks is highly beneficial, both to the organisms and humans.
This study contributed to a better understanding on the transoceanic migration, spatial dynamics, and population linkages of white sharks. To study the spatial dynamics of white sharks, the researchers tagged white sharks off the Western Cape of South Africa between June 2002 and November 2003 with pop-up archival satellite transmitting (PAT) with 25 sharks being tagged; near-real-time satellite tags with seven individuals; and acoustic tags with 25 white sharks tagged (Bonfil et al. , 2005, p. 100). Tagging would enable the researchers locate where the sharks are going.
Aside from these, the depths and temperature and other important parameters at which the shark usually stays during the journey is also recorded. Complex spatial dynamics in white sharks were revealed using Electronic tagging and photographic identification. This dynamics were categorized into four kinds of behavior which includes rapid transoceanic return migrations, frequent long-distance coastal return migrations, smaller-scale patrolling, and site fidelity (Bonfil et al. , 2005, p. 100). Patterns of migrations that were recorded using the tags were the basis for these behaviors.
Transoceanic return migration involves a return to the original capture location, dives to depths of 90 meters and the tolerance of water temperature to as low as 3. 40C (Bonfil, 2005. p. 100). This kind of behavior was not thought to exist in great white sharks. This study proved direct evidence that this kind of activities is also present in great white sharks. Furthermore, this study also altered the previous speculations that female white sharks are not capable of transoceanic return migration.
Frequent long-distance coastal return migrations were observed when the great white sharks travel from Western Cape to waters as far as 92,000 kilometer away off kwaZulu-Natal and beyond , with the use of underwater routes along the continental shelf, then return to their original tagging sites off the Western Cape after four to six months (Bofil et al. , 2005 p. 100). Furthermore, smaller-scale patrolling, and site fidelity behavior were observed base on the patterns of their migration (Bofil, 2005. p102).
White sharks were always observed to be swimming within its territory and it always returns to its tagged site. As a conclusion, the data gathered by the researchers did not clearly explain the linkage between populations of white sharks. There discoveries needs further research to further claim their results. According to Bofin et al (2005, p. 103), “multidisciplinary studies integrating population genetic analyses and electronic tagging, as well as the development of improved monitoring instruments, should be encouraged”.
This study is a good research with new discoveries and breakthroughs about white sharks. The data were clearly presented and explained. The graphs and figures were also clearly explained and were also clear. The graphs can be easily understood. However, there was only a little background on the characteristics of the white sharks. Brief and concise background information would be valuable especially to those who don’t have background on white sharks. The article was written in a very concise and brief manner and very direct to the point.
But despite its conciseness, the data were still presented in a way that is easily understood by the readers. The data being presented in the article were able to meet its objective on adding information on the large-scale spatial dynamics on white sharks but it wasn’t able to give details on the populations of white sharks which were, however, attested by the researchers. According to the authors, Bofil et al (2005, p. 103) “Our studies show that we do not have a full understanding of the ways in which identified populations are connected”.
But despite this, they were still able to discover new things about the white sharks like the transoceanic return migration behavior of the white sharks. Strong points of the paper are the clarity of its presentation and the straight-to-the-point explanations. Furthermore, the length of time in data gathering is also another strong point for the paper. The data collection run for more than a year and covered the entire migration pattern (from the start to the end) of the white sharks. This also made the data more convincing and reliable.
Furthermore, a DNA test would also aid the researchers to know if there are population linkages of white sharks. However, this gathering of DNA would be a little bit difficult as it will require some flesh samples the white sharks which makes it more dangerous as the shark might react heavily on this. So far, the most invasive way to link the population of white sharks is through tagging. It lessens the danger that the researchers might encounter. Base on the results of this study, precautionary measures on white sharks can be established.
Moreover, the results of this study can also aid conservation groups and countries in setting up laws and treaties on this threatened species. Bofil et al. , (2005, p. 103) made mention that “long-distance and transoceanic migrations expose great whites to increased risk of mortality as they leave domestically protected waters in South Africa/Australia and travel into neighboring or remote countries, sometimes located across entire ocean basins”. The increasing demand for shark products has caused most shark species to decline over the years.
Thus, the need for us to protect white sharks since they are one of the top predators in the ocean and a loss of such predators might cause imbalance to the ecosystem leading to an increase in other fish and mammal populations. Putting everything into the above context, this study made an excellent contribution on the behavior of white sharks. A few improvements on this study would certainly help conservation groups and countries in conserving the white sharks.
Bonfil, R. , Meyer, M. , Scholl, M.., Johnson, R. , O’Brien, S. , Oosthuizen, H. , Swanson, S. , Kotze,D. , Paterson, M. , 2005. Transoceanic Migration, Spatial Dynamics, and Population Linkages of White Sharks. Science 310, 100 (2005); DOI: 10. 1126/science. 1114898. Retrieved on April 5, 2007 from http://www. sciencemag. org/cgi/reprint/310/5745/100. pdf. Martin, A. n. d. Mental Processes of White Shark. ReefQuest Center for Shark Research. Retrieved on April 6, 2007 from http://www. elasmo-research. org/education/white_shark/mental_process. htm.