Course:CONS200/2019/Climate Change Impact on Great White Sharks: Conservation Implications

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Introduction

A Great White Shark swimming near Guadalupe Island, Mexico. By Elias Levy. Public Domain.

Following decades of rapid industrialization and rising global greenhouse gas emissions, severe environmental disturbances in marine ecosystems have gained momentum at a global scale. This human-led devastation has caused the global state of biodiversity to deteriorate at an alarming rate[1]. The consequences of this can be observed in the declining populations of many marine species, such as the Great White Shark (Carcharodon carcharias). Specifically, climate change and ocean acidification have caused severe distortions to the natural habitat and behaviours of the Great White Shark. Consequently, conservation efforts are essential in order to salvage the depleting shark populations and ensure the survival of this species. Currently, scientists are focusing their efforts on reducing the human-induced damages impacting the shark's natural habitats. Further political, social, and legal remedial actions must be executed in order achieve the end goal of conserving the Great White Shark. In addition, conservation efforts must consider additional pressures, such as commercial fishing, that are contributing to the demise of this powerful predator.

Pressures on Great White Shark Populations

Climate Change

Climate change is defined as the human-driven distortion of the Earth's climate and atmosphere, primarily caused by the emission of Greenhouse gases[2]. Further knowledge surrounding its existence and impact on the environment has led geologists to propose our emergence into a new epoch: The Anthropocene[3]. Its designated name further labels humans as a geological force as it is derived from the word "anthropo", which means man, and "cene", the suffix for epoch. The Anthropocene, which began in the 1800's is characterized by the expansive use of fossil fuels, and increased concentrations of Greenhouse gases in the atmosphere. This has led to, and continues to cause, long-term environmental consequences at a global scale.

Alarmingly, scientific research has shown that climate change is leading to a plethora of issues relating to the environment; one of which is the considerable impact it is having on multiple ecosystems, hence affecting a vast array of flora and fauna[4]. Through research, scientists have found observable alterations to the habits of many plants and animals, such as distortions in their respective populations, genetics, migration patterns, and anatomy[4].

In regards to marine ecosystems, It has been found that oceanic temperatures have increased by roughly 2.5°C when compared to the previous glacial transition, which occurred 20,000 to 10,000 years ago[5]. Of this 2.5°C, 0.7°C occurred between the years of 1870-2005[5]. This rise in temperature occurs as the ocean takes up 93% of the heat created through anthropogenic means[5]. Further, research has shown that oceanic temperatures are expected to continue to rise[6]. A recent report estimates that a rise of between 2.6°C and 4.8°C will occur by the year 2100[7]. This would result in severe implications for the organisms inhabiting its various complex ecosystems[6], such as the Great White Shark.

How Climate Change Affects Great White Sharks

As a result of the changing oceanic environment, Great White Sharks have displayed alterations to their natural behaviours and abilities. For instance, a study performed by a team of South African researchers found that oceanic temperatures impact the movement patterns of adult female and male shark populations. Specifically, they observed that during warmer water years, more female white sharks are observed in coastal regions, and during colder water years, more males are seen[8]. Therefore, as Oceanic temperatures continue to gravitate towards warmer conditions, differences in migration among sexes can result in their segregation, as less males visit the areas where females reside. This can be detrimental to shark populations, as a reduction in interactions among the different sexes can reduce the probability of mating. Simultaneously, the Great White Shark’s low reproduction rate and slow growth to maturity make[9] the observed phenomenon of increased sexual segregation a worrying sign, showing the potential for further population reduction.  

Ocean Acidification

Ocean acidification is the phenomenon that is characterized by a decrease in the ocean's pH levels[10]. This chemical change in composition occurs when the ocean absorbs a significant portion of all anthropogenic carbon dioxide (CO2 )[11]. Research has shown that approximately one third of this CO2  is derived from fossil fuel emissions, cement production and deforestation[11]. Consequently, these actions are modifying the climate process and inducing shifts in the ocean's pH[12]. According to scientists, this trend is likely to continue, with a further 0.4 unit decrease in the Ocean's pH by 2100[7]. However, It is important to note that "acidification" does not mean that the ocean has a pH below neutrality. The average pH of the ocean is still basic, but because the pH is decreasing, it is described as undergoing acidification[13].

The current trends in ocean acidification are responsible for the declining diversity within reef communities. As this reduction in oceanic pH continues, carbonate reef structures will fail to maintain their composition, and the marine environment will continue to deteriorate[14].

How Ocean Acidification Affects Great White Sharks

Another research study, which was performed on a variation of different sharks, looked to define the relationship between ocean acidification and warming with shark populations. The team of scientists discovered that juvenile sharks that were exposed to warmer waters and an acidic environment had significant impairments in terms of their condition and survival[15]. Specifically, they found that the shark’s routine metabolic rates and survival were significantly altered by increasing temperatures, as well as acidic pH’s.

Ocean acidification has also been shown to impair the normal odor tracking behaviour of sharks[15]. Sharks use their extraordinarily sensitive olfactory system to lead them to food sources. Therefore, if this highly important sense malfunctions under more acidic conditions, it is likely to lead to the shark finding less food and potentially starving. In addition, this same study found that sharks treated under more acidic conditions saw a decrease in their attack behaviour[16] . Consequently, they are less likely to be able to perform feeding attacks and capture their prey.

Bleached Acropora coral. By Vardham Patankar. Public Domain.

In addition, ocean acidification has led to a phenomenon called coral bleaching. This is characterized by the loss of symbiotic algae and photosynthetic pigments within coral animals[17]. Coral reefs serve as an essential habitat for many species living in oceanic ecosystems, one of which are reef fish. The degradation of coral reefs in the form of coral bleaching has caused a significant decline in the population of these fish[18]. As reef fish are an important component of a young Great White Shark’s diet, a decline in their population would likely affect the sharks[19].

The repercussions of climate change have contributed to the designation of the Great White Shark as a “vulnerable” species[20]. Evidence shows that the Great White Shark requires a delicate balance in ocean waters[21] to allow for population recovery from global warming, and fisheries[22]. However, the imbalance in the oceanic environment created by ocean acidification is severely hindering the possibility for the population restoration of this shark.

Conservation Implications for Climate Change

Current Conservation Efforts

Due to the observed decrease in Great White Shark populations, conservation scientists are attempting to protect this species from further declines.Thus far, efforts have largely centered around scientific research, and habitat conservation. In addition, large-scale efforts to combat climate change, and reduce Greenhouse gas emissions, have been implemented in the form of international agreements. These agreements to reduce the effects of climate change may indirectly improve the probability of the Great White Shark's survival.

Scientific Research

Conservation efforts in order to mitigate the effects of climate change on Great White Shark populations have slowly gained support. Specifically, the scientific community has continued working towards tracking these sharks, in order to better understand the consequences that climate change is causing[8]. Scientists hope to use the information gathered through their research in order to design strategies that promote the sustainable growth of Great White Shark populations. However, their efforts to track shark populations have failed in many occasions as a substantial portion of Great White Sharks are killed due to illegal, unregulated, or unreported activities [23].

Scientific research has led agencies to protect their habitat. For instance, the National Oceanic and Atmospheric Administration (NOAA) within the United States Department of commerce, focuses on the health of the atmosphere and oceans. Specifically, their Coral Reef Conservation Program (CRCP) aims to protect coral reefs in seven U.S states and territories[24]. Through the conservation of these areas, the Great White Shark is indirectly protected as well. In addition, there are efforts to involve citizens in restoration activities that show the relationship between the protection of coral reef and the conservation of Great White Sharks[25]. For instance, the University of Miami has local program in which researchers provide recreational divers and snorkelers the opportunity to participate in coral restoration efforts[26]. Their mission is to engage their local community through education, in hopes that they learn the important role that coral reefs play in marine ecosystems[26].

International Agreements for Climate Action

The creation of international agreements for climate action have gained prominence as the concern for the consequences of climate change continue to increase. For instance, the Paris Agreement was enacted in order to combat climate change, as well as adapt to its likely effects[27]. This international treaty calls on countries to transition from the use of fossil fuels to renewable energy[27], in the hopes of reducing climate change in the future. If successfully upheld, the reduction in the use of fossil fuels could lead to a decrease in the amounts of Greenhouse gases being absorbed into the ocean. Therefore, this could potentially lessen future ocean acidification and rising ocean temperatures. Ultimately, aiding in the conservation effort of the Great White Shark.

Options for Future Remedial Action

Although efforts surrounding the conservation of the Great White Shark exist, more action is needed in order to prevent irreversible damages to their global populations. Therefore, a combination of mitigation efforts must be implemented in the form of social, political, and legal action with the aim of creating a significant difference in their probability for survival.

Social Action

In order to protect marine ecosystems and the species that inhabit them, education and awareness surrounding the implications of current consumption habits must be disseminated. Education programs targeted at consumerist populations worldwide are essential to creating consciousness regarding their negative impacts on the environment and species[28]. Individuals must be made aware of the consequences that their everyday purchases and actions have on species, such as the Great White Shark. This will hopefully lead them to make more environmentally conscious decisions such as using more sustainable forms of transportation, reducing their energy consumption, and eating local and sustainable foods[29]. Although reducing consumption and the survival of the Great White Shark may not appear to be directly correlated, high-impact actions such as decreasing Greenhouse gas emissions through lifestyle choices will alleviate some of the pressures that the sharks are facing.

Political Action

Political action must also be taken in order to create further momentum regarding the reduction of anthropogenic emissions and recovery of shark populations[30]. This may include participation in environmental activism through attending rallies, protests, and boycotts that support the banning of toxic chemicals and the limitation of Greenhouse gas emissions[29]. Non-activist behaviours such as voting and contributing to political organizations are also important as they dictate the values that the people elected to positions of power will uphold. These political actions can lead to an increase in funding towards research pertaining to the protection of species such as the Great White Shark.

Legal Action

Both social and political actions can lead to the creation of legally binding agreements that promote the sustainable growth of the Great White Shark population. For instance, as three quarters of the world’s coral reefs are deteriorating due to environmental stresses, human-induced pressures such as urban development, pollution and mining must be reduced[31]. Governments can aid in reducing the rate of coral bleaching by creating stricter policies and multilateral environmental agreements surrounding climate change and global Greenhouse gas emissions. Specifically, governments can monitor and limit industries that are creating massive amounts of damage. This would reduce the sea temperature rise and ocean acidification that so greatly affects these reefs[31], as well as help conserve the species that require their existence, such as the Great White Shark. Therefore, a legal system which promotes the conservation of marine ecosystems can lead Great White Shark populations to recover successfully.

Additional Pressures on Great White Shark Populations

Commercial Fishing

Although climate change poses a serious threat to Great White Shark populations, commercial fishing has also been recognized as one of the main hindrances preventing them from growing to sustainable numbers[32].Therefore, these additional concerns must also be taken into consideration when analyzing the current pressures that the Great White Shark is experiencing.

Shark Products

Since the time of industrialization, the practice of over-fishing has resulted in the depletion of global fish stocks[32]. Currently, Great White Shark populations are suffering due to the rise in demand for shark products, such as jaws, teeth and fins[33]. Although there are protective laws banning people from fishing these sharks, they are not upheld at an international level. Great White Sharks are currently protected in Australia, South Africa, Namibia, Israel, Malta and the USA (California and Florida)[34]. In addition, these laws are not completely effective as loopholes can be found, and their enforcement has proved to be difficult, with shark products regularly seen on the black market[34].

By-catch

The term by-catch is defined as the unwanted fish and marine creatures that are caught in a commercial fishing expedition that is looking to catch a different species[35]. By-catch has become a very serious problem, contributing to the reduction in Great White Shark populations[35].This phenomenon has increased in occurrence due to the growing amount of commercial fishing worldwide[35].

Options for Future Remediation of Additional Pressures

In order to combat the additional issues leading to the decrease in Great White Shark populations, social, political and legal action must take place.

Social Action

A Great White Shark from the perspective of cage divers. By Horizon Charters. Public Domain.

An important element of social action involves creating awareness and educating others on the issue at hand. The tourism industry can partake in this aspect of conservation efforts for the Great White Shark. For instance, an eco-tourism company called GoEco promotes marine ecosystem education to tourists at an international level[36]. GoEco provides tourists the opportunity to cage dive with Great White Sharks, with the purpose of exposing them to a first-hand experience and then educating them on conservation efforts[36]. However, tourism companies must guarantee the protection of local ecosystems and species when building their infrastructure[30].

Political and Legal Action

A conservation technique that would greatly improve the Great White Shark populations would be to reduce the over-fishing of sharks by encouraging governments to make strongly enforced policy changes[28]. There has been a proposal to list the Great White Sharks in CITES to regulate and ban the international trade of shark products[33]. Although a CITES listing would help slow the trade of shark products, the worry of criminal black market trade would remain.

In addition, marine protected areas (MPAs) could be implemented on a larger scale to further try to increase shark populations. MPAs have the potential to achieve conservation goals by restricting fishing, and engaging with the public in education programs[37]. Currently, the Convention on Biological Diversity (CBD) is hoping to achieve their goal of having 10% of the world's oceans in MPAs by 2020. However, this will not make a difference for Great White Shark populations if the MPAs do not cover large portions of their migration routes[37].

Conclusion

In conclusion, in order to mitigate the elements leading to the depletion of Great White Shark populations far more interventions are required than one single policy change. As previously discussed, the issue of rising global Greenhouse gas emissions is a result of the growing consumerist ideals that encompass the social norms of many societies today. Our economic system continues to promote unsustainable growth and lifestyles, which are leading to a rapid loss in biodiversity[1]. Therefore, in order to conserve Great White Shark populations, a significant change in social, political, and legal systems must occur. As this decline is caused by environmental and commercial pressures, policies that simultaneously restrict Greenhouse gas emissions and protect large marine habitats must be implemented. With a reduction in these pressures, Great White Shark populations may begin to reach stable quantities in the future.

References

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