Everything You Need to Know About Endangerment and Basking Sharks

“Every day up to 150 species are lost”

- U.N Convention on Biological Diversity

Many ecologists believe that the world is currently experiencing the 6th mass extinction. The rate at which humans are impacting the Earth is almost equivalent to the extinction event that wiped out the dinosaurs. There are almost 17,000 endangered animals on Earth: if these animals are not protected, Earth will never recover. This article will examine what extinction is at a deeper level and will discuss the endangered shark species: the basking shark. From its ecological niche to its appearance and cause of endangerment, this article will tell you everything you need to know about basking sharks and extinction.

First, What is extinction?

A species is extinct when no more individuals of that species are alive. Extinction can happen to a species if the rate of individuals being born is less than the individuals dying or if there is a loss of genetic variation in the population (Rutledge et al., 2011). Environmental factors like the destruction of habitat, overhunting, global warming, and natural disasters can also accelerate extinction (Gittleman, 2020). Additionally, human interference also puts animals at risk of extinction. When certain criteria are met, these species at risk are considered endangered (Museum of Natural History, 2006). The IUCN states that a species is endangered if its population has decreased 50% or more over 10 years, has less than 2500 mature adults, only occupies a small area or there is a prediction that the species will be extinct in the next 20 years (Hogeback, n.d.). In the case that a species does become extinct, their ecosystem may change in drastic ways. For example, other species that were dependent on the now extinct species may also begin to decrease in population. As Forest Isbell of Iowa University states, “contemporary biodiversity declines will lead to subsequent declines in ecosystem functioning and ecosystem stability” (Isbell, 2010). Furthermore, David Button, a Natural Sciences postdoctoral research scholar, states that extinctions can impact the “distribution of animals and ecosystems, or biogeography” (North Carolina State University, 2017). Ecosystems are often dependent on having a variety of species, and as diversity decreases, ecosystems are more likely to become unstable (Isbell, 2010). Although extinction initially reduces ecosystem variation and stability, it creates more room for the surviving species to thrive. Niches are left vacant after species become extinct, giving other species the chance to diversify and potentially evolve into something new. Some populations may succeed due to an increase in available resources and could later fill the roles left behind by extinct species: the extinction of species allows previously insignificant species to become more dominant by giving them the chance to evolve into vacant niches (University of California Museum of Paleontology and National Center for Science Education, n.d.). Extinction may cause less diversity, but it can also create new opportunities. As stated by National Geographic, “By making room for new species, extinction helps drive the evolution of life” (National Geographic Society, 2019).

Let’s Learn the Basics of the Basking Shark

The scientific name of the basking shark is Cetorhinus maximus. It is part of the order of sharks commonly called mackerel sharks that includes the Sandtiger, Shortfin Mako and Porbeagle (Rigby, C.L et al., 2019). Basking sharks are the second-largest shark after the whale shark and usually live about 50 years. They are greyish-brown and can grow up to 12-15 meters, but most are between 7-9 meters long. Their large gill slits and body size makes them distinguishable. Furthermore, the tail of the basking shark is a unique crescent shape, and their mouths can be 1 meter wide (Fisheries and Oceans Canada, 2018). These gentle filter-feeders are usually spotted at the surface of warm waters, but they can occur between 200-1500 meters deep (Fisheries and Oceans Canada, 2019). More specifically, basking sharks are found in warm, coastal parts of the Atlantic and Pacific oceans (Rigby, C.L et al., 2019) and their movement history suggest a migration pattern impacted by seasons (Fisheries and Oceans Canada, 2019). Moreover, basking sharks get their name from the way they eat because it resembles basking. They swim slowly at the surface of the sea while opening their giant, cone-shaped mouths, and bristlelike structures called gill rakers filter the water they swallow for zooplankton (Fisheries and Oceans Canada, 2018). Because basking sharks are massive and are at the top of the food chain, they do not have many natural predators. Besides humans, the great white shark and orca are two of few threats to the basking shark (AZ Animals Staff, 2020). To add on, basking sharks are social animals as they are seen alone or in groups. When they are in groups, they tend to be separated by size and gender, suggesting division within the species (Shark Trust, 2020). As of 2018, the IUCN stated that basking sharks are an endangered species with about 20,000 mature sharks alive in the wild. Furthermore, other data show that the population number is fluctuating. Current research shows that the modern population has shrunk to less than 30% of past recordings. By addressing the cause of endangerment and providing solutions to increase their numbers, basking sharks can return to their former glory.

Why are Basking Sharks Endangered?

Human actions are one of the leading causes for the endangerment of basking sharks, but there are also environmental factors contributing to their decrease in population. To start, basking sharks have an inherent low biological productivity and are slow to reproduce. Female gestation periods take at least three years, and it only results in a few offspring (Oceana, n.d.). Not only do basking sharks reproduce slowly, but they also face other challenges in survival. Global warming has caused ocean temperatures to rise, resulting in fewer places with adequate oxygen. Furthermore, plastics heavily pollute ocean regions which dirty and destroy basking shark habitats (Stokstad, 2015). Pollution also makes it harder for basking sharks to find zooplankton to eat as trash may intercept a basking shark’s feeding path. Besides the destruction of their environment, human interference is the foremost cause of basking shark endangerment. In the past, basking sharks were hunted for oil, entertainment, and their fins. They used to be in high demand which resulted in them nearly being wiped out. There was also a time when fishers specifically targeted basking sharks as they were considered a nuisance. This eradication program eliminated many sharks and left an immense impact on the size of the current population (Fisheries and Oceans Canada, 2018). To add on, basking sharks are also victims of bycatch and were fished without regulations for many years. Ships and other sea crafts also harm basking sharks because they cover the ocean’s surface (Davenport, 2016). Because of the destruction of their environment, human interference and their innate slow rate of reproduction, the basking shark population is decreasing. Now, there are regulations and fishing laws that ban the finning of any shark species, and the Fisheries Act also protects them from being hunted (Fisheries and Oceans Canada, 2019). Moreover, organizations and charities heavily monitor basking sharks and try to ensure their safety. Other things that would benefit the repopulation of basking sharks are reducing global warming, fighting climate change, cleaning oceans, finding eco-friendly ways to fish, and reducing the number of boats in oceans. Furthermore, reducing the demand for shark products will decrease the fishing of sharks and prevent fishing waste from entering the oceans.

What Will Happen if the Basking Shark Goes Extinct?

(Adaptive Radiation)

Adaptive radiation is when an organism evolves into numerous new species, well adapted to certain conditions (Editors of Britannica, 2020). According to the book Biology in Focus, adaptive radiation is a “period of evolutionary change in which groups of organisms form many new species whose adaptations allow them to fill different ecological roles in their communities” (Urry, 2017). Extinction is one of the major causes of adaptive radiation because when species go extinct, niches become vacant for surviving animals to evolve into. A closely related species that shares a common ancestor with the extinct animal is most likely to evolve and fill that space (Editors of Britannica, 2020). Sharks play a fundamental role in the ocean food chain and in maintaining the ocean’s health. If no apex predator is maintaining the populations, there would be an imbalance of resources and food (Griffin et al., 2008). Sharks create and regulate biodiversity in the ocean, and without them, fish would ultimately starve because there would not be enough resources to sustain their populations (Weisberger, 2019). Evidently, sharks are crucial for healthy oceans so, if basking sharks went extinct, another animal would most likely quickly fill the role. Due to the extinction of basking sharks, zooplankton and fish populations would likely grow. This increase in food may attract predators to move. One of the animals most likely to fill the role of basking sharks would be the whale shark. As they are both sharks and filter-feeders, there would be a high chance that whale sharks could evolve to fill the empty niche. Furthermore, whale sharks and basking sharks share similar habitats and living locations. Whale sharks tend to live in tropical, coastal, warm water and are known for traveling long distances to find plankton (WWF, n.d.). They also live at the same sea levels as basking sharks. Besides that, whale sharks often migrate, therefore, some could branch off from the rest of the population and begin living where basking sharks were (Norman, n.d). The giant squid may also be likely to adapt to the role of the basking shark. The giant squid lives in the same parts of the ocean as basking sharks, but they tend to live at much deeper sea levels (Ocean Conservancy, 2019). They don’t eat zooplankton, but because there could be more zooplankton, the amount of fish may increase as well. It could be possible that giant squid could evolve to live at higher depths because, without the basking shark, there would be more food in those areas. So then, surviving in the areas where basking sharks were would be easier for the giant squid.

Summary

In this article, extinction was defined as the disappearance of an entire species. When a species has no more living organisms, it is extinct. A species is endangered if it is at risk of extinction. If species do go extinct, it will initially damage the ecosystem and cause less biodiversity, but it will also be an opportunity for other animals to evolve into new species. Basking sharks are giant filter feeders that eat plankton in coastal, warm areas of the ocean and are apex predators. They are an endangered species due to the destruction of their habitat, their slow reproduction rate, overfishing, and human interference. Changing the way humans fish and reducing the demand for shark products can help protect this species. When animals go extinct, there is a high chance that other species may evolve quickly to fill the vacant niches in the ecosystem. This varied adaptation is called adaptive radiation. If basking sharks went extinct, the whale shark or giant squid could be the most likely candidates to evolve and replace basking sharks because of similar habitats and diets. Humanity is destroying Earth faster than it can recover. We need to do our part to ensure that animals like the basking shark don’t disappear. Humanity can prevent the 6th mass extinction event if we spread awareness and do our part.

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