What If Every Shark Disappeared?

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As apex predators, sharks play a vital role in the ocean ecosystems. Every year 100 million sharks are killed by humans and that number is only increasing. As human activity continues to put sharks in critical danger, it makes scientists wonder: What would happen if every shark on the Earth disappeared today? The answer is very scary.

VIDEO: What If There Were No Sharks?

Coral Reefs Would Disappear

Coral Reef

A study published in PLOS ONE in 2013, showed that sharks were crucial for the health of coral reefs. Coral reefs have an delicate ecosystem balance. Algae grows on coral, which is eaten by herbivorous fish. Herbivorous fish are then eaten by larger predatory fish which are eaten by sharks. When sharks are in decline, less of the large predatory fish are eaten, which means that more of the herbivorous fish are eaten, and in turn, less of the algae is eaten. The algae competes directly with the coral, and too much algae kills coral reefs. After studying 185 miles of coral reef, the information on sharks the scientists found showed that declining shark populations as result of overfishing have had disastrous impact on coral reefs. So if all sharks disappeared, coral reefs would also vanish.

VIDEO: If We Lose Our Sharks, We Lose Our Ocean

The Ocean Would Suffocate

What If Every Shark Disappeared?

Another problem as a result of this imbalanced food chain noted in coral reefs, is that the excess growth of algae blooms would suffocate the ocean. Algae blooms suck the oxygen out of the water creating low oxygen levels. Without oxygen, marine life will suffocate to death. This is a phenomenon that has been observed worldwide in both oceans and freshwater. Also, some algae blooms can also produce toxins that get into the water. These toxins are incredibly harmful to marine life and can lead to mass die-offs. Algae can also be very toxic for people. Without sharks to keep the herbivorous fish populations in balance, the oceans would suffocate from algae blooms.

Marine Species Would Face Extinction

jelly fish

Another major consequence if sharks disappear, is that many marine species would face extinction. This happens for two reasons. One, sharks often prey on the weak or ill members of marine life. These weak and ill members are easier to catch than strong, healthy members of a population. If the weak and ill members continue to thrive, it will weaken the larger population. First because they could potentially spread illness to the other members of the population, which could lead to massive die-offs. Secondly, because when these weaker members of the species are allowed to reproduce, it weakens the genetic makeup of the species as a whole, putting them at risk of extinction.

The second reason marine species would face extinction is because when sharks are not around to consume other predators, those predator populations grow exponentially. Meaning, their prey is at risk of being over-consumed. This was observed in 2007 in the Northern Atlantic where sharks had been overfished. Sharks preyed on bullnose rays, that preyed on scallops. Once the shark populations declined, the population of bullnose rays grew and ate all the scallops. This lead to a collapse of the species. So if sharks disappear, then so do other marine life.

The Speed Of Global Warming Would Increase

Global Warming

The oceans help regulate the carbon cycle of the planet. Coastal ecosystems store about 50% of the world’s carbon. Sharks are a crucial factor in keeping that carbon stored. The carbon is stored in marine plant life, and without sharks many of the animals that eat these plants would no longer face a predator threat. So their populations would grow and end up consuming too many of these plants, releasing a flood of carbon into the atmosphere. Further, as physically large predators, sharks hold a lot of carbon in their bodies. When they die, they sink to the bottom of the ocean where they move the carbon from the surface to the seafloor. Their bodies are then eaten by scavengers, keeping the carbon out of the atmosphere. Without sharks, carbon levels would jump, speeding up the rate of global warming and climate change.

The World’s Economy Would Collapse

Stock Collapse

The global commercial fishing industry employees 200 million people and generates upwards of $90 billion dollars annually. If sharks were to disappear, there would be a massive collapse in the ocean’s food chain. A collapse that would dramatically impact the commercial fishing industry. Between reduced animal rich habitats like coral reefs, declining and extinct populations, and algae blooms creating toxic fish, commercial fishing would be destroyed–not to mention all the negative economic impacts of dramatically increased climate change. That means millions of people who make their livelihood from commercial fishing would lose their incomes. This would be a disaster for the world’s economy. So if sharks disappeared today, so would the $90 billion commercial fishing industry.

Diseases Could Go Uncured


Reducing biodiversity has a huge impact on medicinal science. Scientists use information on sharks to help diagnose, understand, and treat many illnesses and disease that impact humans. For example, in 2011 scientists found an antibiotic in shark liver that could treat a broad range of viruses from dengue and yellow fever to hepatitis. Scientists are also studying anticlotting compounds in shark blood to treat heart disease. There is also ongoing optometric research investigating the possibility of cornea transplants from sharks to humans. Furthermore, sharks are being studied to help understand and treat everything from alzheimer’s disease to cancer to HIV. Sharks may hold the key to treating and curing many illnesses that impact humans. If sharks disappeared today, these illnesses could go uncured.

Sharks are an incredibly important part of our ecosystem. If shark populations were disappear today, there would be disastrous consequences for the oceans, our environment, and human life. It is essential that we work to protect these crucial apex predators, so that we can keep the planet in balance.

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