Our waste is hurting one of the seas biggest helpers – sharks. Yes, you read that right!
These are an ancient group of fish that have inhabited our seas long before people were around and even before trees existed on land! However, their population numbers are falling significantly. So what’s going on, and why should we care? Shouldn’t we be glad that another big scary ocean predator is less abundant?
Spoiler alert: No! Sharks are vital to our marine ecosystems!
The Crucial Role of Sharks
Sharks have been in our oceans for 445 million years. To put that into perspective, that’s older than the dinosaurs, and even before insects were around! This has given them time to evolve into a huge variety of shapes and sizes to fill different ecological niches, from enormous filter feeding whale sharks, to agile hunters like great whites. Some have even evolved into very strange shapes, like the famous hammerhead shark, or the flat ‘carpet’ sharks like the angel shark, and one of my personal favourites, the wobbegong!
All these different species have an important role in their eco-systems. Sharks act as guardians for their respective marine habitats, as many species are predatory, they play an important part in controlling healthy populations of fish, marine invertebrates, mammals, birds and the many other different organisms that call the oceans their home.
This helps maintain balance in the population of marine life. If there were fewer sharks, certain fish species may grow over-populated. This can exhaust food supplies of smaller fish or marine plants. They also maintain biodiversity. As predating on a variety of creatures, sharks help stop certain prey species becoming more dominant than others and remove unhealthy and sick animals from the population.
All of this hungry work done by the shark, is also part of the crucial cycle of carbon storage. They help to lock away carbon which is changing our climate, by passing it through the food chain.
Today, many species of sharks are what scientists call ‘indicator species’. These are species which when present in an ecosystem, highlight its health. They show the environment is clean enough and has enough food to sustain these large predators. An ecosystem which could be a home to a shark, where none are now present, may be considered polluted or damaged.
Homeless and hunted: Sharks Biggest Threats
Sharks are now fighting for their ecological survival. Since 1970, the global abundance of these predators has declined more than 70 percent, and half of shark species are considered endangered or critically endangered. A potential extinction catastrophe!
The most cited killer of sharks, is overfishing, especially by-catch, where nets scoop up tonnes of fish, and inadvertently sharks as well, many of which perish in the process. The problem doesn’t stop there, however, abandoned or lost fishing gear, such as nets and lines, continue to catch marine animals when they are damaged or disposed of at sea.
This is also known as “ghost fishing.” Sharks that get entangled in these abandoned bits of gear, lead to injury, immobilization and death. Worse still, sharks are drawn to these silent killers by the struggle and smell of other stranded marine animals, only to be ensnared themselves. Fishing line and nets, can take hundreds of years to break down, and now constitute a significant part of ocean plastic waste, with football field-sized nets currently adrift in our oceans.
Commercial waste however, is not the only killer. Marine plastic pollution from our throwaway society is also causing the death of sharks through ingestion either by themselves or the fish they hunt. From plastic bags to water bottles, our personal waste are killing sharks who see these items seen as prey. This results in physical harm, blockages, malnutrition, and even death. Contaminants from the breakdown of plastics also affect sharks directly with health issues, including hormone problems, immune system suppression and impaired growth!
Sharks are also losing their homes in the ocean the destruction of their habitats. Plastics and microplastics can lead to the premature death of many of the sharks’ prey species, corals, seagrasses and kelp they depend upon. Worse still, the breakdown of these plastics releases harmful chemicals into the sea further affecting these habitats, with ocean acidification drastically harming the health of coral reefs which provide habitat for a large variety of marine life.
Where do we go from here
If populations of sharks continue to decline, many will face extinction. This could bring about great problems for the marine ecosystem at large. Their loss will affect the income of small coastal communities that depend on them for tourism or those taht rely on healthy marine fish populations for food.
We can help sharks by buying reusable items and avoiding single-use plastic. We can also ensure we dispose of any waste sustainably, by recycling or using appropriate waste bins. If you eat fish, try to buy only sustainably sourced sea food. Preferably, pole caught fish, which limits by-catch and avoids supporting large net-based fishing methods.
Sharks have had a bad press as people killers and hunters. Whilst shark attacks do happen, these are very rare. Many great white attacks have occured due to mistaken identity. Humans being taken for their common prey items like seals. Shark attacks like these are incredibly rare, in fact so rare, there is a 1 in 11.5 million chance a bather is attacked by a shark!
So, if you have read this article, and others like it, share them! Sharks are fascinating creatures who need our help and we can only do this once everyone knows about their importance to our seas and the threats they face. Changing the opinion of sharks is also crucial. They are not blood-thirsty killers, but important guardians of the marine ecosystem, and without them the seas would be far worse off.