A new map is giving ocean researchers and advocates a powerful tool to protect sharks. (Photo Credit: Global Fishing Watch. 2018. globalfishingwatch.org)

New map could protect sharks from commercial fishing

Data and technology could potentially save millions of sharks each year.

Each July, the world stops for a week to appreciate one of the most efficient and ruthless hunters in the animal kingdom. Sharks truly are amazing creatures. Their torpedo-shaped bodies and lightweight, cartilaginous skeletons allow them to swim long distances with minimal energy. Their multiple rows of teeth continuously replace themselves throughout a shark’s life. Sharks even locate their prey by detecting the tiny electrical signals in the water given off by fish and marine mammals. They are so effective, in fact, that their basic body plan hasn’t changed much in the 400 million years they’ve been on Earth.

Sadly, like so many animals, there is increasing pressure on shark populations. Offshore commercial fishing lanes are overlapping with shark-infested waters, putting them at greater risk of being killed by fishing boats. But marine biologists have built a new tool that could help protect sharks.

Tiger sharks and just one of many amazing shark species that are at risk from commercial fishing. (Photo Credit: Wikipdia)

Blood in the water

Over the last six years, researchers from across the Eastern United States working with the nonprofit Oceana have caught and tagged open-ocean shark species. The satellite-linked tags allow researchers to keep track of the movement of species such as blue sharks, hammerheads, and tiger sharks. That is then data overlaid with the tracking systems on fishing vessels, showing where commercial fishing lanes and groups of sharks intersect.

Global Fishing Watch, an international non-profit dedicated to protecting ocean ecosystems, uploaded the shark migration data along with the positioning systems on commercial fishing vessels. The result is a beautiful interactive map that shows the locations of both sharks and fishing areas over a 14 month time frame. The maps shows what most researchers have long suspected, that commercial fishing lanes are overlapping with sharks, who are likely looking for the same schools as the fisherman.

The different colored lines on the map show movement of sharks that have been tagged. The light blue shows areas of commercial fishing, which overlap with where sharks look for food. (Photo Credit: Global Fishing Watch. 2018. globalfishingwatch.org)

There’s a lot of danger for sharks in running into commercial fishing grounds. While coastal waters provide sharks and other fish species more protection, those regulations are not extended to the open ocean where most large-scale fishing occurs. The boundaries between where it is legal to fish and where it is prohibited follow points on a map, not shark habitats. When the sharks do encounter fishing vessels, they are likely to be killed. Nets do not discriminate between fish species and sharks looking for potential meals may end up eating food with fish hooks, even if they were not the type of fish intended to be caught.

Illegal fishing is a danger as well. While most countries have laws against overfishing, they are hard to enforce on the open ocean, where fish and sharks alike can be caught and sold on the black market. Shark fin soup is a delicacy in parts of Asia, selling for as much as $100 a bowl. This has led to a practice known as shark finning, where sharks are caught, their dorsal fins cut off, and are thrown back into the water while still alive, a death sentence for the shark. Without its dorsal fin, a shark cannot swim effectively and will sink to the bottom of the sea, dying from suffocation.

Shark finning is a brutal and illegal practice. The picture above shows an NOAA agent countinig confiscated shark fins. (Photo Credit: Wikipedia)

These dangers have taken a heavy toll on shark populations worldwide. A 2013 study by Dalhousie University in Halifax Canada conservatively estimated that 100 million sharks are killed each year either accidentally or by illegal fishing practices. Numbers this large threaten the long-term stability of several shark populations, many of which are vulnerable because sharks take a long time to reach reproductive maturity and generally have only a few offspring.

Trouble at the top

Outside of the tragic possibility of losing one of the most magnificent animals on Earth, there are real dangers to declining shark populations. Sharks are apex predators, animals at the top of the food chain who have no other species hunting them. These animals are important for ecosystems, they keep the populations of their prey and smaller predators down and create a more robust ecosystem. Scientists call this trophic cascade, where the presence of top predators provide benefits throughout a food web. If shark populations begin to tank, the populations of other predators would grow, putting a lot of pressure on species further down the food chain. The enormous range of some shark species could also magnify the damage across many thousands of miles.

Apex predators, such as sharks, provide benefits throughout all trophic levels in a food web. (Photo Credit: Science Over Everything)

But new tools such as the map build by Global Fishing Watch is giving researchers better insights into shark behavior and ocean advocates more effective tools for conservation. Being able to show field data on how close the interactions between humans and sharks really are could potentially lead to new policies such as restricting fishing lanes when large groups of sharks in the area and more sustainable fish management overall. Illegal fishing, which has been so challenging to oversee, could potentially be contained. The map syncs with the automatic identification system used on large ships to broadcast their position to avoid collisions. This could allow governments to keep better tabs on where fishing vessels operate and crack down on illegal operations.

Hopefully with better tools and technology, we can protect shark populations and celebrating Shark Week for years to come.

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