‘Magnetic maps’ guide sharks at sea: 3 stories you may have missed

© Shawn Heinrichs

Editor's note: News about conservation and the environment is made every day, but some of it can fly under the radar. In a recurring feature, Conservation News shares three stories from the past week that you should know about.

1. Sharks can navigate via Earth's magnetic field, study confirms for the first time 

A new study may reveal why sharks are so good with directions. 

The story: Migrating across vast swaths of the sea, many shark species return to the same ocean area each year in search of food or mates. But unlike humans, sharks don’t need a GPS to guide the way — it turns out they have a magnet-powered map in their head, according to a new study

Research shows the Earth is essentially a huge magnet — and every place on the planet has its own unique magnetic signature, which is what guides the needles of a compass. To test the “internal compass” of bonnethead sharks, scientists placed a group of this species in a tank and manipulated the magnetic current running through it. The sharks responded by redirecting their movements, confirming that they depend on magnetic fields to find specific locations, reported Tim Vernimmen for National Geographic. 

The big picture: Despite their excellent sense of direction, sharks can’t hide from human threats: Some shark populations have declined by up to 70 percent since 1970 due to overfishing and pollution. However, experts say that learning more about where sharks migrate — and how they get there — could help identify new oceans areas that are important for protecting this apex predator. 

Read more here


For climate change adaptation, dirt is in demand.

The story: As sea levels rise, seaside communities around the world are rapidly working to shore up their coastlines to prevent flooding by building levees — natural walls to regulate water levels — and restoring coastal ecosystems such as wetlands and marshlands. But both of these projects need dirt — and lots of it, writes Lauren Sommer for NPR.

The problem: "The demand is way beyond what the supply is," said Pat Mapelli, a land use manager for a construction materials company, in a recent interview with NPR. Typically considered waste or the useless byproduct of construction products, dirt is often dumped into landfills or discarded, rather than transported to help support restoration projects, Mapelli added. 

The big picture: As climate change accelerates, experts say it is crucial for coastal regions to start managing their dirt more effectively — rather than simply disposing of it— to build up more barriers for their coastlines.  

"We're on the precipice of a huge crisis," Letitia Grenier, senior scientist at the San Francisco Estuary Institute, a water and ecology think tank, told NPR. 

"If we act now, we actually have enough sediment from other sources to keep our wetlands and to keep protecting our shorelines. But if we keep doing business-as-usual approaches, we're going to be in really big trouble."

Read more here

The COVID-19 pandemic forced many fishers to stay at sea for months. 

The story: When countries in Southeast Asia shut their borders during the pandemic, many migrant fishers were stranded at sea, reported James O’Donnell for Hakai Magazine. Prohibited from docking on land or major ports, these fishers were often deprived of medical care, visits to their family and opportunities to lodge labor or wage complaints to governments, leaving them more vulnerable to human rights abuses.

“Because of the pandemic we couldn’t travel,” Aung Aung, a Burmese fisher living in Ranong, Thailand, told Hakai. “I miss my family. I miss the Burmese food, since I don’t like the meals on the boat too much. I really miss home.”

The big picture: In recent years, journalists and researchers have uncovered slavery, child labor and human trafficking on fishing vessels, spurring a global push to address human rights abuses on the high seas. Now reports show that the pandemic has exacerbated these issues, putting fishers at greater risk of human rights violations. 

According to Elena Finkbeiner, a fisheries expert at Conservation International, countries must invest more resources toward creating and applying policies that protect small-scale and migrant fishers both at sea and on land. 

“In the short-term, governments, NGOs and other actors need to help these fishing communities get the resources they need to weather the pandemic, including access to food, relief funds, personal protective equipment and assistance programs,” she said in a recent interview with Conservation News. “As a global community, we can all do our part to mobilize resources and support for small-scale fisheries, which are crucial for food and livelihood security around the world.” 

Read more here


Kiley Price is a staff writer at Conservation International. Want to read more stories like this? Sign up for email updates here. Donate to Conservation International here.

Cover image: A group of sharks in New Caledonia (© Shawn Heinrichs)

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