New regulations help protect whales from entanglement in fishing gear in the Indian Ocean

An adult and baby sperm whale dive down in the Indian Ocean

Tuna fisheries in the Indian Ocean are a vital food source for the region and help boost economies. Unfortunately, the fishing gear often used in this industry is extremely dangerous for whales and other marine mammals, which can get entangled and trapped in nets

Estimates indicate that more than 300,000 cetaceans—a family of marine mammals that includes whales, dolphins, and porpoises—die from entanglement in fishing gear each year, making this the single largest cause of mortality for them. Between 1950 and 2018, the use of pelagic drift gillnets—a type of fishing net suspended underwater that drifts with the current—targeting tuna and related species in the Indian Ocean likely resulted in over 4 million cetacean deaths, with annual fatalities reaching approximately 100,000 between 2004 and 2006 at their peak.

"While various factors contribute to cetacean mortality, such as direct harvesting and habitat degradation, incidental capture in tuna drift gillnets is particularly concerning and likely considerable," said Umair Shahid, WWF's Indian Ocean tuna manager. Shahid works closely with the Indian Ocean Tuna Commission, an intergovernmental organization responsible for managing tuna and tuna-like species in the Indian Ocean, and its member states to improve fisheries.

The Indian Ocean, a crossroads of global shipping traffic, is subject to intense fishing related to the growing number of people in the region, the importance of the fishing grounds to food security, and the availability of high-value species such as tuna. WWF and other partners are working to prevent the setting of nets around whales and other cetaceans and improve the reporting of when these mammals become entangled.

The Indian Ocean is home to numerous species of cetaceans, including many species of whales.

Humpback whales are found throughout the Indian Ocean, including an endangered sub-population in the Arabian Sea with a unique migratory pattern. There are also blue, sperm, fin, sei, and minke whales, and small cetaceans. In winter and springtime, critically endangered Antarctic blue whales are found in the tropical and subtropical Indian Ocean, and a smaller subspecies, pygmy blue whales, are present year-round.

Improving data reporting to protect whales and other marine mammals

Fishing fleets, particularly those using drift or fixed gillnets—a type of fishing gear often associated with humpback whale entanglements—are expanding throughout the central, western, and northern Indian Ocean. Gillnets are attractive to fishers because they are relatively inexpensive and do not require sophisticated equipment or bait. They pose a significant threat to cetaceans due to their unselective nature, capturing any large-bodied marine life that swims into the net. They are recognized as one of the most dangerous fishing gears for cetaceans. The use of large-scale driftnets is banned in the region.

"No other ocean basin has as much gillnet fishing as the Indian Ocean region," said Brianna Elliot, a specialist focusing on the impacts of international fisheries on marine megafauna populations with a regional focus on the western Indian Ocean at Duke University. Improving data reporting for gillnets and bycatch is vital to better understand and then reduce gillnet fishing.

A gillnet partially pulled out of the ocean

After a decade-long struggle, WWF and partners succeeded in amending a conservation and management measure on cetaceans regulated by the Indian Ocean Tuna Commission. The measure, aimed at reducing cetacean bycatch and addressing a lack of comprehensive data on cetacean interactions with tuna fisheries, now includes steps to prevent intentional net setting around cetaceans and requires reporting of cetacean captures or entanglements in tuna fishing operations.

"This is a vital first step. However, even though this is a strong regulation, it does not address increasing pressures from fishing and other human-led activities, or climate change, all of which present additional challenges that regulators must navigate to be effective," Shahid said. Furthermore, this resolution does not apply to small-scale fishing operations where many interactions with cetaceans occur."

Bycatch in fishing gear remains the leading driver of extinction risk for the world's whales, dolphins, and porpoises. The research conducted by Duke University and WWF is providing important insights into the size and dynamics of fishing fleets in the Indian Ocean, where large numbers of whales and dolphins are killed in tuna drift nets each year. We hope that we can translate this work to other areas and support new trials of methods designed to reduce the number of whales and dolphins killed in these fisheries.

"It's a complicated situation given the prevalence of gillnet fishing and reliance on this fishing method throughout the region for livelihoods," Elliot said. "Fortunately, there are a growing number of research groups and consortiums in the region that are producing excellent work and conservation efforts on this topic, and there are promising mitigation techniques that have demonstrated success at maintaining target catch while reducing cetacean bycatch."

Harmonizing this information across the region and providing incentives for using bycatch mitigation measures is vital. Then, importantly, presenting this science with collaborators with the Indian Ocean Tuna Commission to get more expertise at the commission's negotiations and improve management measures to reflect the latest science is key towards more data reporting and monitoring of gillnets.