Almost a third of bowhead whales in the Sea of Okhotsk have been entangled in fishing gear

A joint expedition of WWF-Russia, the Severtsov Institute of Ecology and Evolution of the Russian Academy of Sciences and the Marine Mammal Council was held in the summer and autumn of 2021 in Wrangel Bay, as well as in the Nikolay and Ulbansky Bays of the Sea of Okhotsk. The main goal was to study the local population of the bowhead whale (its number is estimated at 300-400 individuals) and highlight the most relevant threats. 

Studies have shown that about 35 percent of the whales of the herd were entangled in ropes or fishing gear at least once in their lives – 50 of the 144 whales studied had specific scars – linear cuts, most often marked on the caudal peduncle, tale, pectoral front fins, and around the mouth. These individuals managed to free themselves from ropes or nets, but such entanglements can be very dangerous for whales – the ropes tightens as the animal moves. One of the whales studied by the expedition had lost its tail fluke this way. More than a third of the population of bowhead whales in the Sea of Okhotsk is affected by this threat.

“Of course, we knew that the bowhead whales suffer from entanglement in ropes and fishing gear more than other whales, but we had no idea that this problem would be so urgent for the Sea of Okhotsk population. In another population, which lives in the Bering and Chukchi Seas, “only” about 12% of whales have this type of scars – almost three times less than in the Sea of Okhotsk,” – said Boris Solovyov, WWF-Russia’ senior project manager for marine protected areas.

This tiny population is suffering due to climate change, killer whale attacks and rapidly developing economic activity in the region, including tourism in key summer whale habitats. Therefore, the detected traces of entanglements raise particular concerns.

“It is too early to draw conclusions about where and in what exactly whales get entangled and injured – these may be orders with crab traps, set seines, and poaching nets, and/or abandoned or lost fishing gear, ropes," – Boris Solovyov added. – “In order to find out the causes and decide what can be done to reduce the scale of this impact, we need to cooperate with fishermen and fisheries science. We hope for a productive dialogue and are confident that our colleagues understand the importance of the problem.”

More than 2,000 photos and videos of whales taken from drones were collected during the 2021 expedition. With their help, the researchers identified 114 individuals, most of which were met and documented for the database for the first time. This is about a third of the total number of the summer Shantar stock. Photos and parameters of newly-identified whales were entered into a database. This work has been kept for several years and repeated meetings with already identified animals allow one to understand the nature of the movements of whales and other features of their life cycle. Scientists recognize whales by their scars and by the peculiarities of skin pigmentation – almost every adult animal has unique markings.

This year WWF-Russia and the Severtsov Institute of Ecology and Evolution of the Russian Academy of Sciences plan to conduct a new expedition to the Sea of Okhotsk, which will allow them to continue studies of the local population of bowhead whales and to develop and implement measures for their conservation.

The WWF-Russia plans to raise funds for this expedition with the help of its supporters, as well as for the previous one. The national fundraising campaign was launched on the eve of the Day of Biological Diversity on WWF-Russia website. 

“Conservation of biological diversity is a continuous process. Nature cannot be put on pause. It is worth stopping pedaling on a bicycle – you will fall very soon. Effective environmental work is impossible without constant monitoring and collection of information," says Dmitry Gorshkov, Director of the WWF-Russia. – Talking about the Sea of Okhotsk population of bowhead whales – without a new expedition it will not be possible to develop and implement measures for their conservation, and some of the previous work and accumulated materials will become useless.” 

During the expedition, the distribution of fishing gear potentially dangerous for bowhead whales in the Shantar area and in the entire Sea of Okhotsk will be assessed. Possible sources of whale injury, types of gear used and areas of their distribution will be identified. An assessment of the danger of abandoned and lost fishing gear and ropes for whales will be given and appropriate recommendations will be prepared.