When marine mammals encounter fishermen, the ocean creatures are losing their lives at the rate of nearly 1,000 a day.
Scientists say that's how many whales, dolphins and porpoises drown every day after getting tangled up in fishing nets and other equipment.
This new study done by American and Scottish biologists seems to be the first global estimate of the problem.
Researchers say more than 300,000 marine mammals die unintentionally every year in fishermen's nets. This includes species ranging from 100-pound porpoises to the 120-ton blue whale. The study says this may pose the biggest immediate threat to these animals' survival - even more than ship collisions and pollution.
The report was released by World Wildlife Fund, a Washington-based advocacy group, as governments gather in Berlin for the 55th annual International Whaling Commission meeting.