There are now believed to be fewer than 400 right whales, making them among the planet’s most endangered species. The main threat to their survival, scientists say: millions of lobster lines that stretch from New England up through Atlantic Canada, standard gear for North America’s most valuable fishery. Exacerbating that threat is climate change, which has sparked a collapse in the whale’s food supply in the warming waters of the Gulf of Maine, forcing them to search for food in areas where they had rarely been seen before. At the current rate of decline, scientists say the whales could go extinct within 20 years. Now, under pressure from lawsuits by environmental advocates to reduce right whale deaths, the federal government has been considering controversial regulations that pit the region’s politically powerful lobstermen against scientists and environmental advocates trying to save the whales.

Entangled chronicles the efforts to protect North Atlantic right whales from extinction, the impacts of those efforts on the lobster industry, and how the National Marine Fisheries Service has struggled to balance the vying interests.