Worldwide Bycatch of Cetaceans: An Evaluation of the Most Significant Threats to Cetaceans, Affected Species and Geographic Areas of High Risk, and Recommended Actions from Various Independent Institutions

Humans have exploited cetaceans (whales, dolphins, and porpoises) since primitive whaling activities began in Japan and Scandinavia many centuries ago. The U.S. Ocean Commission in 2005 judged incidental catch in fisheries the “biggest threat to marine mammals worldwide . . .[killing] hundreds of thousands of them each year.” Fishing gear, especially gillnets, indiscriminately catches an undetermined number of marine species, including dolphins and porpoises. Still, progress on quantifying the scale of this mortality, identifying the magnitude of this threat, and mitigating or reducing the mortality has been slow, sporadic, and limited to a few specific fisheries or circumstances.