A gruesome secret hides in the waters off the California coast: mile-long nets that sit in the ocean like invisible walls.
Fishermen use these drift gillnets to catch swordfish and thresher sharks, but Ashley Blacow, Pacific policy and communications manager for Oceana, said they also catch other creatures that either drown or are tossed overboard.
"They're a non-selective type of fishing gear that end up entangling many different species of marine life that travel through the open ocean like blue shark, striped marlin, dolphin, ocean sunfish, and even large whales," Blacow said.
There are cleaner, more responsible ways to fish, she said, especially in waters that are home to many endangered species. Oceana is working to have the National Marine Fisheries Service and the state of California follow the lead of Washington and Oregon and ban the use of the nets.
Blacow called it inexcusable for the National Marine Fisheries Service and the state of California to allow the use of nets that capture everything in their path. For every five swordfish caught in 2011, she said, one marine mammal was killed and six fish -- including sharks and tuna -- were tossed overboard, dead or dying.
"In 2011, the National Marine Fisheries Service estimates that drift gillnets took 16 endangered sperm whales," she said, "which is really amazing if you think about the diverse array of marine life and even just the vast size of marine life that are caught in these large nets."
Fishermen like the large nets because they're effective. However, Blacow said swordfish individually caught with harpoons can be sold for double the price per pound.
Oceana successfully blocked an expansion of drift gillnet fishing into protected areas off California this year.