A black rope had rubbed the whale\u2019s flesh raw and white, making it easier for marine mammal rescuers to see the months-old humpback entangled in fishing gear off Cape Cod, Massachusetts. Using a nine-meter pole tipped with a sharp hook, rescuers from the Center for Coastal Studies (CCS) cut away the tangled gear\u2014one of several similar rescue operations the team conducts each year.<\/p>\n
The vast majority of the team\u2019s rescue attempts are a success. But to Bob Lynch, CCS\u2019s rescue operations manager, their efforts are a band-aid fix. There are many whales they can\u2019t get to, he says. Beyond that, while disentanglement can save a whale, it can\u2019t save the species, says Lynch. \u201cWhat we\u2019re doing is not a solution to the problem whatsoever.\u201d Preventing whales from getting entangled in the first place will have a larger impact on their protection.<\/p>\n
Vessel strikes and entanglement in fishing gear are the leading causes of human-caused mortality for humpbacks and other baleen whales. Over the past several years, scientists and conservation managers around the world have tried all sorts of things to prevent entanglements, including testing ropeless gear<\/a>, increasing marine litter cleanup efforts<\/a>, and implementing seasonal closures of areas that whales frequent. But off the Massachusetts coast, research led by Tammy Silva, a marine ecologist at the Stellwagen Bank National Marine Sanctuary (SBNMS), hints at another way to find whales and hopefully prevent their entanglement. Key to the approach is the overlap of habitat use between humpback whales and one kind of seabird\u2014the brown-washed great shearwater.<\/p>\n North of Cape Cod Bay, in the choppy waters off the SBNMS, great shearwaters often gather in the hundreds. Through tracking studies, Silva and her colleagues have shown that a congregation of great shearwaters can signal that a pod of humpback whales is swimming below. Both species are preparing for an offshore feast\u2014the whales ascend from the deep to capture sand lance, a silver eel-like fish. Shearwaters lie in wait to pick from what the whales miss.<\/p>\n While it\u2019s possible to track whales directly using satellite tags, the approach can be expensive, and the tags have a short life span. Catching and tagging seabirds, says Dave Wiley, SBNMS\u2019s research coordinator, is also much easier than tagging a humpback whale.<\/p>\n Tracking shearwaters starts with getting birds in hand, Silva explains. Because great shearwaters spend the bulk of their lives on the open ocean, traveling to land only to breed, researchers have to capture them at sea. So, each year since 2012, the team has choreographed what Silva describes as an alien abduction.<\/p>\n Launching in a small inflatable boat from their mother ship, a 15-meter vessel in the Gulf of Maine, three or four team members set out after a raft of shearwaters. One team member tosses chopped mackerel and squid to lure birds in, while the others use long handheld nets to scoop the birds into the boat. Working quickly to minimize stress on the animals, they place each bird in a cat carrier to relax.<\/p>\n After they\u2019ve caught several birds, they head back to the mother ship. There, the scientists collect samples to gauge each bird\u2019s health and diet, and stitch a small solar-powered satellite tag to the skin between its wings.<\/p>\n