Many fish, marine mammals and seabirds that inhabit the world’s oceans are critically endangered, but few are as close to the brink as the North Atlantic right whale (Eubalaena glacialis). Only about 411 of these whales exist today, and at their current rate of decline, they could become extinct within our lifetimes.
From 1980 through about 2010, conservation efforts focused mainly on protecting whales from being struck by ships. Federal regulations helped reduce vessel collisions and supported a slight rebound in right whale numbers.
But at the same time, growing numbers of right whales died after becoming entangled in lobster and crab fishing gear. This may have happened because fishing ropes became stronger, and both whales and fishermen shifted their ranges so that areas of overlap increased. Entanglement has caused 80% of diagnosed mortalities since 2010, and the population has taken a significant downward turn.
This comes after a millennium of whaling that decimated the right whale population, reducing it from perhaps between 10,000 to 20,000 to a few hundred animals today. And entanglement deaths are much more inhumane than harpoons. A whaler’s explosive harpoon kills quickly, compared to months of drawn-out pain and debilitation caused by seemingly harmless fishing lines. We believe these deaths can be prevented by working with the trap fishing industries to adopt ropeless fishing gear – but North Atlantic right whales are running out of time.
Whalers pursued right whales for centuries because this species swam relatively slowly and floated when dead, so it was easier to kill and retrieve than other whales. By the mid-20th century, scientists assumed they had been hunted to extinction. But in 1980, researchers from the New England Aquarium who were studying marine mammal distribution in the Bay of Fundy off eastern Canada were stunned when they sighted 26 right whales.
Conservation efforts led to the enactment of regulations that required commercial ships to slow down in zones along the U.S. Atlantic coast where they were highly likely to encounter whales, reducing boat strikes. But this victory has been offset by rising numbers of entanglements.
(c) Nick Hawkins
Adult right whales can produce up to an estimated 8,000 pounds of force with a single stroke of their flukes. When they become tangled in fishing gear, they often break it and swim off trailing ropes and sometimes crab or lobster traps.
Lines and gear can wrap around a whale’s body, flukes, flippers and mouth. They impede swimming and feeding, and cause chronic infection, emaciation and damage to blubber, muscle and bone. Ultimately these injuries weaken the animal until it dies, which can take months to years.
Michael Moore, NMFS Permit 932-1905-00/MA-009526, CC BY-ND
One of us, Michael Moore, is trained as a veterinarian and has examined many entangled dead whales. Moore has seen fishing rope embedded inches deep into a whale’s lip, and a juvenile whale whose spine had been deformed by the strain of dragging fishing gear. Other animals had flippers nearly severed by swimming wrapped in inexorably constricting ropes. Entanglement injuries to right whales are the worst animal trauma Moore has seen in his career.
Even if whales are able to wriggle free and live, the extreme stress and energy demands of entanglement, along with inadequate nutrition, are thought to be preventing females from getting pregnant and contributing to record low calving rates in recent years.
Solutions for whales and fishermen
The greatest entanglement risk is from ropes that lobster and crab fishermen use to attach buoys to traps they set on the ocean floor. Humpback and minke whales and leatherback sea turtles, all of which are federally protected, also become entangled.