Fishing gear confirmed as major cause of right whale deaths

A major study looking into the deaths of North Atlantic right whales has found that entanglement in fishing gear has become a leading cause of mortality.

Right whales are critically endangered, with only about 360 remaining in the world's oceans.

The study by the Woods Hole Oceanographic Institute in Massachusetts found that from 1970 to 2009, ship collisions were the leading cause of mortality in the whales. However, from 2010 to 2015, a large majority of deaths were caused by fishing gear.

Michael Moore, a co-author of the study, said the goal was not to point fingers.

"We're interested in how to bridge the gap between the needs of the fishing industry and the North Atlantic right whale species, as much as both have a right to survive and thrive," Moore told Island Morning's host Laura Chapin.

Right whales are prone to entanglement in fishing gear because they often swim close to shore. Traps on the ocean floor are connected by lines to buoys floating on the surface that mark their position.

When the whales swim through an area being fished, they can get caught in the lines. The ropes can cause scarring, and dragging the buoys and traps will sap the whale's energy and hinderits ability to feed.

Even if the whale survives, that can lead to females not being fit enough to become pregnant.

A study that examined all available photographs of North Atlantic right whales taken from 1980 to 2009 found that 83 per cent showed scars caused by ropes or nets, and 59 per cent had been entangled more than once.

New feeding areas

The whales became an issue in the Gulf of St. Lawrence in 2017, when whales started to arrive to feed in the southern gulf, rather than in the Bay of Fundy where they had traditionally been spotted.

Canadian regulators responded with speed limits for ships, whale-spotting patrols, and temporary closures of fisheries when whales were seen in an area.

"It's very complicated and very challenging," Moore said of the response.

"Despite the challenges they've had, especially in 2017 and 2019, I think Canadian federal, provincial [governments] and industry has been really, really responsive and trying very, very hard to make ends meet for both the right whales and the fisheries and the shipping industry."

How to save the whales

The report went on to review potential solutions, including traps designed without lines that run up to the surface.

In these systems, the traps and the lines lie on the bottom. The buoys are either inflatable or weighed down. To retrieve them, fishermen signal them to either inflate the buoy or release the weight.

Moore acknowledges that these systems are more expensive.

But fishermen are already paying the cost of having to occasionally haul their traps up when right whales are known to be passing.

The new systems are currently being tested in both Canadian and U.S. waters.

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