Inbreeding seems to be causing more fetal deaths for North Atlantic right whales: study

A new study by a Halifax-based scientist is examining the critically-endangered North Atlantic right whale population and the challenges the species faces to grow its numbers.

Scientist and PhD candidate Carla Crossman and a research team at Saint Mary's University, along with other researchers across North America, have closely examined how inbreeding might be impacting the population and the reproduction of the whale.

"What we did find is that all of the calves in the population had more genetic diversity than we would have expected and genetic diversity is really important, so this is a good finding," said Crossman. "But what it means, too, is that the calves that don't have this genetic diversity aren't showing up, so we are likely losing a lot of calves due to inbreeding."

Published in the Royal Society Open Science Journal, the study suggests inbreeding is causing certain fetal losses in the population and could explain why so few calves are being born.

"We already know that we are not seeing as many calves as we would like to and this kind of findings that we had are really backed up by some other studies," said Crossman. "When we put that all together, we think we are seeing an increase of fetal loss due to inbreeding in the population."

The U.S. National Oceanic and Atmospheric Administration estimates there are fewer than 70 reproductively active females alive.

"Is she losing a calf right away but can get pregnant right away, or is she investing a year's worth of energy growing a calf, that is ultimately going to be lost?" questions Crossman.

Saint Mary’s University PhD candidate Carla Crossman analyzes a sample in the lab. (Courtesy: Tim Frasier)Understanding reproduction rates helps scientists better understand and predict population growth, says Crossman.

Human threats like vessel strikes and entanglement in fishing gear continue to put pressure on the species, hampering its population.

Dropcloth, a North Atlantic right whale, is pictured. (Courtesy: DFO Science Aerial Survey Team)

Fisheries and Oceans Canada (DFO) confirmed an adult male whale known as "Dropcloth" was recently spotted entangled in fishing gear among a group of right whales east of Miscou Island in New Brunswick.

The department doesn't know where the fishing gear came from and is monitoring to see if there's a chance crews can try to disentangle the whale.