Right whale recovery in North Atlantic stalls

A new study shows right whales in the North Atlantic are having fewer calves at the same time as lethal entanglements increase.

More offshore fishing, heavier fishing gear, and more whale movement linked with decline

This North Atlantic right whale was freed from fishing lines in the Bay of Fundy near Campobello Island. (International Fund for Animal Welfare)

A new study shows the North Atlantic Right Whale population is having fewer calves at the same time as more whales are dying from fishing gear entanglements.

The chronically endangered species is "not yet a conservation success story," concluded the report, published last month in Frontiers of Marine Science.

Researchers found previous increases in the number of right whales have been offset by declining birth rates and more whales getting lethally tangled in fishing gear.

Hunted nearly to extinction

Researchers say many whales are moving from the Bay of Fundy into Cape Cod Bay and the Gulf of Saint Lawrence. (Annabel Beichman)
Scott Kraus, the study's lead author and vice president of research at the New England Aquarium, explains the right whale was, for centuries, seen as "the right whale to kill, because it floated after it was dead."

As a result, the North Atlantic right whale neared extinction in the mid-1930s. Killing the whales was made illegal in 1935.

"After we stopped killing them, the recovery "remained steady until 2010," said Kraus.

"They continued to recover right through 2010, [by which time] we saw the population grow to 500 animals," said Kraus.

The right whales are having fewer calves and dying at higher rates through the North Atlantic. Scott Kraus is VP of Research at the New England Aquarium. 6:35

More entanglements

Yet the expansion of offshore fishing activities, advent of heavier offshore fishing gear and increased movement of existing whale populations have meant deadlier consequences for whales that get caught in fishing gear.

In fact, says Kraus, "over 83 per cent of all right whales in the North Atlantic have been entangled in fishing gear at one time."

"As they encounter stronger ropes and heavier gear, the damage to the animals is more severe and lasts longer," said Kraus. "It's like if you break a leg, it takes you weeks or months to recover."

"Even if they're able to break free the consequences last for some time in terms of their health and their ability to reproduce."

Fewer baby whales

Over 83% of all right whales in the North Atlantic have been entangled in fishing gear at one time, according to study lead author Scott Kraus. (Penny Graham)
Kraus said the decreased number of right whale babies could relate to the fact that many are moving "into Cape Cod Bay in the spring, and the Gulf of St Lawrence in the summer."

The shift has been "surprising" to researchers, he says, but could be linked with food supplies moving in response to "very high warming temperatures in the the Gulf of Maine."

"As they're looking for food they start moving into more areas. The more time you spend looking around, the less time you spend eating.

"And when you don't get as fat, you can't have as many babies."

Other theories have to do with long-term damage caused by fishing gear entanglements and generational diseases.

"There's some change in the ecosystem that's not clear to us," says Kraus.

Changes in fishing gear needed

Making it easier for the animals to escape if they become entangled in fishing gear could be one way to protect the whales, according to researchers.

"We don't have control over some of the natural shifts in distribution, but we do have control over the human causes of injury and mortality," says Kraus.

"Fishermen don't want to kill or entangle whales, and the whales certainly don't want to get entangled," Kraus says.

"We're trying to reduce the probability of entanglement, and if a whale does get entangled, [making it so that] it can break free and get out."

with files from Information Morning Saint John