When an endangered female North Atlantic right-wing whale lasts for months or even years, separating from flying fishing nets, there is not much energy to mate and care for calves.
Facing such waste, together with ship collisions and other forms of human consequence, seriously halted the recovery of magnificent marine mammals long after the explosive harpoons and factory ships were almost wiped out, according to a study published on Wednesday.
In tens of thousands, the population of the northern whale, which has been floating for 450 days, has slowly climbed since 1990, but it began to fall again in 2010.
If Canadian and American waters that swam in that quarter of the century were clean and unprotected by human traffic, "species numbers would be nearly double as much as they are now, and the current urgency would not be so harsh," said scientist Peter Corkeron of the NEAA Scientific the Fisheries Center in Massachusetts.
Moreover, twice as many female whales will be: "The general inclination of the trajectory to recover comes from the mortality of women," they added.
From 1970 to 2009, 80 percent of the 122 known North Atlantic deaths of right whales caused human objects or activities.
This species has not been found for more than half a century.
However, over the number of killed whales, the question was whether the populations of species could be reduced in a more subtle way by humans.
To find out, Corkeron compared gender processes with the southern right whale, and the sister species on the southern hemisphere – estimated at about 15,000 – which is in much better shape and far less exposed to harmful human emanations.
The data gathered over the last three decades have allowed the number of new calves to be born in different sub-populations on both sexes.
North and South Whales have long thought they were one species until genetic analysis showed otherwise.
As was suspected, three groups of southern whales – the coasts of eastern South America, southern Africa and southwestern Australia – produced offspring twice as high as their northern generations.
Further evidence that the North Atlantic environment had taken into account was the poor health of females and their calves, the study showed.
"This female white whale gives up reproduction in response to poor conditions in the body is well established," the authors said.
What caused lacerations, reduced body weight, and apparent unwillingness to mating?
The most likely culprit is "spiritual networks," fishing nets that are often made of synthetic fibers, for how long, study concludes.
More than 80 percent of all North Atlantic right-wing whales are known to have been frightened into abandoned network at least once, and more than half have been there twice or more.
"Entanglements can last from months to years, and recovery can take the same," wrote the authors Roial Société Open Science.
For the southern whales, the problem does not exist.
Once they were numbered in hundreds of thousands, while the movement of real whales toward the coastal regions took place, and it was easier and desirable to rob in the 20th century.
This species can grow to 20 meters (65 feet) and weighs 100 tons, more than a fully loaded commercial jet.
They are also obedient and full of mantles from which a whale oil is made.
The endangered whip whale fell on the Belgian beach
The recovery of North Atlantic right whales, Eubalaen glacialis, was limited by mortality caused by humans, Roial Société Open Science, rsos.roialsocietipublishing.or … /10.1098/rsos.180892