SYDNEY, March 13 (Xinhua) -- New research led by Australian marine scientists has shed light on the severe impact of fishing gear entanglements on the survival of North Atlantic right whales, a species listed as critically endangered by the International Union for Conservation of Nature.

In their study published in the Proceedings of the Royal Society B journal, the researchers analyzed 40 years of data on 199 female right whales together with known fishing-gear entanglements to calculate the impact of these encounters on whale reproduction.

Modeling of whale-sightings data suggested that when female right whales get tangled in ropes from lobster and crab pots, they are less likely to calve, which potentially leads to extinction for this species.

"Poor calving is one of the main factors behind the decline of North Atlantic right whales and, until now, the reason for these whales' failure to calve wasn't clear," said Joshua Reed, lead author of the study and doctoral candidate from Macquarie University.

"This study makes it clear that all types of entanglement in fishing gear impact females' ability to calve, helping address one of the big, outstanding questions for saving North Atlantic right whales," Reed noted in a statement on Wednesday.

Currently, fewer than 350 North Atlantic right whales remain alive worldwide, making them the second-most endangered great whale species. Fishing gear entanglement is considered a major threat to their survival.

Prior work showed that 89 percent of females experienced at least one entanglement event during their lifetime, with almost two-thirds of them enduring two or more.

According to the new study, pre-breeders who endured minor or severe entanglements in a particular year had a lower chance of transitioning into the breeding population, compared to those not entangled or who had moderate entanglements.

Surprisingly, those with minor entanglements showed the lowest probabilities, with individuals being on average 47 percent less likely to breed in contrast to the non-entangled females.

"This study makes clear that using value-laden terms such as 'minor', 'moderate' and 'severe' to describe the relative severity of scars from entanglements is inappropriate," said co-author Rob Harcourt, honorary professor from Macquarie University's School of Natural Sciences.

"These terms lead to an unconscious assumption that 'minor' injuries aren't important, when in fact they are," he added.

The research team delivered a conclusion that management actions are needed to address the lethal and sub-lethal impacts of all entanglements, regardless of severity classification. Enditem

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