Study finds that right whales are getting smaller



BAR HARBOR — Entanglements in fishing gear and other factors are stunting the growth of North Atlantic right whales, according to new findings published in Current Biology.

The new research showed that even when entanglements do not lead directly to the death of North Atlantic right whales, they can have lasting effects on the dwindling population of the endangered species.

A right whale born today is expected to reach a full-grown length that is about 3 feet shorter than one born in 1980.

“We normally see these major life-history impacts in heavily exploited commercial species,” Joshua Stewart, a postdoctoral researcher at NOAA Fisheries’ Southwest Fisheries Science Center and lead author of the new research, said in a statement. “While the average body size decline is striking, there are some truly extreme examples where five- and ten-year-old whales are shorter than a typical one or two year old.”

The stunted growth of the whales comes with an increasing rate of life-threatening entanglements, leaving them with less energy to devote toward growth. The scientists suggest that the ongoing stress of entanglements may reduce the reproduction rates of females and possibly affect the survival of calves and adults.

Other factors that could contribute to the declining health include vessel noise and shifting availability of the tiny copepods that are their primary prey.

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