June 3, 202111:06 AM ET
Scientists from NOAA Fisheries Service approach a young North Atlantic right whale in order to disentangle it. New research shows whales with severe entanglements in rope and fishing gear are experiencing stunted growth, and body lengths have been decreasing since 1981.NOAA News Archive 011811
North Atlantic right whales now grow smaller than they did 40 years ago, and new research suggests a leading cause is the damage human activity inflicts on the critically endangered mammals.
The findings, published today in the journal Current Biology, reveal that when fully grown, a North Atlantic right whale born today would be expected to be about one meter shorter than a whale born in 1980. Currently, full-grown members of the species average 13 to 14 meters in length (43 to 46 feet).
“The first inkling that we had came from the folks who were collecting the data in the field, where, as the story goes, they saw what looked to be a really young whale, a calf, or maybe one- or two-year-old,” said Joshua Stewart, a postdoctoral researcher with the National Oceanic and Atmospheric Administration’s (NOAA) Marine Mammal and Turtle Division and lead author of the new study. “But it turns out that they were actually 5-year-old or 10-year-old whales that were smaller than a typical 2-year-old.”
The researchers used high-resolution aerial photographs to track size and body condition over time of 129 right whales. There are only about 366 North Atlantic right whales in existence now, compared to 481 in 2011, the known high for the population in recent years. Their numbers were much higher before commercial whaling brought them to the brink of extinction by the early 1890s. The mammals’ high fat content and buoyancy after death led to their name: whalers called them the “right whales” to kill.
A photo illustration demonstrates how much shorter a North Atlantic right whale born in recent years would be compared to one born years earlier. In each image, the outline shows how long researchers expected each whale to be had it been born in 1981. “It’s just astonishing,” said Joshua Stewart, lead author on the paper.Madeline Wukusick
The research, with contributions from scientists with the New England Aquarium, Woods Hole Oceanographic Institution, and Oregon State University, indicated that a prime reason for the animals’ recent stunted growth is entanglement in rope and fishing gear.