Right whales born today are shorter by approximately one meter as compared to their counterparts born in the 1980s, according to new research published in the journal Current Biology. The study has established that whales born today are shorter and smaller in body size due to the impact of human activities.
Currently, a full-grown right whale measures between 13 and 14 meters in length on average. This is quite short as compared to the traditional length of these whales. Joshua Stewart, a postdoctoral researcher with the National Oceanic and Atmospheric Administration’s (NOAA) Marine Mammal and Turtle Division and lead author of the study, said that the findings were first made from an accidental discovery.
“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,” Stewart told NPR. “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.”
In their research, the scientists used high-resolution aerial photos to track the sizes and overall body conditions of 129 right whales. The team of researchers, which included participants from New England Aquarium, Oregon State University and Woods Hole Oceanographic Institution, found that the endangered whales had reduced in size over time.
According to the study, right whales experience stunted growth due to entanglement in ropes and fishing gear. The Northern Atlantic right whales have been increasingly found trapped in fishing gear in their seasonal migration between Florida and Canada. There are only 366 Northern Atlantic right wales in existence. Entanglements in the gear can lead to fatal infections, starvation or drowning. If the entanglements don’t kill the whales, they can still cause long-term damage.
“You can imagine if you had a sandbag tied to you and you had to go about your daily business, you’d be burning a lot of extra energy just dragging that sandbag around,” Stewart said.
Stewart also noted that if the size of mother whales is affected, chances are that they will give birth to smaller babies. “We know from other species of whales, including really closely related southern right whales, that in the case of moms, when you’re giving birth, if you’re smaller and skinnier, then your calf is also likely to be smaller and skinnier.”
Entanglements aren’t the only culprit. The researchers noted that other possible causes could include collisions with boats, food scarcity and climate change.
Image via NOAA