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Scientists from the NOAA Fisheries Service approach a young North Atlantic right whale to unravel it. New research shows that whales severely entangled in ropes and fishing gear are stunted and body length has been decreasing since 1981. NOAA News Archive 011811 hide caption
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Scientists from the NOAA Fisheries Service approach a young North Atlantic right whale to unravel it. New research shows that whales severely entangled in ropes and fishing gear are stunted and body length has been declining since 1981.
NOAA News Archive 011811
North Atlantic right whales are now getting smaller than they were 40 years ago, and new research suggests that one of the main causes is the damage human activity inflicts on critically endangered mammals.
The results, published today in the journal Current Biology, reveal that once an adult, a North Atlantic right whale born today should be about a meter shorter than a whale born in 1980. Currently, Adult members of the species average 13 to 14 meters in length (43 to 46 feet).
“The first idea we got came from the people collecting the data in the field, where, as the story goes, they saw what appeared to be a very young whale, a calf, or maybe a or two years old, ”said Joshua Stewart, postdoctoral researcher in the Division of Marine Mammals and Turtles of the National Oceanic and Atmospheric Administration (NOAA) and lead author of the new study. ‘were actually 5 or 10 year old whales that were smaller than a typical 2 year old. “
Researchers used high-resolution aerial photographs to track the size and body condition over time of 129 right whales. There are currently only about 366 North Atlantic right whales, compared to 481 in 2011, the record for population in recent years. Their numbers were much higher before commercial whaling brought them to the brink of extinction in the early 1890s. The high fat content and buoyancy of mammals after death led to their name: whalers called them the “Righteous whales” to kill.
A photographic illustration shows how much shorter a North Atlantic right whale born in recent years would be than a whale born years earlier. In each image, the outline shows how long researchers expected each whale to be born in 1981. “It’s just amazing,” said Joshua Stewart, lead author of the article. Madeline Wukusick hide the legend
toggle caption Madeline Wukusick
The research, with contributions from scientists at the New England Aquarium, the Woods Hole Oceanographic Institution and Oregon State University, indicated that one of the main reasons for the recent stunting of animals is entanglement in ropes and fishing gear.
North Atlantic right whales typically migrate along the east coast from Florida to Canada. In recent years, more than half of the population has been found from late winter to early spring off the coast of Cape Cod, where they navigate a deadly maze of ropes and lobster gear. .
Entanglements in equipment can lead to fatal infections, starvation or drowning. But even when they don’t kill whales, they can cause long-term damage, the researchers found. When mammals get caught up in human detritus and end up dragging it around, it forces them to expend more energy fighting for survival, instead of growing or repopulating their declining species.
“You can imagine that if you had a sandbag attached to you and you had to go about your day-to-day business, you would burn a lot of extra energy just by dragging that sandbag,” said Stewart.
A North Atlantic right whale in Cape Cod Bay. The callus patterns on each whale’s head are unique and allow identification, as well as tracking of impacts such as entanglements and vessel strikes, breeding history and age of individual whales. John Durban / NOAA and Holly Fearnbach / SR3, authorized by NMFS research permit # 17355 Hide caption
toggle caption John Durban / NOAA and Holly Fearnbach / SR3, authorized by NMFS research permit # 17355
Not only does entanglement help reduce an individual whale’s body size, but female North Atlantic right whales entangled during lactation produce smaller calves. This threatens the repopulation of a species with so few remaining members.
“This is a discovery that adds to the dark history of the right whale,” said Charles “Stormy” Mayo, director of the North Atlantic right whale ecology program at the Center for Coastal Studies in Provincetown. , MA, who did not contribute to the new research. “This is extremely important work because it not only demonstrates what we have always known, that entanglement causes death. But in this case, it goes beyond and confirms what some authors have long suspected. “
The stunted growth of whales coincides with an increasing rate of entanglements. A 2012 New England Aquarium study found that over 80 percent of right whales have been entangled at least once in their lifetime and 60 percent have been entangled more than twice.
“We know of other species of whales, including very closely related southern right whales, that in the case of mothers, when you give birth, if you are smaller and leaner, then your calf is also likely to be smaller. and leaner. ”said Stewart. “Especially as a calf, you have to grow very quickly in those early years, so you might have less chance of survival if you’re shorter.”
A North Atlantic right whale that a team of state and federal biologists helped unravel. Since 2017, 46 individual right whales have been found dead or seriously injured. This represents more than 10% of the population, according to NOAA. NOAA News Archive 123110 Hide caption
toggle caption NOAA News Archive 123110
A North Atlantic right whale that a team of state and federal biologists helped unravel. Since 2017, 46 individual right whales have been found dead or seriously injured. This represents more than 10% of the population, according to NOAA.
NOAA News Archive 123110
He added: “We also believe that if you are smaller you cannot accumulate as much energy as a longer whale. Their gas tank is smaller, which means if you run out of a lot of it reserve. when you are breastfeeding, say, a calf … you may have to wait longer between pregnancies. ”
Researchers recognize that tangles don’t explain all of the reduced growth. Other factors could be climate change, ship collisions and noise, as well as the changing availability of tiny crustaceans called copepods, their main source of food.
Researchers are now trying to establish whether other species of large whales and less studied marine mammals are suffering from a similar decline in their growth.
In response, environmentalists say fisheries managers need to better regulate crab and lobster fishing, whose vertical lines to traps on the seabed are believed to be the main culprit behind entanglements. One potential answer is a larger investment in the development and testing of cordless fishing technology.
Representatives of the lobster industry say they have been unfairly blamed for the entanglements and insist more research is needed to determine the source of the gear found coiled around these whales before new regulations can bring them to light. pushes into bankruptcy.
Researchers, however, say there is no time to wait.
“We’re in a very deep hole with right whales,” Mayo said. “Truly, the species cannot tolerate any further impact or its future is truly sealed.”
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