Already endangered, North Atlantic right whales face an even more uncertain future following the Southeast’s second-worst calving season since surveys began in the 1980s.
Researchers with Georgia DNR, the Florida Fish and Wildlife Conservation Commission, NOAA and Sea to Shore Alliance saw only seven right whales this winter off Georgia, north Florida and South Carolina, traditionally calving central for this species that literally grows as big as a bus. Only three of those whales were calves (a fourth calf was seen in Cape Cod Bay this month).
Clay George, DNR’s lead right whale scientist, said the average number of calves reported in the region has dropped by half, from 24 calves annually 2001-2011 to 12 a year since 2012. This winter also registered a new low for the total number of whales documented — seven. Season totals topped 100 per year in the mid-2000s.
“Is this just the low point in a natural cycle, or are low calving numbers the new normal?” George said. “We just don’t know. All we can do is wait and see.”
Considering there are as few as 440 North Atlantic right whales left, long-term declines in calving could increase the risk of extinction. The number of calves, George said, “just isn’t keeping up with mortality.”
There is no strong evidence that right whales are simply having calves farther north on the Atlantic Seaboard. Also, female calving intervals have increased in recent years, suggesting the whales aren’t getting enough zooplankton on their feeding grounds off Canada and New England. Healthy moms should be calving every three or four years, George said.
“Now, moms are only calving every six to eight years.”
What is driving these big-picture changes isn’t clear. What is, however, is the importance of reducing the risk of ship strikes and entanglement in commercial fishing gear – both leading threats to right whales.
Long-lived species, like right whales, can tolerate periods of low reproduction, but only if adult survival rates remain high. Unfortunately, four right whale deaths have been confirmed in the past 12 months, three of which were caused by ship strikes or entanglement, according to the Center for Coastal Studies.
Another death was probably narrowly avoided this winter. One of the whales seen in the Southeast was an adult male dragging a 135-pound crab pot and 450 feet of fishing rope. Responders cut away the gear and the whale named Ruffian was later seen feeding in Cape Code Bay.
Ruffian is covered in scars from an entanglement a decade ago that left him badly hurt. Such encounters aren’t rare: More than 80 percent of right whales bear scars from commercial fishing gear entanglements.
The calving downturn could right itself. A three-year decline in the late 1990s ended with only one calf in 2000. Then came 31 calves in 2001, followed by a decade of strong calving and population growth.
This season’s fourth calf, documented in Cape Cod Bay, was a welcomed addition. Researchers are hoping for more – many more – next winter.