March 22, 2018 — The future of the North Atlantic right whale is looking more and more bleak, and with their fate inextricably tied to the lobster and crab fishing grounds off the coast of Northern New England and Eastern Canada, pressure is mounting on the fisheries and their regulators to take more drastic action.
No right whale calves have been spotted so far this year – the latest in a string of bad news for the species, which lost 17 members in 2017. That total represented about four percent of its remaining population, and was around six times the normal mortality of the whales. An eighteenth dead whale was found entangled in fishing gear off the coast of Virginia in January. Gear entanglement, followed by blunt force trauma caused by collisions with ships, have been identified as the main causes of these deaths.
Philip Hamilton, a research scientist at the Anderson Cabot Center for Ocean Life at the New England Aquarium, who studies the mammals, said there’s slim hope remaining that researchers have missed spotting any new calves.
“The calving season isn’t considered completely over – the folks who are doing the surveys on the calving grounds off of Florida and Georgia will be going for another month, but we’ve never gone this long and not found a calf,” Hamilton said. “And there are only a few whales that have not been seen, so we’re not particularly optimistic that a calf will be seen down there.”
With only an estimated 100 breeding females left in the entire North Atlantic right whale population, scientists are closely monitoring the changing reproductive cycle of the whales.
“We have had drops in reproduction in the past. We had a dip in the early 1990s and then a pretty dramatic downturn in the late 1990s that culminated with just a single right whale calf born in 2000. So we have seen this before, but we’ve never seen it in conjunction with such extremely high mortality,” Hamilton said.
In addition to the premature deaths and low birth rate, the right whale species faces the new and additional challenge of a lengthier gestation period. According to Hamilton, their inter-birth interval has been increasing over the last five or six years, going from the standard of three to four years to 6.6 years in 2016, and jumping to an average of 10.2 years in 2017.
“There is a lot going on for them. We do know that females will forego reproduction if they aren’t in adequate body condition, meaning they have to have substantial fat reserves to support a calf. They end up losing up to a third of their body weight nursing a calf, so they have be able to handle that,” Hamilton said. “And there are a couple of factors which may be impacting female body condition. One would be food availability.”
The whales have been shifting where they feed in recent years and largely not going to some of their standard, historically productive feeding grounds like the Bay of Fundy and Roseway Basin and Great South channel east of Cape Cod. Instead, last year many ended up in Canada’s Gulf of St. Lawrence, where they are in much greater danger of entanglement with fishing gear, Hamilton said.
Read the full story at Seafood Source