Right whale survival may be dependent on snow crab fishery's flexibility
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 18 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.
“Ten years ago, right whales would be found in large numbers in the Bay of Fundy during the summer, and luckily their occurrence there was exact opposite of the lobster season. So even though there weren’t any regulations in Canada about fishing gear and whales, it ended up being a fairly safe place for them,” he said. “Now that they’re going up the Gulf St. Lawrence, their presence there overlaps exactly with snow crab season. Last year we had close to 100 whales in among a ridiculous amount of gear.”
Last year, two of the whales that died in the Gulf of St. Lawrence were females that were just on the cusp of giving birth. One was 10 years old and the other was 13, and neither had calved yet, Hamilton said. And two other whales that died last year were long-term calving females “known to be really good calvers,” he said.
Entanglements are not only causing very high levels of mortality, but they also have sub-lethal impacts, Hamilton said.
“We’ve recently shown that females that have serious injuries from past entanglements are reproducing much slower, if at all compared to females that have never been entangled or just have minor injuries from past entanglements,” he said. “So those two things may be influencing the fewer calves and longer inter-birth intervals.”
Entanglements are growing more serious because rope strength has increased, which causes greater injury and prevents whales from freeing themselves so they drown, Hamilton said. Finding a solution or solutions to the entanglement issue, and getting shipping traffic in areas where right whales are present to slow down, are the two keys in quickly reducing the mortality rates of the right whale and ensuring the survival of the species, Hamilton said.
Robert Haché, director general of the Acadian Crabbers Association, acknowledged in an interview with the CBC that Canada’s snow crab fishery has to find a solution to the risks it may pose to whales. The fishery is poised to reopen in about a month, depending on the weather.
The snow crab fishery in the southern Gulf of St. Lawrence is worth about CAD 129 million (USD 100 million, EUR 81 million) annually, but that value is in some jeopardy after the Marine Stewardship Council issued a temporary suspension of the fishery’s sustainability certification on Tuesday, 20 March, citing the fishery’s negative impact on the North Atlantic right whale population.
"In order for this fishery to regain use of its certificate ... it must establish and present to the independent certifier evidence that it's no longer causing harm to the population of right whales,” MSC Canada Program Director Jay Lugar said.
Despite the significant blow dealt to the North Atlantic right whale population in 2017, the species can still rebound, Hamilton said. In 2002, 39 calves were born only a year after there was just one birth.
“Our record low was followed by a record high,” he said.
That bump in calves was the result of an increase in the inter-birth interval in the late 1990s, which resulted in a large group of females. That doesn’t yet seem to be the case today, but right whales can live as long as humans, if not longer, Hamilton said, and that gives him hope that the stock can make it through difficult times to repopulate in the future.
“We should be expecting a fair number of new calving females to be coming of age now and not only coming of age, but reproducing, and we’re just not seeing that,” he said. “[But] I think the thing that is important for all of us to remember as we think about the situation is that they’ve had drops in reproduction in the past and have recovered from that. And they’re a very long-lived species.”