Right Whales: What is happening in 2019
The North Atlantic right whale is endangered, with an estimated population of only about 400 individuals. The main threats faced by this species are entanglements in fishing gear (ropes) and collisions with ships. Part of the North Atlantic right whale population has traditionally spent summers in the Bay of Fundy. Since 2017, the Bay of Fundy appears to be less heavily visited and a major increase in right whale sightings has been noted in the Gulf of St. Lawrence. In 2017, twelve right whale carcasses were found in the Gulf. Mitigation measures to lower the risks of entanglement and collisions were urgently implemented that summer. Measures were also applied in 2018; no carcasses were found that year. This year, speed reduction zones and mitigation measures have once again been put into place. Follow the latest right whale news here.
Interactive map of North Atlantic right whale sightings in Canadian waters: WhaleMap and On alert for whales
NOAA right whale sighting advisory system NOAA
Speed reduction measures for collision prevention: Transports Canada
Fishery management measures: Fisheries and Oceans Canada
Fishing closures for North Atlantic right whale protection: Fisheries and Oceans Canada
2017 mortality event: Whales Online
The situation in 2018: Whales Online
Key dates in 2019
June 4: Discovery of a right whale carcass, which was identified as Wolverine, a male born in 2010.
June 7: Necropsy of the right whale in Miscou, New Brunswick. Analyses failed to identify the exact cause of death.
June 20: Discovery of a second right whale carcass.
June 25: Necropsy of the right whale Punctuation in Chéticamp, Nova Scotia. Discovery of two new right whale carcasses, bringing the total to four.
June 26: Discovery of a fifth carcass on Anticosti Island, Quebec.
June 27: Discovery of a sixth carcass, that of Clipper, off the Gaspé Peninsula.
June 28: Necropsy of Comet in the town of Norway, Prince Edward Island.
June 29: Report of an entangled right whale northeast of Miscou Island, New Brunswick.
July 1: Necropsy of Clipper in Grand-Étang, Quebec. Preliminary results of the necropsy show that the mortality was caused by a collision.
July 4: Report of two other entangled right whales. One, unidentified, was off Gaspésie, Quebec, while the other, EG#4423, was east of Miscou Island, New Brunswick.
July 8: The government of Canada announced new mitigation measures to prevent entanglements and ship strikes.
July 12: An intervention occurred on right whale EG4423 to free it from its fishing gear. It was a partial success.
July 16: Right whales EG4423 and EG4440 are partially detangled after rescue attempts.
Snapshot of the six right whales
Special thanks goes out to the New England Aquarium’s Anderson Cabot Center for Ocean Life for the information contained in the North Atlantic right whale photo-ID catalogue. To read the complete portraits, click on the names of the whales.
Parent: Female #3123
Year of birth: 2010
Life events: Collision at age 5 with an engine propeller, which left this individual with three large scars. During the first five years of his life, Wolverine was seen entangled three times, with two of these entanglements considered minor and one moderate, according to the standards developed by the New England Aquarium.
Cause of death: necropsy results inconclusive to identify the cause(s) of mortality.
Sex: Sex: Female
Age: approx. 40 years
Calves: at least 8, two of whom also had calves of their own
Life events: Struck by ships at least two other times. Entangled at least five times.
Cause of death: trauma corresponding to the after-effects of a ship strike.
Year of birth: before 1989
Cause of death: trauma corresponding to the after-effects of a ship strike.
Identification: not known
Year of birth: before 2008
Cause of death: Due to the advanced state of decomposition, no necropsy will be performed. Sampling could be performed at sea. At the moment, no information on the cause of death.
Age: Born in 2003 (16 years old)
Parents: female Viola #2029 and male #1419
Life events: Entangled at least four times in fishing gear
Cause of death: unknown
Calves: 1, in 2016
Life events: Has experienced at least one other collision, during which much of her caudal fin was severed, hence her nickname “Clipper”. Also experienced two minor entanglements.
Cause of death: trauma corresponding to the after-effects of a ship strike
July 16 | Disentanglement efforts progress
Right whales EG4423 and EG4440 are now swimming a little lighter since shedding some of the rope that had been wrapped around their bodies. On July 16, the Campobello Whale Rescue Team, assisted by crews from Fisheries and Oceans Canada and the National Oceanic and Atmospheric Administration (NOAA), was able to resume its attempts to rescue two out of three entangled right whales. Weather conditions of the previous days were too dangerous to attempt such an operation.
During aerial surveillance flights, right whale EG4423 was spotted in the morning. She had already been partially disentangled on July 11. Despite the efforts made on July 16, it was not possible to completely remove the fishing gear in which she had become ensnared, though responders were able to detach some of the rope. The teams present likely reduced the load that this whale had been dragging with it since April 2019, when it was potentially observed in the United States.
As for EG4440, it was spotted in the late afternoon. Although it, too, could not be completely released from the fishing gear in which it is trapped, the rope caught from the jaw to the tail was able to be cut off.
Overflights will continue over the next few days to document the presence and activities of right whales in the Gulf of St. Lawrence. If entangled whales EG4440 and EG 4423 are spotted again, teams will observe how their predicaments have evolved following these disentanglement attempts. The teams have not yet relocated the third entangled whale.
No other entanglement incidents involving North Atlantic right whales have been observed since the discovery of these three whales.
July 12 | EG#4423 is partially disentangled
Good news! The right whale EG#4423 was partially disentangled yesterday. The ropes restricting the movements of his tail could be removed, but attempts to remove the additional gear had to be stopped at nightfall. EG#4423 has probably been entangled since April 2019, while it was still in US waters.
July 11 | Tougher Prevention Measures to Protect North Atlantic Right Whales
Speed restrictions applied to a larger fleet, increased aerial surveillance, expanded speed limit area… The Government of Canada is announcing new measures to prevent entanglements and collisions. These measures are being put into place following the discovery of six carcasses belonging to the endangered North Atlantic right whale. Additionally, three right whales have been observed entangled in fishing rope in recent weeks.
Slowing down to reduce risks
Restricting vessel speeds protects whales from collisions in two ways: by reducing the risk of serious or fatal injuries if a strike does occur, and by increasing the odds that a whale will have sufficient time to react and avoid the collision. Boats over 13 metres in length will now be restricted to a maximum speed of 10 knots, whereas in the past this measure only applied to vessels exceeding 20 metres. The slowdown sector has also been enlarged.
However, speed restrictions are not without major impacts to those ships making deliveries to remote areas, such as the N/M Bella-Desgagnés, which supplies provisions to North Shore communities that are inaccessible by land. Additionally, tourist vessels on the shores of the Gaspé Peninsula, whether they are international cruise liners or wildlife observation boats, must slow down to 10 knots.
This speed is not chosen at random. In several parts of the world, speed reduction measures to 10 knots have significantly curbed the risk of collision and especially collision-related mortalities. This measure is notably used at the entrance to the Panama Canal, one of the busiest shipping lanes in the world.
In search of entangled whales
Since June 29, three right whales have been spotted entangled in fishing rope, placing them in a vulnerable situation. Since then, the Campobello Whale Rescue Team, which specializes in right whale disentanglements, has been on the alert. But in the vast expanse of the Gulf of St. Lawrence, finding an entangled but freely swimming right whale is extremely difficult. Aerial surveillance flights have increased from twice weekly to twice daily. One of the three whales was spotted again on July 9, but it was already too late in the day to place a radio tag on the rope that it was dragging. With a tag, its movements could be tracked, making it easier to locate the animal and intervene.
In a message to the media, Fisheries and Oceans Canada states that it is encouraged by aerial surveillance conducted on July 9, during which a total of 90 North Atlantic right whales were observed swimming freely in the Gulf. These right whales were mostly in the static fishing closure area, where since late April no stationary, unattended gear – i.e. equipment left by fishermen for a few hours to a few days before being removed – can be deployed.
Strict measures vs. economic risks
Not only do these measures meet the survival requirements for the species, they are also compatible with economic imperatives related to seafood exports to the United States, the main market for eastern Canada. In 2017, such exports were valued at $4.3 billion. However, the United States has passed the Marine Mammal Protection Act, which stipulates that all countries exporting seafood products to the US must prove that they have marine mammal protection measures comparable to their own. By the end of July, Canada must submit an initial report on its efforts to mitigate the impacts of its fisheries on marine mammals. The legislation will come into effect on January 1, 2022, and if the US considers that Canada has not taken ample action, the country could lose its main market for lobster and snow crab.
Current regulations governing Canadian fisheries may seem extremely restrictive for fishermen, but they make the country one of the best performers in terms of the number of certified sustainable fisheries. Today’s measures to protect right whales are a step in this direction.
To learn more
News release announcing new measures (Government of Canada, July 8, 2019)
On the entanglements: an 86-minute presentation given by expert Amy Knowlton of the New England Aquarium and two fishermen (WGBHForum, August 6, 2018)
July 8 | A North Atlantic right whale… in France!
A reader has reported a video of an unusual-looking whale off the coast of Brittany, France. After validation with experts at the New England Aquarium, the organization that manages the North Atlantic right whale photo-ID catalogue, it turns out that it is a male right whale nicknamed Mogul. It is seen surface feeding, probably devouring copepods, the right whale’s favourite prey. This is the second observation of Mogul in the eastern Atlantic.
Mogul was born in 2008 to the female Slalom. He is seen annually by researchers in US waters and the Bay of Fundy on the Canadian side, mostly in coastal habitats and in the company of other right whales. But in late July 2018, Mogul was photographed off Iceland by a whale-watching outfitter. Nevertheless, Mogul had been seen on April 21, 2018 off the coast of Massachusetts. He completed his trans-Atlantic trip in under three months. In March 2019, Mogul was back on the North American side of the Atlantic. Which means he crossed the ocean again this year to Europe at an unknown date.
“Two things drive whale behaviour: food and reproduction. He was seen feeding, or at least trying to, in the video. He did not look sick from what we could see from the body on the video. And in March, he seemed well,” explains Heather Pettis, one of the scientists at the New England Aquarium.
Did he travel to France in search of food? Has he found enough food? The New England Aquarium team has not received any further sightings of Mogul since. Will we see him again in Europe in the coming months or years? It’s impossible to predict. Since 1986, a few right whales have been seen on the eastern side of the Atlantic, both in the Azores and in Norway. “It’s really rare to see a right whale in Europe,” confirms this expert.
If you see a whale at sea, it’s important to keep your distance. “Photos or videos that the public sends us are very useful, but it is essential to maintain a safe distance from the whale. They are much larger than what can be seen on the surface, so for one’s own safety, as well as for the safety of those on board the boat, an appropriate distance should be maintained,” adds Heather Pettis.
To learn more about Mogul in Iceland: A Rare Right Whale Sighting in Iceland (Anderson Cabot Center for Ocean Life, 2018)
Mogul’s page in the right whale photo-ID catalogue
July 2nd | Four Necropsies, Three Collisions
Preliminary results of the fourth North Atlantic right whale necropsy have just been announced by Fisheries and Oceans Canada. The whale known as Clipper probably died as a result of a ship strike. This result echoes that of two of the other three necropsies.
The necropsy was conducted on July 1 at the Grand-Étang rest stop near the town of Cloridorme in the Gaspé Peninsula. The work was a collaborative effort between teams of veterinarians from Université de Montréal and the Atlantic Veterinary College (University of Prince Edward Island), supported by US experts and volunteers from the Quebec Marine Mammal Emergency Response Network.
Clipper was first identified alive in the Gulf of St. Lawrence on June 4, 5 and 10. Then, on June 28, her carcass was spotted during aerial surveys conducted by Fisheries and Oceans Canada, approximately 100 km off the Gaspé Peninsula. This was the sixth carcass to have been found in Canadian waters in 2019.
First entangled right whale
On June 30, right whale #4400 was observed entangled in fishing gear off Miscou Island, New Brunswick. The juvenile right whale born in 2014 was in an area that had been closed off to fishing since April 28. The Campobello Whale Rescue Team, which specializes in disentangling whales, is waiting for better weather conditions before attempting an intervention. She has not been seen since.
June 25, 2019 | Second Right Whale Necropsy for 2019
The necropsy of the right whale known as Punctuation began on the morning of June 25. The carcass was first discovered on June 20, meaning it may already be in poor condition. Due to unfavourable weather conditions, only yesterday could the animal finally be towed to shore. The carcass is now in Petit-Étang, Nova Scotia.
Over the course of her life spanning nearly four decades, Punctuation gave birth to at least eight calves, the first being observed in 1986 and the most recent in 2016. The loss of a female of breeding age can hamper the recovery of an endangered species. During her lifetime, Punctuation got herself entangled no fewer than five times and was struck by a ship at least twice. Punctuation was seen in the Mingan Island sector in 2017.
Ironically, the discovery of this female’s carcass occurred on the same day as the publication of a study on the causes of North Atlantic right whale mortalities. Published in the scientific journal Diseases of Aquatic Organisms, the article confirms that entanglements and collisions are the most common causes of death for this species (88%), far ahead of natural causes. Researchers have examined the carcasses of 70 right whales found between 2003 and 2018, of which they were able to confirm the causes of death for 43 individuals. Of these, 22 died as a result of entanglement and 16 due to collisions with a ship. “The good news however, is that these mortalities are preventable if targeted and aggressive mitigation measures are enacted immediately by both the United States and Canada,” states Dr. Sarah Sharp, veterinarian and pathologist for the International Fund for Animal Welfare (IFAW).
Reduced speeds for ships, dynamic closure zones or rerouted shipping lanes, and the use of rope-less fishing gear are all avenues of protection that can be or have already been put into place.
To learn more:
Mortality study: Sharp, S.M., W.A. McLellan, D.S. Rotstein, A.M. Costidis et al. (2019) Gross and histopathologic diagnoses from North Atlantic right whale Eubalaena glacialis mortalities between 2003 and 2018. Dis Aquat Org 135:1-31. https://doi.org/10.3354/dao03376
June 7, 2019 | The First Right Whale Necropsy of 2019
The North Atlantic right whale identified as Wolverine is currently analyzed on Miscou Island, New Brunswick. The necropsy requires the contribution of nearly twenty people as well as heavy machinery. A right whale can measure up to 17 metres long and weigh up to 70 tonnes. Handling such a carcass is no easy task!
The animal was spotted on June 4 during an aerial survey conducted by the National Oceanic and Atmospheric Administration (NOAA), midway between the Gaspé Peninsula and Miscou Island, i.e. 50 nautical miles from each. It was in a fishing area that had been closed off since May 17 in a precautionary measure to prevent entanglements. On June 5, the CCGS A. LeBlanc, a Canadian Coast Guard ship, began towing the carcass to New Brunswick. After nearly 13 hours, ship and whale are near the coast in anticipation of the necropsy, which is being performed on June 7.
A necropsy is the equivalent of an autopsy in humans, and consists of a comprehensive analysis of the animal. Thanks to necropsies, expert veterinarians were able to conclude that of the twelve right whales found dead in 2017, two mortalities were related to entanglement in fishing gear, four were attributable to collisions with ships and the cause of one death remained undetermined. For the time being, neither the cause or exact timing of Wolverine’s death have been able to be determined based on observations of the carcass.
Specialized teams of veterinarians, biologists and marine mammal experts from Fisheries and Oceans Canada, the Marine Animal Response Society, the Atlantic Veterinary College of the University of Prince Edward Island and Université de Montréal will collaborate in the necropsy. It may be several months before the results of the analyses become available.
June 6, 2019 | Right Whale Carcass Found Adrift in Gulf of St. Lawrence
A first North Atlantic right whale carcass has been discovered this year. North Atlantic right whales are considered endangered and their population is estimated to number 411 individuals. The carcass was spotted on June 4 during an aerial survey carried out by the US National Oceanic and Atmospheric Administration (NOAA). It was approximately 50 nautical miles from the Gaspé coast.
Overflights by Fisheries and Oceans Canada and patrols by the Canadian Coast Guard were carried out on June 5 to relocate the animal. Fisheries and Oceans Canada, the Quebec Marine Mammal Emergency Response Network and the Marine Animal Response Society are evaluating the possibility of towing the carcass to Miscou Island for analysis in the coming days. A comprehensive necropsy might help determine the cause of the animal’s death.
The logistical challenges of transporting a North Atlantic right whale are multiple, given the size and weight of the individual. The distance to the coast (approx. 13 hours away) adds to the complexity of the operation. Organizing a necropsy also requires expertise and a sizable workforce to carve up the enormous body. Nevertheless, the answers that might be provided by the analysis could serve to better inform conservation measures.
A right whale named Wolverine
The New England Aquarium team has identified the right whale. It is Wolverine, a male born in 2010 to female 3123. He owed his name to three large scars at the base of his tail, the result of a collision with an engine propeller when he was 5 years old. During the first five years of his life, Wolverine was seen entangled three times, with two of these entanglements considered minor and one moderate, according to the standards developed by the New England Aquarium. This individual was seen in 2017 and 2018 in the Gulf of St. Lawrence. At the current time, we do not know the cause of the mortality.
A changing ecosystem
Part of the North Atlantic right whale population has traditionally spent summers in the Bay of Fundy. Since 2017, the Bay of Fundy appears to be less heavily visited and a major increase in right whale sightings has been noted in the Gulf of St. Lawrence. In 2017, twelve right whale carcasses were found in the Gulf. Mitigation measures to lower the risks of entanglement and collisions were urgently implemented that summer. Measures were also applied in 2018; no carcasses were found that year. This year, speed reduction zones and mitigation measures have once again been put into place.
To dive deeper
Wolverine’s portrait (New England Aquarium)
May 27, 2019 | Right Whales: Fishing Closures and New Technologies for Crabbing Industry
On May 13, the first North Atlantic right whales of the season were observed via aerial survey in the Gulf of St. Lawrence. Their return to Canadian waters has meant the implementation of a number of protective measures, including speed restrictions for boats exceeding 20 metres as well as the closure of certain fishing areas. A static speed reduction zone, which represents the region where 90% of right whales were observed in 2018, has been in effect since April 28.
The purpose of these measures is to lower the risk of collisions and entanglements, which are significant threats to the endangered North Atlantic right whale. These measures were adopted in the aftermath of the exceptional mortality incidents of 2017, when 17 right whale carcasses were discovered, including 12 in Canadian waters. Recap of the latest news with regard to right whales…
New technologies for crabbers
The Acadian Crabbers Association will receive funding of over $2 million over three years to test new fishing techniques that might help lower the risk of right whale entanglements. The crabbing industry, a fishery that many coastal communities depend on for their livelihood, involves the use of huge quantities of rope. Because they spend a great deal of time foraging at the surface, right whales are particularly at risk of finding themselves ensnared in these ropes.
The current method consists of tethering the crab traps – which sink to the seabed – to a buoy that floats on the surface. Since last summer, crabbers have been testing new fishing techniques. For example, underwater buoys might represent a viable alternative since they eliminate the need for any rope near the surface. These buoys could be combined with an acoustic system that would enable crabbers to “call” their buoys back to the surface whenever they wish to check their traps.
Adapting to the presence of right whales
Right whales now visit the Gulf of St. Lawrence in large numbers, which was not the case a decade ago. They are believed to be in search of new food sources, as copepods have become less plentiful in their traditional feeding grounds in the Bay of Fundy.
Protective measures were hastily introduced in 2017, then renewed the following year. In 2018, not a single right whale carcass was found in Canada. Is this proof that the imposed restrictions are effective? It’s hard to say. “What we do know is that these efforts will have to be maintained for several years,” explains Robert Michaud in an interview with Radio-Canada. The longevity of right whales and the long intervals between births mean that the results of any conservation measures will take time to become apparent.
Right whales in statistics
Number of Individuals: 411
Number of calves counted in 2019: 7
Number of calves counted in 2018: 0
Calving interval per female: 10 years
Proportion of individuals with markings caused by entanglement: 83%
Speed limit: 10 knots
Duration of protection of an area following a right whale sighting: 15 days
February 8, 2019 | Right Whales: Similar Measures for 2019
The North Atlantic right whale protection measures for 2019 have been announced, and will include measures better suited to the fishing industry, as well as constant monitoring efforts similar to last year. Fisheries and Oceans Minister Jonathan Wilkinson and Transport Minister Marc Garneau reiterated the importance of protecting this endangered species. Aerial and acoustic monitoring will continue with the same intensity to document the presence of right whales. The two ministers, however, announced a few adjustments in the measures compared to 2018 to reduce the impacts of these measures on coastal communities.
Adapted fishing measures
One area will be closed to fishing activities for the season beginning April 28, or earlier if a right whale is detected there. The season-long closure area is roughly 63% smaller than that of 2018 and corresponds to the area where 90% of right whale sightings were made last summer.
Temporary closure areas have also been designated. A closure occurs when at least one right whale is seen in the area. The area will then be closed for a period of 15 days, during which all fishing gear must be taken out of the water.
In response to requests from the lobster fisheries, shallow areas (20 fathoms or less) will automatically be closed only if a right whale is also observed in shallow waters.
Slowing down to prevent collisions
Speed limit zones of 10 knots will be reinstated beginning April 28 for commercial vessels 20 metres and more. A regular speed corridor will be established and will only be closed in the event right whales are observed, which will notably allow cruise and supply vessels to easily reach coastal regions without necessarily altering their schedules.
All measures are in response to the 2017 right whale mortality episode when 12 carcasses were discovered in Canadian waters. In order to maintain its seafood export permits and comply with its Species at Risk legislation, the Government of Canada established emergency measures during the 2017 season, introduced more stringent measures in 2018 and adapted them this year.
January 23, 2019 | Six Newborn Right Whales: A Glimmer of Hope
Since North Atlantic right whales have left the frigid waters of the Gulf of St. Lawrence to return to their wintering grounds, four calves have been observed by the Florida Fish and Wildlife Conservation Commission. They were seen in Florida on December 28, 2018 and January 13, 2019 and are the first of the calving season, which generally runs from November to February. According to Julie Albert, coordinator for the Marine Resources Council, we can expect more births before the end of the season, as “5 of the 6 whales spotted this season may have been pregnant females,” she reports to the Daytona Beach News-Journal. Low birth rates have been observed in this endangered species since 2010. Each birth therefore represents a tiny step toward an eventual recovery.
“5 of the 6 whales spotted this season may have been pregnant females,” she reports.
Births in the context of declining fertility
The North Atlantic right whale population is estimated to number 411 individuals. Of these, about 75 are believed to be females of reproductive age. However, in 2018, no calves were observed and only 5 were spotted in 2017. The number of calves observed each year is therefore quite different from what would normally be expected. Between 2010 and 2016, the birth rate fell by 40%. Additionally, the average interval between births for any given female rose from 4 to 10 years. For comparison, this interval is 3 years for the species’ cousin, the southern right whale. The decrease in the number of completed pregnancies and the increase in the number of undocumented newborn deaths are reasons that might explain these unusual intervals.
Pregnancy and nursing are very energy-intensive processes for females, who require access to sufficient food sources to maintain their body weight. Copepods – a favourite food of right whales – are becoming increasingly rare in traditional summer areas between New England and Nova Scotia. This might explain why a growing number of right whales are being observed in the Gulf of St. Lawrence, where these small crustaceans are present. A longer migration means greater energy expenditures for females, which can be detrimental to reproduction. If, despite the odds weighing against her, the female does manage to give birth to a calf, there is no guarantee that she will be sufficiently fit to produce enough milk to feed her offspring. Indeed, studies on the southern right whale have shown that the body volume of lactating females diminishes by 25% in a span of just 3 months.
In recent decades, there has been a correlation between particularly low birth rates and the observation of more injuries and poorer health overall. This suggests that the low birth rate may be related to the frequent entanglements of North Atlantic right whales in fishing gear. This species is particularly prone to collisions and entanglements, as it is a slow swimmer and stays close to the surface. The stress triggered by these events can affect whales’ reproduction or their ability to terminate their pregnancy. Fortunately, these periods are generally followed by a rise in birth rates when health conditions become favourable again.
Further, the low genetic diversity of right whales might be having an effect on their reproductive capacity. Indeed, small populations are particularly at risk when it comes to mating between individuals that are too closely related genetically. Such individuals may be genetically incompatible and produce non-viable fetuses.
The introduction of right whale protection measures in 2018 by Fisheries and Oceans Canada and Transport Canada appears to have been effective. Authorities have identified 3 entanglements and zero mortalities in Canadian waters in the past year, a dramatic improvement compared to the 18 mortalities and 5 entanglements documented in 2017.
We will need to wait a few years before we can determine whether the decrease in mortality and stressful events will translate into higher birth rates. In the meantime, it is hoped that these three births will be the harbinger of a string of good news for the species.
(2010) Browning, C., R.M. Rolland and S.D. Kraus. Estimated calf and perinatal mortality in western North Atlantic right whales (Eubalaena glacialis). (United States.) Marine Mammal Science 26(3): 648-662.
(2018) Christiansen, F., F. Vivier, C. Charlton, R. Ward, A. Amerson, S. Burnell and L. Bejder. Maternal body size and condition determine calf growth rates in southern right whales. (Australia.) Marine Ecology Progress Series 592: 267–281.
(2018) Right Whale News 26(3): 1-21.