Latest news with #JaneMcPhee-Frew
Yahoo
20-05-2025
- Science
- Yahoo
Humpback whales can give birth while migrating thousands of miles
Humpback whales (Megaptera novaeangliae) are master migrators. Some populations of this baleen whale species travel upwards of 5,000 miles per year from colder waters to feed, towards warmer tropical waters where they give birth and care for their calves. However, new research on a population off Australia's eastern coast indicates that their trips to more balmy waters are not as essential to calving as biologists thought. Calves in this population can actually be born in colder waters near New Zealand or Tasmania–about 932 miles further south (1,500 kilometers) than previously known. Understanding this pattern could challenge some long-held beliefs about humpback migration and improve protection areas to help these baby whales. The findings are detailed in a study published May 20 in the journal Frontiers in Marine Science. 'Hundreds of humpback calves were born well outside the established breeding grounds,' said Tracey Rogers, a study co-author and marine ecologist at the University of New South Wales in Australia. 'Giving birth along the 'humpback highway' means these vulnerable calves, who are not yet strong swimmers, are required to swim long distances much earlier in life than if they were born in the breeding grounds.' In the Northern Hemisphere, humpback whales like those found on the east coast of the United States and Canada, typically migrate from colder feeding in the Northern Atlantic Ocean in the summer and south to the Caribbean for the winter to breed and calf. For Southern Hemisphere humpbacks like those off the coast of Eastern Australia, the directions are flipped because of the equator. They travel from their frigid feeding grounds in the Southern Ocean around Antarctica, north towards the Pacific Ocean in Australia to breed, calve, and care for their young. Finding this new baby whale hotspot arose due to study co-author and University of New South Wales Ph.D candidate Jane McPhee-Frew's extracurricular work as a marine guide. 'In July 2023, during a whale-watching tour, I encountered a mum and calf at the mouth of Newcastle Harbor—the busiest shipping port in Eastern Australia,' said McPhee-Frew. 'The calf was tiny, obviously brand new. What were they doing there? But none of my tourism colleagues seemed surprised.' This new sighting piqued researchers' interest and they began investigating the calving range for humpback whales located around Australia and New Zealand. They used data from citizen science observations, government surveys, and reported strandings. New Zealand's Department of Conservation Cook Strait Whale Project supplied data from migration surveys, and Australian state wildlife departments supplied information on strandings dating all the way back to 1991. The team found 209 records of newborn calves (including 11 births), 41 strandings, and 168 observations of live calves, representing at least 169 individual whales. They also had data on the direction of travel for 118 whales, which showed the whales were continuing to migrate north after delivery. 'Humpback whale populations undertake extensive long-distance migrations from the Southern Ocean to breeding grounds in the tropics,' said study co-author Adelaide Dedden of the National Parks and Wildlife Service, Australia. 'They rely heavily on body reserves from an enormous amount of Antarctic krill to support the physiological costs of the journey and reproduction.' The highest-latitude calf was found at Port Arthur, Tasmania–about 932 miles further south than it was believed that humpbacks could calf. When they compared these observations taken over the last decade with historical texts and whaling logbooks, they say that calves born during migration were observed more often before the population crashed due to hunting. Humpback whale numbers in Australia crashed during the peak of the whaling industry, particularly during the 1960s and 1970s. 'I think it's very likely that this pattern has always existed, but the low number of whales obscured it from view,' said McPhee-Frew. 'The Eastern Australia humpback population narrowly escaped extinction, but now there are 30, 40, or 50,000 in this population alone. It doesn't happen overnight, but the recovery of humpback whales, and the return of their full range of behaviors and distribution, just goes to show that with good policies built on good science we can have excellent outcomes.' For all migratory species, these epic journeys cost a great deal of time and energy. The energy expenditures can leave their young vulnerable to predators. While this particular study can't answer why humpback whales risk migrating if they can give birth further south, it's possible that other factors are driving migration. The benefits of delivering in tropical waters might outweigh the risks of having a potential calf born along the way. While the data provided by Western Australia's Department of Biodiversity, Conservation, and Attractions pinpointed a possible nursery area in Flinders Bay, it's likely that most calves are born much further north in the tropics. [ Related: Humpback whales use bubble-nets as 'tools.' ] According to the team, there are several conservation implications in these findings. Some of the observed calves were injured, so expanded protected areas, awareness campaigns about protective measures boaters and the general public can take, and more research into the habitats that humpbacks use while migrating are critical to safeguarding the calves. 'This study was based on opportunistic observations,' cautioned McPhee-Frew. 'This data is excellent for answering questions like, 'are there newborn whales here?' But we can't stretch the interpretations too far. It might appear that we see more calves the further north we go, or that we have seen more over time. But it could be that there are more people whale-watching in the north, or more cameras and social media sharing in recent years.' 'We can only document what we see,' added study co-author Vanessa Pirotta of Macquarie University in Australia. 'Perhaps there are things happening in our ocean that we are yet to find out.'
ABC News
20-05-2025
- Science
- ABC News
Humpback whales have babies much further south than previously thought
Humpback whales are on the move again. At this time of year, the whales travel up the eastern and western sides of Australia, treating viewers on the coast to a show. They're migrating from cold, krill-rich southern waters to spend their winters in the warmer seas north of the continent, which are the whales' breeding grounds. You may even see mums with newborn humpbacks on the northern route well before they reach the tropics, according to a new study. The study challenges assumptions about where humpback whales breed, and possibly why they migrate, according to lead author Jane McPhee-Frew. And observations by citizen scientists played a key role in the findings. Until now, many researchers believed whales only gave birth to calves in warmer tropical waters. But the study, published in Frontiers in Marine Science, found records of baby humpbacks in the east as far south as Tasmania and New Zealand. Humpback whales occur in every ocean around the world, with both northern hemisphere and southern hemisphere populations moving between their respective poles and the tropics. They were nearly hunted to extinction by the mid-20th century, but their numbers have since rebounded, with tens of thousands now migrating up the Australian coasts. Each year begin their northward migration from April, and return south between August and November. Around Australia, humpbacks generally weren't thought to give birth further south than 28 degrees latitude in the east (near the Gold Coast), or 23 degrees in the west (just south of Exmouth). "Our general concept of humpback whale ecology is that they feed at high latitudes in the poles, breed in the tropics, and they have this migration that's driven between the two needs," Ms McPhee-Frew said. Ms McPhee-Frew, a PhD candidate at the University of New South Wales, had been surprised to see a very young whale while working as a tour guide in Newcastle in 2023. "I saw a newborn right at the mouth of Newcastle Harbour," she said. Her PhD supervisor was also surprised, but Ms McPhee-Frew's colleagues in tourism weren't. They had apparently seen baby humpbacks in colder southern waters. This prompted Ms McPhee-Frew and fellow ecologists to search for more records of newborn whales south of the tropics. "We clearly have a gap here," she said. The researchers compiled records of baby humpback whales from a range of sources: government agencies, migration surveys and citizen science records from places like tourism boat trips. They found records of more than 200 newly-born whale calves appearing further south than the previously assumed limit. Some of the neonates were recorded at 43 degrees south, in the waters around Tasmania and New Zealand. This was as far south as the observations went, so it's possible that humpbacks were giving birth even closer to Antarctica. This means the whales don't need to breed in warmer waters — although they might prefer to. The baby whales were born while their mothers were heading north, towards the tropics. Olaf Meynecke, a whale researcher at Griffith University who wasn't involved in the study, said the results were "not surprising". Dr Meynecke and his colleagues had seen newly-born humpbacks well south of their traditional breeding grounds in the past decade, all heading north. "We know that they undertake all important behaviour — feeding, mating and birthing — not only in dedicated areas, but also along their migratory corridor," Dr Meynecke said. If the humpback whales don't need to breed in the tropics, why are they migrating thousands of kilometres to do it? "I don't know, but it's exciting," Ms McPhee-Frew said. It may be that whales born in the tropics are still better off. Ms McPhee-Frew pointed out a number of "really obvious" benefits to warmer waters: they're better for baby whales with poor temperature regulation, they're calmer, and they have fewer predators such as orcas. Dr Meynecke says that while humpbacks can give birth in cooler waters, they still migrate north to "ensure faster growth rates" for their calves. "With an expansion of the population and higher stress on food availability during summer feeding, it may be an advantage to give birth further south," Dr Meynecke said. But there could also be other factors driving the migration. "Is it that the female is just driven north through some deep either cultural or genetic instinct?" Ms McPhee-Frew said. Either way, studying baby whales born in cold waters will help researchers find out. If these calves grow up worse off than their warm-water peers, that will show that there really is a good reason to migrate for breeding, she said. "What we have now is this really important comparison group." Dr Meynecke wants to see systematic studies on the mothers and calves who are born mid-migration, to learn more about their true numbers and behaviours. He said it would be interesting to know the effect of being born during migration on an individual calf. "Will it return to the same waters where it was born for reproduction?" he asked. Ms McPhee-Frew, meanwhile, recommended that people keen to see whales book in tours with local responsible operating groups — both for the fun of seeing them, and because their observations may help further research. There are a number of citizen science projects in many states. If you're planning to do some whale watching this winter, you can help researchers wherever you are along the coast by logging your observations. If you're interested in drone photography, note there is a blanket rule of keeping drones at least 100m away from marine animals including whales. Each state may have additional rules. Ms McPhee Frew said photographers should include the distance (and zoom or photography settings) in the caption when posting pictures. "We encourage people to enjoy these lovely animals, provided they're following the rules that are in place for the whales' protection," she said.
