Latest news with #OurChangingWorld
RNZ News
01-07-2025
- Science
- RNZ News
Our Changing World: Protecting 'Jaws'
By Karthic SS for Our Changing World Checking traps for the lowland longjaw galaxias. Photo: Karthic SS Tiny, rare and under the radar. Just a few streams in Twizel, in the upper Waitaki catchment, are home to one of New Zealand's rarest fish: the lowland longjaw galaxias. Follow Our Changing World on Apple , Spotify , iHeartRadio or wherever you listen to your podcasts "If you look closely, you can see the lower jaw is longer than the upper jaw - sort of like a bulldog... We affectionately call them 'Jaws'," says Department of Conservation senior ranger for biodiversity Dean Nelson. Unlike their namesake, these 'Jaws' are tiny, growing up to just eight centimetres. Dean has been working to protect these small, brown-speckled fish for more than two decades in Twizel. "They get under your skin a bit, you really get wound up about them. They've become my big passion these days," he says. Dean Nelson checking traps. Photo: Karthic SS There are two genetically distinct lowland longjaw populations: one in the Upper Waitaki catchment and the other in the Kauru Kakanui river in Otago. "They are treated as different species, but both are called lowland longjaws," says Dean. Lowland longjaws are related to whitebait. Both are part of a family called Galaxiidae. This family of fishes is named for the gold flecks on their backs that resemble a starry galaxy pattern. But there's one big difference. The whitebait species are migratory: adults migrate to the coast to spawn, and their young swim back upstream, where they are caught as whitebait. Lowland longjaw galaxias. Photo: Dean Nelson In contrast, lowland longjaw galaxias are homebodies. They are non-migratory, spending all their lives in the same gravely stream they hatch in. New Zealand is home to 12 species of non-migratory galaxiids, plus 13 groups that are yet to be formally described and confirmed as a species. All of them have been classified to be 'at risk' or 'threatened', as most of the populations are fragmented and prone to local extinctions. Lowland longjaw galaxias (the smaller fish, on the left). Photo: Karthic SS The Waitaki lowland longjaws are 'nationally endangered', which means they are at risk of extinction in the short term. Just seven known populations remain. They face various threats such as invasive plants, land use changes, and introduced trout. Brown and rainbow trout from the northern hemisphere were released into the rivers of Aotearoa in the mid-to-late 19th century for sports fishing. They are one of the main threats to the lowland longjaw galaxias. A brown trout eating a bignose galaxias. Photo: Dean Nelson Trout can move through river systems, and when they get into streams and tributaries, they feed on native fish like the longjaw and other non-migratory galaxiids, causing a dramatic decline in their numbers. At a field site near Twizel, Dean has witnessed this decline himself. "We knew trout were here in Fraser Stream and hadn't done anything about it, and in 2009 we suddenly found that we were only getting a handful of fish. "I think we caught 12 lowland longjaw and 25 bignose galaxiids in the stream. And we went, 'Uh oh, that's no good!' So we put a barrier in. That was our first barrier, and we've since modified it and changed it." Fraser Stream landscape barrier. Photo: Karthic SS Martha Jolly, a PhD Candidate at the University of Canterbury, is studying how these artificial barriers and other interventions can help turn things around for the lowland longjaw. "It's quite similar to fenced reserves in terrestrial conservation, where you might put a fence around a precious species and do predator removal to protect that species." The barriers are designed to keep trout out of the habitat by creating a drop they can't jump. There are now 12 built barriers in the upper Waitaki catchment. The barrier at the Waterwheel Wetland. Photo: Martha Jolly "Some of our galaxias species just really cannot co-occur with trout. They tend to get predated on, and end up going extinct pretty quickly. "Nobody is saying that we want to get rid of trout from our waterways at all. And what we're finding with the non-migratory galaxiid habitat is that actually it's tiny fragments, which isn't ideal for trout fishery, anyway. "There's plenty of room for everybody. There are just some habitats where these introduced sports fish are really not helpful, and have a negative impact on our native fish." Flood over the trout barrier at Fraser Stream, August 2022. Photo: Dean Nelson Frequent monitoring of streams is crucial. Extreme weather events can result in floods that flow over the top of barrier, meaning trout get back into longjaw habitat. Both Martha and Dean believe that the barriers alone might not be enough, and in the future, they might have to consider other conservation efforts. In the meantime, Dean says, they are using environmental DNA to help them search for more tiny 'Jaws'. "I still hold hope that one day we'll find another population that we didn't know about that's surviving somewhere." Sign up to the Our Changing World monthly newsletter for episode backstories, science analysis and more.
Scoop
22-05-2025
- Science
- Scoop
Our Changing World: Dissecting The World's Rarest Whale
Article – RNZ It made international headlines last year. What does a scientific dissection of the world's rarest whale involve? , for Our Changing World The spade-toothed whale: deep diving, rare, and largely unknown to science – until now. The elusive species, part of the beaked whale family, grabbed worldwide headlines in 2024: first when it washed ashore 30 minutes south of Dunedin in July, then again five months later when it was dissected. In December 2024, Our Changing World joined the research team during their week-long scientific dissection efforts to find out what secrets the whale holds. Rare and elusive Beaked whales are some of the most elusive marine mammals on the planet because they are so incredibly well adapted to their long-deep-diving lifestyle. Satellite tagging studies of Cuvier's (or goose-beaked) whales have revealed extraordinary feats of physiology. This includes one dive that lasted a mindboggling 222 minutes – that's longer than the runtime of The Return of the King, the third (and longest) Lord of the Rings movie. Another dive reached a depth of almost three kilometres. Average dives lasted about one hour – impressive breath-holding for an air-breathing mammal. As for the spade-toothed whale's diving prowess – well, nobody knows. It's never been seen alive in the wild. 'I can't tell you how extraordinary it is for me personally' Anton van Helden helped give the whale its common name – spade-toothed – because the single tusk-like tooth erupting from the lower jaw of males looks like a whaling tool called a spade. Anton, senior science advisor in the marine species team at the Department of Conservation, had described the outer appearance of the whale from photographs taken of a mother and calf that washed up in the Bay of Plenty in 2010. They were originally mis-identified and buried, before DNA analysis confirmed that they were spade-toothed whales, after which their partial skeletons were exhumed. This meant that when Anton was sent some snaps of the whale that washed up in Otago in July 2024 he knew exactly what he was looking at, and what a rare find it was. The 2024 specimen is only the seventh ever found (with all but one from New Zealand). Hence the hum of excitement in the concrete room at AgResearch's Invermay campus in Mosgiel, just south of Dunedin. For the first time ever, scientists got the chance to dissect an intact spade-toothed whale. New finds: nine stomachs and tiny teeth The week begins with photographs and whole-body measurements, followed by cutting into and peeling back the thick layer of blubber. Once the blubber is removed, individual muscles are identified and documented. The massive backstrap muscle across the length of the body is then removed, exposing the organs below. These are photographed, examined and weighed. Each beaked whale species seems to have a unique stomach plan. This dissection revealed that the spade-toothed whale has nine stomachs. Squid beaks and eye lenses were found inside, along with some parasites that are now at the University of Otago, awaiting identification. During the week the intact head was removed and brought to the onsite CT scanner. The tens of thousands of images that come out of the scan, along with the subsequent head dissection, will help the researchers dig into some of the many questions they have around the whale's evolution, how they make and use sound, and how they feed. For example, tiny vestigial teeth were found in the jawbone of this whale – a throwback to their early evolutionary days when they had more teeth. Now they have evolved to be suction feeders, using sound to echolocate their prey and then employing their piston-like tongue to alter the water pressure and suck them in. While the focus was scientific dissection, rather than autopsy, the team did find bruising around the neck and head, and a broken jawbone, indicating that the whale had suffered some head trauma that was likely the cause of death. A collaborative effort, and a reconnection A large team participated in the whale's recovery and dissection: Te Rūnanga o Ōtākou hapū members and rangatahi, staff from Tūhura Otago Museum, local and international whale scientists, University of Otago staff and scientists, Māori whale experts (tohunga), and staff from the Department of Conservation. Experts from both knowledge systems – mātauranga Māori and western science – worked alongside each other, with learning going both ways, says Tumai Cassidy from Te Rūnanga o Ōtākou. He was excited to learn from Ngātiwai tohunga Hori Parata and his son Te Kaurinui who answered Te Rūnanga o Ōtākou's call to assist with the dissection. The whale was named Ōnumia by the rūnanga, after the te reo Māori name for the native reserve stretch of coastline it was found on. The whale's skeleton has been gifted to Tūhura Otago Museum, but it will be a while before it will go on display. Right now, the bones are in Lyttelton in the care of Judith Streat. Three months in bacteria-filled baths have stripped the bones of flesh, but there is a lot of oil in deep-diving whales, so the process will take several more years. The kauae, or jawbone, will stay with Te Rūnanga o Ōtākou, says Rachel Wesley. 'Being able to claim the kauae, you know, as mana whenua, under our rakatirataka and in line with old practices from the past has been a huge step forward from what our hapū has been able to do in the past.' A 3D-printed version of the jawbone will complete the skeleton in the museum.
Scoop
22-05-2025
- Science
- Scoop
Our Changing World: Dissecting The World's Rarest Whale
The spade-toothed whale: deep diving, rare, and largely unknown to science - until now. The elusive species, part of the beaked whale family, grabbed worldwide headlines in 2024: first when it washed ashore 30 minutes south of Dunedin in July, then again five months later when it was dissected. In December 2024, Our Changing World joined the research team during their week-long scientific dissection efforts to find out what secrets the whale holds. Rare and elusive Beaked whales are some of the most elusive marine mammals on the planet because they are so incredibly well adapted to their long-deep-diving lifestyle. Satellite tagging studies of Cuvier's (or goose-beaked) whales have revealed extraordinary feats of physiology. This includes one dive that lasted a mindboggling 222 minutes - that's longer than the runtime of The Return of the King, the third (and longest) Lord of the Rings movie. Another dive reached a depth of almost three kilometres. Average dives lasted about one hour - impressive breath-holding for an air-breathing mammal. As for the spade-toothed whale's diving prowess - well, nobody knows. It's never been seen alive in the wild. 'I can't tell you how extraordinary it is for me personally' Anton van Helden helped give the whale its common name - spade-toothed - because the single tusk-like tooth erupting from the lower jaw of males looks like a whaling tool called a spade. Anton, senior science advisor in the marine species team at the Department of Conservation, had described the outer appearance of the whale from photographs taken of a mother and calf that washed up in the Bay of Plenty in 2010. They were originally mis-identified and buried, before DNA analysis confirmed that they were spade-toothed whales, after which their partial skeletons were exhumed. This meant that when Anton was sent some snaps of the whale that washed up in Otago in July 2024 he knew exactly what he was looking at, and what a rare find it was. The 2024 specimen is only the seventh ever found (with all but one from New Zealand). Hence the hum of excitement in the concrete room at AgResearch's Invermay campus in Mosgiel, just south of Dunedin. For the first time ever, scientists got the chance to dissect an intact spade-toothed whale. New finds: nine stomachs and tiny teeth The week begins with photographs and whole-body measurements, followed by cutting into and peeling back the thick layer of blubber. Once the blubber is removed, individual muscles are identified and documented. The massive backstrap muscle across the length of the body is then removed, exposing the organs below. These are photographed, examined and weighed. Each beaked whale species seems to have a unique stomach plan. This dissection revealed that the spade-toothed whale has nine stomachs. Squid beaks and eye lenses were found inside, along with some parasites that are now at the University of Otago, awaiting identification. During the week the intact head was removed and brought to the onsite CT scanner. The tens of thousands of images that come out of the scan, along with the subsequent head dissection, will help the researchers dig into some of the many questions they have around the whale's evolution, how they make and use sound, and how they feed. For example, tiny vestigial teeth were found in the jawbone of this whale - a throwback to their early evolutionary days when they had more teeth. Now they have evolved to be suction feeders, using sound to echolocate their prey and then employing their piston-like tongue to alter the water pressure and suck them in. While the focus was scientific dissection, rather than autopsy, the team did find bruising around the neck and head, and a broken jawbone, indicating that the whale had suffered some head trauma that was likely the cause of death. A collaborative effort, and a reconnection A large team participated in the whale's recovery and dissection: Te Rūnanga o Ōtākou hapū members and rangatahi, staff from Tūhura Otago Museum, local and international whale scientists, University of Otago staff and scientists, Māori whale experts (tohunga), and staff from the Department of Conservation. Experts from both knowledge systems - mātauranga Māori and western science - worked alongside each other, with learning going both ways, says Tumai Cassidy from Te Rūnanga o Ōtākou. He was excited to learn from Ngātiwai tohunga Hori Parata and his son Te Kaurinui who answered Te Rūnanga o Ōtākou's call to assist with the dissection. The whale was named Ōnumia by the rūnanga, after the te reo Māori name for the native reserve stretch of coastline it was found on. The whale's skeleton has been gifted to Tūhura Otago Museum, but it will be a while before it will go on display. Right now, the bones are in Lyttelton in the care of Judith Streat. Three months in bacteria-filled baths have stripped the bones of flesh, but there is a lot of oil in deep-diving whales, so the process will take several more years. The kauae, or jawbone, will stay with Te Rūnanga o Ōtākou, says Rachel Wesley. "Being able to claim the kauae, you know, as mana whenua, under our rakatirataka and in line with old practices from the past has been a huge step forward from what our hapū has been able to do in the past." A 3D-printed version of the jawbone will complete the skeleton in the museum.
RNZ News
21-05-2025
- Science
- RNZ News
Our Changing World: Dissecting the world's rarest whale
It's only the seventh time a spade-toothed whale has been documented worldwide, and the first time a complete specimen has been recovered in good condition for examination. Photo: RNZ / Tess Brunton Follow Our Changing World on Apple , Spotify , iHeartRadio or wherever you listen to your podcasts The spade-toothed whale: deep diving, rare, and largely unknown to science - until now. The elusive species, part of the beaked whale family, grabbed worldwide headlines in 2024: first when it washed ashore 30 minutes south of Dunedin in July, then again five months later when it was dissected . In December 2024, Our Changing World joined the research team during their week-long scientific dissection efforts to find out what secrets the whale holds. Beaked whales are some of the most elusive marine mammals on the planet because they are so incredibly well adapted to their long-deep-diving lifestyle. Satellite tagging studies of Cuvier's (or goose-beaked) whales have revealed extraordinary feats of physiology. This includes one dive that lasted a mindboggling 222 minutes - that's longer than the runtime of The Return of the King , the third (and longest) Lord of the Rings movie. Cuvier's beaked whales are renowned for their deep and long dives, stretching for more than three hours. Photo: Laurent Bouveret / CC BY-SA 4.0 via Wikimedia Another dive reached a depth of almost three kilometres. Average dives lasted about one hour - impressive breath-holding for an air-breathing mammal. As for the spade-toothed whale's diving prowess - well, nobody knows. It's never been seen alive in the wild. Anton van Helden helped give the whale its common name - spade-toothed - because the single tusk-like tooth erupting from the lower jaw of males looks like a whaling tool called a spade. DOC rangers assess a washed up whale, thought to be a spade-toothed whale, on the beach at Taieri Mouth. Photo: Supplied/Department of Conservation Anton, senior science advisor in the marine species team at the Department of Conservation, had described the outer appearance of the whale from photographs taken of a mother and calf that washed up in the Bay of Plenty in 2010. They were originally mis-identified and buried, before DNA analysis confirmed that they were spade-toothed whales, after which their partial skeletons were exhumed. This meant that when Anton was sent some snaps of the whale that washed up in Otago in July 2024 he knew exactly what he was looking at, and what a rare find it was. The 2024 specimen is only the seventh ever found (with all but one from New Zealand). Spade-toothed Whale Photo: Ōnumia CC BY 4.0 DOC Hence the hum of excitement in the concrete room at AgResearch's Invermay campus in Mosgiel, just south of Dunedin. For the first time ever, scientists got the chance to dissect an intact spade-toothed whale. The week begins with photographs and whole-body measurements, followed by cutting into and peeling back the thick layer of blubber. Scientists are starting the examination in Mosgiel, which is expected to take several days. Photo: RNZ / Tess Brunton Once the blubber is removed, individual muscles are identified and documented. The massive backstrap muscle across the length of the body is then removed, exposing the organs below. These are photographed, examined and weighed. Each beaked whale species seems to have a unique stomach plan. This dissection revealed that the spade-toothed whale has nine stomachs. Squid beaks and eye lenses were found inside, along with some parasites that are now at the University of Otago, awaiting identification. During the week the intact head was removed and brought to the onsite CT scanner. The tens of thousands of images that come out of the scan, along with the subsequent head dissection, will help the researchers dig into some of the many questions they have around the whale's evolution, how they make and use sound, and how they feed. The whale head is lifted into the CT scanner. Photo: Claire Concannon / RNZ For example, tiny vestigial teeth were found in the jawbone of this whale - a throwback to their early evolutionary days when they had more teeth. Now they have evolved to be suction feeders, using sound to echolocate their prey and then employing their piston-like tongue to alter the water pressure and suck them in. While the focus was scientific dissection, rather than autopsy, the team did find bruising around the neck and head, and a broken jawbone, indicating that the whale had suffered some head trauma that was likely the cause of death. A large team participated in the whale's recovery and dissection: Te Rūnanga o Ōtākou hapū members and rangatahi, staff from Tūhura Otago Museum, local and international whale scientists, University of Otago staff and scientists, Māori whale experts (tohunga), and staff from the Department of Conservation. With the blubber removed, the team start investigating the muscles below. Photo: Claire Concannon / RNZ Experts from both knowledge systems - mātauranga Māori and western science - worked alongside each other, with learning going both ways, says Tumai Cassidy from Te Rūnanga o Ōtākou. He was excited to learn from Ngātiwai tohunga Hori Parata and his son Te Kaurinui who answered Te Rūnanga o Ōtākou's call to assist with the dissection. The whale was named Ōnumia by the rūnanga, after the te reo Māori name for the native reserve stretch of coastline it was found on. The whale's skeleton has been gifted to Tūhura Otago Museum, but it will be a while before it will go on display. Right now, the bones are in Lyttelton in the care of Judith Streat. Three months in bacteria-filled baths have stripped the bones of flesh, but there is a lot of oil in deep-diving whales, so the process will take several more years. Tumai Cassidy from Te Rūnanga o Ōtākou says the whale was found on their native reserve land on the Taieri. Photo: RNZ / Tess Brunton The kauae, or jawbone, will stay with Te Rūnanga o Ōtākou, says Rachel Wesley. "Being able to claim the kauae, you know, as mana whenua, under our rakatirataka and in line with old practices from the past has been a huge step forward from what our hapū has been able to do in the past." A 3D-printed version of the jawbone will complete the skeleton in the museum. Sign up to the Our Changing World monthly newsletter for episode backstories, science analysis and more.
RNZ News
30-04-2025
- Science
- RNZ News
Our Changing World: Fiordland's underwater world
[picture id="4K88JHC_Prof_James_Bell_diving_to_photograph_Fiordland_black_coral_Credit_Matteo_Collina_jpg" crop="16x10" layout="thumbnail"] Photo: Matteo Collina Follow Our Changing World on Apple , Spotify , iHeartRadio or wherever you listen to your podcasts The lights of the remotely operated vehicle, or ROV, scan the cliff-like reef of Doubtful Sound, illuminating coloured blobs, cup-shaped sponges and branched corals hidden in the gloom. Aboard DOC's research vessel Southern Winds , Professor James Bell of Victoria University of Wellington is hunkered over the controls, in full concentration mode. Out of the darkness, a large tree-like black coral appears. Misleadingly named, these corals have black or brown skeletons with bright white feathers erupting off their branches. These white filamentous structures are the coral's polyps. This coral is a few metres across and likely many years old, as they are very slow growing. Some dead branches are adorned with colourful sponges and sea squirts (ascidians). Fishes dart and school among the coral's 'foliage'. The ROV is used to take footage of corals at depth. Photo: James Bell Providing habitat is one of the key ecosystem roles of these black corals, says James. "They are like little oases of life and biodiversity." This is one reason why he and his team are studying these strange organisms. Typically, black corals live in much deeper parts of the ocean around Aotearoa. However, Fiordland's unique ecosystem means they are found in the sounds at much shallower depths. Fiordland's abundant rainfall sweeps through the rich leaf litter of the steep forest-clad slopes, collecting tannins - a type of chemical found in woody plants and wine. This tannin stains the freshwater brown like tea, and once it reaches the fiord, it forms a layer on top of the denser seawater, essentially blocking out some of the light. Doubtful Sound. Photo: Claire Concannon / RNZ In these medium-light conditions, seaweed struggles to grow and instead there are 'animal-dominated' reefs. The steep rocky sides of the fiords are littered with slow-growing filter-feeding creatures including sponges, black and red corals, sea pens, sea fans, and sea squirts. Since 2018, a team led by James has been documenting the habitat of the outer, middle and inner areas of some fiords. The work, contracted by DOC, aims to discover what lives there, and how things are changing over time. Down to 25 metres depth is the domain of divers equipped with cameras. They take a series of photographs along the reef that are later analysed to identify the species and figure out how much of the area they are covering. For deeper spots, down to 200 metres, the researchers use the ROV. The team use an ROV to survey deeper habitats. Photo: Matteo Collina And on this trip to Doubtful Sound, PhD candidate Miriam Pierotti is also taking samples of black corals from different areas, for her research into coral resilience. Dry suits are the gear of choice in Fiordland. After donning merino layers, and pushing the air out of her sealed suit, Miriam grabs some plastic baggies and bright yellow labels. With her dive partner, Eva Ramey, she uses the labels to mark corals she is sampling - snipping a 'branch' from the large structures to place in a bag. Black corals are protected under the Wildlife Act, but Miriam has a permit to do this work. Miriam Pierotti, Matteo Collina and Dr Alice Rogers talk pre-dive. Photo: Claire Concannon / RNZ Then, she uses tinfoil to create a makeshift lab to process her samples at the back of the boat. She carefully slices small fragments of each coral sample and stores them in vials for future genetic analysis. While Miriam works, the next dive team has gone below. Matteo Collina and Dr Alice Rogers take hundreds of pictures of the marked corals, and precise GPS markings. By stitching together the photos they can recreate a 3D model of the black corals as they appear on the reef - a process called photogrammetry. Miriam Pierotti processes coral samples onboard. Photo: Claire Concannon / RNZ By combining the genetic analysis and the photogrammetry, Miriam hopes to recreate a 'family tree' of the corals. This will help her understand how the next generations are faring and how far coral larvae could be travelling within the fiords. Both are important for understanding how resilient the black corals might be to local disruptions, like landslides. Another potential disruption of interest is ocean warming. By taking live black coral samples back to the Victoria University of Wellington Coastal Ecology Lab, PhD candidate Amber Kirk is investigating how they respond when the temperature is ramped up. In 2022, a long-lasting marine heatwave resulted in sea temperatures 4.5C above average for the sounds. This team documented [ mass sponge bleaching events] as a result, and some subsequent sponge death. But it's unclear how the black coral coped. Amber Kirk monitors the black corals in the lab. Photo: James Bell In the lab, when Amber ramped up the heat to the same temperatures experienced in that heatwave, some of the corals died, but others hung on. She's now investigating how the black corals responded physiologically, and whether the microbes associated with them have changed - something they have observed in certain sponge species in response to heat. Sign up to the Our Changing World monthly newsletter for episode backstories, science analysis and more.
