Cochimicetus convexus: A new species of Eomysticetid Whale from the Late Oligocene of Baja California Sur, Mexico.

Baleen Whales, Mysticetes, are the largest Animals alive today, and, as far as we can tell, the largest Animals ever to have lived. They are able to achieve this huge size by a unique feeding mechanism; using a system of keratinaceous baleen plates  to filter food items (such as Crustaceans of small Fish) from the water. The largest Baleen Whales are lunge feeders, capable of engulfing whole shoals of prey-items, then  trapping them on the baleen plates as the accompanying water is pushed out through. The earliest Mysticetes appeared in the Late Eocene, though these were still Toothed Whales, little different from the ancestors of today's Odontocetes. The first true Baleen Whales were the Eomysticetids, a group which appeared in the Early Oligocene. Eomysticetids had baleen plates similar to those of modern Baleen Whales, but appear to have lacked the ability to lunge-feed in the same way, and were not capable of reaching the same sizes.

In a paper published in the journal Palaeontologica  Electronica in January 2025, Cielo Cedillo-Avila and Gerardo González-Barba of the Museo de Historia Natural at the Universidad Autónoma de Baja California Sur,  and Azucena Solis-Añorve, also of the  Museo de Historia Natural, and of Posgrado of Ciencias Marinas and Costeras at the Universidad Autónoma de Baja California Sur, describe a new species of Eomysticetid Whale from the Late Oligocene San Gregorio Formation of Baja California Sur.

The new species is described from a single specimen comprisng a partially complete skull with a length of 147 cm, along with both mandibles and tympanic bulla. It is named Cochimicetus convexus, where 'Cochimicetus' refers to the indigenous Cochimi people, a nomadic group who once inhabited the northern part of Baja California Sur, and 'convexus' refers to the convex shape of the anterior tip of the tympanic bulla, which tends to be pointed in other Eomysticetid Whales.

Dorsal view of the holotype of Cochimicetus convexus. (A) Image showing the identified structures. (B) photography with scale 10 cm. Cedillo-Avila et al. (2025).

Cochimicetus convexus is the fourth species of Eomysticetid Whale from the Oligocene of Baja California Sur, demonstrating the importance of the area for our understanding of the early evolution of the Mysticetes. 

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Orcaella brevirostris: Irrawaddy River Dolphin extinct in Laos, less than 90 surviving in Cambodia.

The Irrawaddy River Dolphin, Orcaella brevirostris, is now officially extinct in Laos after the last surviving member of the species inhabiting a trans-border pool shared with Cambodia, died in February this year. The Dolphin, a male identified as ID#35, was found on a shore of the Chheuteal Pool in Stung Treng Province, Cambodia, having apparently died of injuries sustained when he became entangled in fishing nets on the Laos side of the pool. Irrawaddy River Dolphins are (or were) officially protected in both Laos and Cambodia, with a ban on gill nets, which are notoriously dangerous to small Cetaceans, in environments where they are found. However, while this rule was enforced on the Cambodian side of the border, where there are patrols by river guards and a public education program, part of Chheuteal Pool lies within Laos, where the rules were not enforced, and where Cambodian river guards are unable to operate.

 

ID#35, the last Irrawaddy River Dolphin living in the Chheuteal Pool spanning the border between Laos and Cambodia, found dead in February 2022. Phnom Penh Post.

In 1993 there were 17 Irrawaddy River Dolphins living in Chheuteal Pool, by 2009 this number had fallen to seven, by 2012 there were only six, in 2018 three Dolphins were recorded, and since 2021 ID#35 had been on his own. The Dolphin had been visibly unwell since becoming entangled in fishing gear in January, and was about half of his normal bodyweight when he died. Officials from the Cambodian Fisheries Administration and WWF Cambodia had considered moving him to a site lower in the Mekong Valley in Cambodia, where there is another population, but concluded that they lacked the expertise to do so. 

 

An Irrawaddy River Dolphin, Orcaella brevirostris, in a deep-water pool in Cambodia. Lor Kimsan/WWF Cambodia.

The Mekong Valley population in Cambodia is now thought to comprise only 89 individual Dolphins, with few other populations, in the Irrawaddy River in Myanmar, the Mahakam River in Indonesian Borneo, in Chilika Lagoon in India, in Malampaya Sound in the Philippines, and on the Trat coast in Thailand, each now thought to be less than 100 individuals, although a much larger population is present in the Sundarbans Mangrove Forest of Bangladesh, possibly numbering as many as 6000 individuals. The species is currently classified as Endangered under the terms of the International Union for the Conservation of Nature's Red List of Threatened Species. 

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Sperm Whales stranded on Yorkshire coast all reported to have died.

A pod of ten young Sperm Whales, Physeter macrocephalus, which stranded on the coast of East Yorkshire between Tunstall and Withernsea have all died, according to British Divers Marine Life Rescue. The Whales were first spotted by a member of the public at about 8.30 am, who reported them to the Maritime and Coastguard Agency, who in turn contacted British Divers Marine Life Rescue. It was not considered possible to mount any form of rescue operation for the Whales, due to their large size (Sperm Whales can reach about 20 m in length, and weigh up to 80 tonnes) and the rough seas in the area. Sperm Whales seldom live for long if they strand on the shore, and initial inspections of the Yorkshire Whales suggested that they appear to have been malnourished before stranding. Reports of additional Whale strandings at Spurn Point have not been substantiated.

 

A Sperm Whale, Physeter macrocephalus, stranded on the coast of East Yorkshire on 24 December 2020. British Divers Marine Life Rescue.

Sperm Whales are the largest species of Toothed Whales, reaching about 20.5 m in length. The species is currently considered to be Vulnerable under the terms of the International Union for the Conservation of Nature's Red List of Threatened Species, with a population that probably measures somewhere in the hundreds of thousands. The species is thought to have had a population of over a million around the beginning of the nineteenth century, but to have fallen to about 29 000 by 1880. The population rose again in the early twentieth century, as targeting of the species by Whalers declined, then fell from 1946 to 1980 as hunting of Sperm Whales increased again. Since 1985 the species has been protected by a moratorium on the taking of Whales agreed by the International Whaling Commission, and although a few Sperm Whales have been taken by the Japanese Whaling fleet since this time, the main threat to these animals is thought to come from Fishing nets, in which they can become entangled and drown, and plastics, which they can ingest, filling up their stomachs and preventing them from taking their normal food (mostly Squid). 

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About 120 Short-finned Pilot Whales returned to the sea following mass stranding in Sri Lanka.

About 120 Short-finned Pilot Whales, Globicephala macrorhynchus, have been returned to the sea, following a mass stranding event. The Whales began to wash up on a beach near Panadura, on the southwest coast about 25 km to the south of the capital, Colombia, on Monday 2 November 2020. Volunteers from the local community, joined by members of the country's Navy and Coast Guard, immediately began work to return the Whales to the sea, with most of the Animals thought to have been returned safely, although at least four have known to have died.

 

A Short-finned Pilot Whale, Globicephala macrorhynchus, that died following a mass stranding event in Sri Lanka on 4 November 2020, one of four Whales known to have died as a result of the incident. Lakruwan Wanniarachchi/AFP/Getty Images.

Short-finned Pilot Whales, Globicephala macrorhynchus, are considered to be of Least Concern under the terms of the International Union for the Conservation of Nature's Red List of Threatened Species, with a global population of over 700 000 individuals, split into four distinctive populations, two in the Pacific and one each in the Indian and Atlantic oceans. They typically live in pods of eight to ten individuals, but sometimes assemble into larger groups, sometimes with many hundreds of individuals congregating at the same location. However, this behaviour can make these Whales vulnerable to mass strandings, if large gatherings become spooked or disorientated by some event. The actual causes of such strandings are unclear, with a variety of causes having been suggested, including naval sonar, soar activity, and anomalies in the Earth's geomagnetic field.

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Whale dies after stranding on Edinburgh beach.

A Whale has died after stranding on a beach in Edinburgh, Scotland. The Whale, identified as a young Sowerby’s Beaked Whale, Mesoplodon bidens, was found on a beach near the mouth of Brunstane Burn on the afternoon of Tuesday 13 October 2020, while still alive, but died shortly thereafter, despite attempts by volunteers from the Scottish Society for the Protection of Animals and British Divers Marine Life Rescue to refloat it. 

 

A Young Sowerby’s Beaked Whale, Mesoplodon bidens, stranded on an Edinburgh beach on 13 October 2020. Lyn Murray/Daily Record.

Sowerby's Beaked Whales are found throughout the North Atlantic and North Sea, although they are reclusive Animals which tend to avoid boats and other Human objects, making them rarely seen. As such their population structure is not really known, and they are classified as Data Deficient under the terms of the International Union for the Conservation of Nature's Red List of Threatened Species. This is the third stranding of a member of the species recorded in the UK this year, with British Divers Marine Life Rescue recording two strandings in August, one in Suffolk and one in Hampshire, which implies a reasonably healthy population in UK waters (although individual strandings are sad, the fact that strandings are occurring implies that Whales are present. Sowerby's Beaked Whales are protected by the Agreement on the Conservation of Small Cetaceans of the Baltic, North East Atlantic, Irish and North Seas, the Agreement on the Conservation of Cetaceans in the Black Sea, Mediterranean Sea and Contiguous Atlantic Area, and the Memorandum of Understanding Concerning the Conservation of the Manatee and Small Cetaceans of Western Africa and Macaronesia. Historically the species was sometimes targeted by Norwegian Whalers, but this has not been the case in recent history; though these Whales are thought to be at risk from entanglement in fishing gear.

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Humpback Whale strands on beach near Cape Town, South Africa.

The body of a Humpback Whale, Megaptera novaeangliae, has been found stranded on a beach near Cape Town in South Africa. The Whale, measuring 10-12 m in length, was found on Strandfontein Beach in Western Cape Province, at about 2.00 pm local time on Saturday 10 October 2020. The National Sea Rescue Institute has warned bathers in the False Bay area to be particularly aware of Sharks in the area, as they are attracted to the scent of Whale carcasses. Humpback Whales are frequently sighted around the Western Cape between May and November, as they migrate between their Antarctic feeding grounds and the areas off the coast of Mozambique where they breed.

 

A stranded Whale on Strandfontein Beach in Western Cape Province, on 10 October 2020. Shark Spotters/Facebook.

Humpback Whales were nearly exterminated by commercial Whaling in the first part of the twentieth century. The species has been protected since 1946, and in recent years their population has appeared to be recovering in many areas, now being seen as being of Least Concern  under the terms of the International Union for the Conservation of Nature's Red List of Threatened Species. The Whales are recovering in many parts of the globe, and are starting to appear in areas where they have not previously been recorded.

Humpback Whales were nearly exterminated by commercial Whaling in the first part of the twentieth century. The species has been protected since 1946, and in recent years their population has appeared to be recovering in many areas, now being seen as being of Least Concern  under the terms of the International Union for the Conservation of Nature's Red List of Threatened Species. The Whales are recovering in many parts of the globe, and are starting to appear in areas where they have not previously been recorded.

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Scientists and conservationists call on governments to protect Whales, Dolphins, and Porpoises from the real and imminent risk of extinction.

A group of over 350 scientists and conservationists have signed an open letter raising their gravest concerns about the extinction risk to many species and populations of Cetaceans (Whales, Dolphins and Porpoises). Each of the signatories is a Cetacean specialist and each one of them believes this issue is now critical. The lack of concrete action to address threats adversely affecting Cetaceans in our increasingly busy, polluted, over-exploited and Human-dominated seas and major river systems, means that many, one after another, will likely be declared extinct within our lifetimes.

Even the large whales are not safe. The recent listing of the North Atlantic Right Whale, Eubalaena glacialis, by the International Union for Conservation of Nature as Critically Endangered reveals the serious failure of its relatively wealthy range countries to address a critical decline. Moreover, the factors driving this ongoing decline are well known, and, we believe, could be addressed. Only a few hundred North Atlantic right whale adults remain and, unless appropriate action comes soon, we will undoubtedly lose this entire species.

 

The North Atlantic Right Whale, Eubalaena glacialis, designated as Critically Endangered by the International Union for the Conservation of Nature on 1 January 2020, with an estimated surviving population of 200-250 mature individuals globally. Oceana.

Similarly, the Critically Endangered Vaquita Porpoise, Phocoena sinus, of the Gulf of California, Mexico, sits poised on the knife-edge of extinction, with an estimated population size that may be as low as only ten individuals.

 

A Vaquita Porpoise, Phocoena sinus, calf being released into the Gulf of Mexico. The species was designated as Critically Endangered by the International Union for the Conservation of Nature on 20 July 2017, when there were estimated to be eighteen surviving individuals. There are now thought to be less than ten. HO/AFP/Getty Images.

It is now almost inevitable that these two species will follow the Baiji or Chinese River Dolphin, Lipotes vexillifer, down the road to extinction. The Baiji was identified as Possibly Extinct by the International Union for the Conservation of Nature in 2017 and, regrettably, there is little hope for this species. The signatories to the letter believe, in all three cases, that enough was known about the situation of the species concerned for these dramatic declines to have been avoided, but that the political will to take action has been lacking.

 

A Baiji or Chinese River Dolphin, Lipotes vexillifer. The species was designated as Critically Endangered and Possibly Extinct by the International Union for the Conservation of Nature on 20 August 2017. The last known individual, named Qiqi (淇淇) died in 2002, with one subsequent reported possible sighting of the species in August 2007. Whale and Dolphin Conservation.

The bleak outlook for these three species shows how often too little is done too late. Of the 90 living species of cetaceans, more than half now have a concerning conservation status according to the International Union for the Conservation of Nature, with 13 species listed as Critically Endangered or Endangered, 7 as Vulnerable and 7 as Near Threatened, whilst 24 species are Data Deficient. These Data Deficient species may also be imperilled. We simply do not know. This lack of clear information about so many species and populations is itself a major concern.

Additionally, there are 32 subspecies and other distinct cetacean populations which are presently either Endangered or Critically Endangered, and with ongoing research we are recognizing more populations of Cetaceans that are discrete and require conservation action. Regrettably, as the cases of the Lahille’s Bottlenose Dolphin, Tursiops truncatus gephyreus, of the subtropical western South Atlantic, the Gulf of Corinth Common Dolphin, Delphinus delphis, and the Orcas, Orcinus orca, of the Strait of Gibraltar all illustrate, recognition of their distinctiveness may coincide with the realisation that their population is already in danger of extinction.

 

A Lahille’s Bottlenose Dolphin, Tursiops truncatus gephyreus. This subspecies was designated as Vulnerable by the International Union for the Conservation of Nature on 7 June 2019, when there were thought to be about 360 individuals surviving. Els Vermeulen/Red List.

Cetacean populations are adversely affected by many interacting factors, including chemical and noise pollution, loss of habitat and prey, climate change and ship-strikes. For many, foremost among these threats is incidental take in fishing operations.

Bearing these urgent matters in mind and with the knowledge that cetacean populations can be lost very quickly, the signatories call on countries with Cetaceans in their waters to take precautionary action to ensure these species and populations are adequately protected from human activities, including implementing appropriate and fully resourced monitoring. They note that improved monitoring technologies now offer new opportunities to observe and address activities at sea; and all nations to both work with and strengthen the relevant international bodies that seek to address threats to Cetaceans, including, but not limited to, the International Whaling Commission and the Convention for the Conservation of Migratory Species of Wild Animals, both of which are generating important conservation initiatives at this time. Foremost among other relevant international organisations are the regional fisheries bodies, which can address fishing-related threats to Cetaceans, noting the urgent need to address such impacts on many populations.

Finally, the signatories note that Cetacean conservation, like much that relates to the marine environment, may be a concern that seems remote to many people. However, as the COVID-19 pandemic has shown, our connection to nature is a key component in our own wellbeing. Whales, Dolphins and Porpoises are seen and enjoyed all over the world, and are valued as sentient, intelligent, social and inspiring species; we should not deny future generations the opportunity to experience them. They are also sentinels of the health of our seas, oceans and, in some cases, major river systems and the role of Cetaceans in maintaining productive aquatic ecosystems, which are key for our survival as well as theirs, is also becoming clearer.

The signatories ask that anyone reading the letter bring this statement to the attention of the relevant policy makers in theit country and help them to help the Cetaceans.

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