Cetacean Strandings Investigation Programme- UK strandings

09/07/2026

Really pleased to hear the news that lead CSIP researcher Dr Rosie Williams has been awarded a significant Natural England Programme grant to investigate and other contaminants of emerging concern in harbour porpoises and common dolphins that we've examined. Working with Cefas ZSL and Natural England colleagues alongside CSIP partners, we hope this will help shed more light on these pollutants and the impacts on our vulnerable marine species.

02/07/2026

A CSIP team from ZSL recovered the body of an adult male short-beaked common dolphin from the Thames earlier today. This is believed to be a common dolphin that had been sighted at various locations across the Thames over the last few days. Unfortunately, it live stranded and died at Mortlake earlier this morning- a examination will be carried out soon to try to learn more about the dolphin and possible causes of its live stranding. This is an unusual stranding for the region- common dolphin strandings have been rarely reported within the southern North Sea over the last 35 years since the inception of the CSIP in 1990. However, they have been increasingly recorded in the region in recent years, potentially due to climate change driven shifts in distribution- the last strandings recorded in the Thames were a pair of individuals in August 2024.

Many thanks to our friends at British Divers Marine Life Rescue (Thames chapter) and to the team at Tideway Scullers School for all their help with the recovery.

29/05/2026

Many thanks to our colleagues at Marine Environmental Monitoring for attending the site of this unfortunate bycatch event over the bank holiday weekend. Large numbers of tope and other shark species were found entangled in nets that washed up at Pembrey country park in Carmarthenshire on 24th May- likely accidentally caught and the gear subsequently lost. Thanks to MEM's efforts, several sharks were recovered for necropsy and sampling later this year, as part of CSIP's remit to investigate some stranded elasmobranch species. Hopefully the samples and data we will collect alongside ZSL partners will help support ongoing research on both sharks and bycatch, so we can at least learn something from this unfortunate event.

Images credit Pauline Morris and MEM.

25/02/2026

The CSIP attended a highly unusual stranding yesterday. A CSIP team from ZSL accessed and examined a 3.6m male s***m whale calf that was reported stranded at Challaborough Bay in southwest Devon on 21st February. A small decomposed s***m whale was also reported in southeast Cornwall earlier this month but could not be accessed for examination. Photos taken at the time allowed us to make a match between the two stranding events to demonstrate they were the same individual.

Although the whale was in a decomposed condition, we were able to conduct a basic field necropsy and sampling exercise. A small quantity of sand/beach material was found within the stomach chambers- this was likely actively ingested, suggesting that the whale may have live stranded at or around the time of death. A wide range of samples were also collected that may help inform future research in areas such as contaminant exposure and population structure.

Notwithstanding that the whale was initially reported in southeast Cornwall, this is the first stranding of a s***m whale recorded in Devon since strandings began to be routinely recorded in the UK nearly 120 years ago. It’s also the smallest and youngest s***m whale ever recorded in England and Wales over this same period. Historically, nearly all s***m whale strandings in the UK have been subadult males around 10-14m long, reflecting our proximity to the normal distribution of s***m whale ‘bachelor pods’. Female s***m whales and their young aggregate in ‘matriarchal pods’ in warmer waters much further south.

Birth length of s***m whales is quoted as around 3.5m, so this was an exceptionally young individual and given the condition of the body, likely died some distance south of us, with the body drifting northwards and making landfall on our shores due to the recent period of intense storm activity the UK has been experiencing.

Huge thanks to our friends at Coral Smith and the volunteers at the Devon Wildlife Trust Marine Strandings Network for all their help yesterday- and many thanks to Abbie and the team at Challaborough Bay Holiday Park for helping facilitate the onsite examination. Many thanks also to our friends at the Cornwall Wildlife Trust Marine Strandings Network for sharing images of the stranding in SE Cornwall which enabled us to make comparisons.

12/02/2026

We're really pleased to see this paper "Traumatic injuries by grey seals on delphinids from northwest European waters" published in the journal Diseases of Aquatic Organisms today. Led by our friends at Faculteit Diergeneeskunde in Utrecht University and with involvement from CSIP coauthors from ZSL and the Cornwall Marine Pathology Team, this is the first evidence of grey seal interaction with a number of dolphin species across the region. The study is based on postmortem examinations of four stranded dolphins from the Netherlands and the UK. All animals had injuries consistent with grey seal bites, confirmed by pathological and microbiological examination. Although none of the dolphins studied died directly from an attack, the wounds and the bacteria found indicate that grey seals also interact with a variety of dolphin species- until now, such interactions were almost exclusively known to occur in harbour porpoises. This study between Dutch and UK partners highlights the value of collaboration between stranding networks across the North Sea region.

https://www.int-res.com/abstracts/dao/v165/dao03898?tx_intres%5BfromSearch%5D=1&cHash=a65f390881b798a8aa9d75997d2a5539

Grijze zeehonden bijten niet alleen bruinvissen: nieuw onderzoek toont eerste schade bij dolfijnen 🐬

Onderzoekers van de Universiteit Utrecht en partners uit het Verenigd Koninkrijk (o.a. ZSL) hebben voor het eerst aanwijzingen gevonden dat grijze zeehonden ook dolfijnensoorten kunnen verwonden. Tot nu toe waren dergelijke interacties vrijwel uitsluitend bekend bij bruinvissen. De studie, vandaag gepubliceerd in het wetenschappelijke tijdschrift Diseases of Aquatic Organisms, toont aan dat grijze zeehonden een bredere impact kunnen hebben op kleine walvisachtigen in de Noordzee dan eerder gedacht.

Hoewel geen van de onderzochte dolfijnen direct stierf aan een aanval, wijzen de wonden en de gevonden bacteriën erop dat grijze zeehonden ook interacties hebben met andere tandwalvissen dan bruinvissen. Dit suggereert dat zeehonden als toproofdieren een grotere en meer diverse rol spelen in het Noordzee-ecosysteem.

De verwondingen bleken vaak enkele dagen tot weken oud, wat erop wijst dat de dieren de ontmoeting overleefden maar later stierven aan ernstige bacteriële infecties, waaronder bacteriesoorten die specifiek voorkomen bij zeehonden. Dit maakt de gevallen extra relevant voor het begrijpen van ziekteverspreiding tussen mariene zoogdieren.

Volgens de onderzoekers moet bij toekomstige autopsies op dolfijnen vaker worden gekeken naar mogelijke interacties met grijze zeehonden. Hoofdonderzoeker Lonneke IJsseldijk: “Onze bevindingen laten zien hoe waardevol goed gecoördineerd strandingsonderzoek is. Door informatie uit verschillende landen te bundelen, krijgen we een scherper beeld van wat er in de Noordzee gebeurt."

👉 Lees het nieuwsbericht op onze website: https://www.uu.nl/nieuws/grijze-zeehonden-bijten-niet-alleen-bruinvissen-nieuw-onderzoek-toont-eerste-schade-bij-dolfijnen

29/01/2026

Really busy start to 2026 on the strandings front- 27 stranded cetaceans, seals and marine turtles recovered by the team around the coast of England and Wales so far this year, Goretti, Ingrid and Chandra have kept us all busy... The ZSL CSIP are on the way to Northumberland to try to access and examine this stranded white-beaked dolphin later today, we'll post more information on other recent strandings when we're back at base. Huge thanks to everyone who has been helping us out over the last few weeks!

20/01/2026

On this day 20 years ago…

On 20th January 2006, one of the highest profile stranding events ever recorded occurred within the river Thames in London. The first sightings of a whale swimming within the Thames were reported by public on 19th January, with the whale later identified as a northern bottlenose whale, a deep diving species which shouldn’t normally be found anywhere near London.

Over the course of the next two days a large scale rescue attempt was mounted by our friends at British Divers Marine Life Rescue and the Port of London Authority, with veterinary support and advice provided by a CSIP team from ZSL. Although the rescue attempt ultimately didn’t succeed and the whale sadly died during the translocation out of the Thames, the response of Londoners and what felt like much of the world that day was profoundly moving for everyone involved. Stranding events like these are markedly unusual and likely once in a lifetime occurrences for most of us. But we all learnt a huge amount from both the rescue attempt and the subsequent necropsy, helping us to shape both future responses to live strandings of deep diving species and helping to inform research here in the UK and internationally.

Many thanks once again to everyone involved over those days in January, twenty years ago...

03/01/2026

A CSIP team from ZSL recovered two porpoises yesterday- both live stranded within a few miles of each other on the north Kent coast last week. Both on thin side, interesting wounds (and lots of whale lice) on the younger porpoise... examinations to follow next week where we hope to learn more- many thanks to our British Divers Marine Life Rescue friends for their help!

31/12/2025

Happy New Year! Huge thanks again to everyone who's helped us out over the last year, see you back on the beaches soon in 2026...

13/10/2025

Tickets still available to the CSIP convened ZSL Science and Conservation Events free public event at ZSL this Wednesday evening. Join us in person or online to hear presentations from a great line up, on the impacts of marine chemical, acoustic and physical pollution. More information on some of the featured CSIP cases and papers and research they have helped inform available here 👇

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