The rare discovery of a female Greenland shark in Cornwall a month ago has now led to a diagnosis of meningitis as the reason for what was probably a live-stranding – and the first evidence of the infection in the world’s longest-living vertebrate.
The 4m female shark happened to be spotted by a Zoological Society of London (ZSL) biologist walking her dog on a beach near Penzance on 13 March, but before it could be collected for examination it was washed back into the sea.
Two days later its carcass was seen floating off Newlyn from a tour boat, and was recovered by Cornwall Wildlife Trust Marine Strandings Network volunteers.
Greenland sharks (Somniosus microcephalus) live in Arctic and north Atlantic waters as deep as 2.6km, but the meningitis diagnosis could explain why this one had strayed so far from its natural environment.
Infection of its brain by the Pasteurella bacterium is thought to have caused the disease and led to the shark’s early demise. Greenland sharks can live for more than 400 years, and females are not considered to reach maturity until around 150 – making this one a century-old juvenile.
The post mortem was conducted by the Cornwall Marine Pathology Team, part of the ZSL’s Cetacean Stranding Investigation Programme (CSIP).
“The shark’s body was in poor condition and there were signs of haemorrhage within the soft tissue around the pectoral fins which, coupled with the silt found in her stomach, suggested she may well have live-stranded,” said team pathologist James Barnett.
“As far as we’re aware, this is one of the first post mortem examinations here in the UK of a Greenland shark, and the first account of meningitis in this species.”
“This unfortunate and extraordinary stranding has allowed us to get an insight into the life and death of a species we know little about,” said CSIP project lead Rob Deaville.
“Ultimately, like most marine life, deep-sea species such as Greenland sharks may also be impacted by human pressures on the ocean, but there is not enough evidence at this stage to make any connections.” The species is IUCN-listed as Vulnerable.
Launched in 1990, CSIP co-ordinates investigations of all cetacean, marine turtle and basking shark strandings around the UK – more than 17,000 to date – and combined with almost 4,500 post mortems has assembled one of the world’s biggest research datasets on strandings and causes of mortality. Divers should note its hotline number for sightings, 0800 652 0333.