80 Dead Sharks Wash Ashore in Belgium; Bycatch Likely Cause
More than 80 starry smooth-hound sharks have washed ashore on the coast of Koksijde, a Belgian coastal town in West Flanders, since Thursday 28 May, prompting an investigation by marine researchers who suspect the animals died as bycatch from commercial fishing vessels.
The carcasses, measuring between 75 centimetres and one metre in length, have been appearing on the beaches between Sint-Idesbald and Ster der Zee, with two additional specimens found in neighbouring De Panne. The majority are pregnant females, according to researcher Joanna Desmidt of the Institute for Agriculture, Fisheries and Food Research (ILVO).
The Scale of the Stranding
Local environmental officer Edwig Dolfen has been coordinating the collection effort. “Friday we collected 26 specimens, Saturday there were 17 more, and Sunday there were 37,” Dolfen told De Morgen. On Monday, three more were collected, bringing the total above 80.
The first six sharks were spotted by a beach walker on Thursday evening. By Friday morning, the tally had risen to 24, with marine biologist Jan Haelters of the Royal Belgian Institute of Natural Sciences (KBIN) joining the investigation. The numbers continued climbing through the weekend.
Two Possible Explanations
Desmidt has proposed two hypotheses for the mass mortality. The primary explanation is bycatch: the sharks were caught in fishing nets, died, and were discarded overboard. EU regulations permit fishermen to throw dead smooth-hounds back into the sea because the species has no commercial quota and no market in Belgium or the Netherlands.
“The sharks were probably discarded as bycatch from fishing,” Desmidt told VRT NWS. “That also happened last weekend in Wales, where smooth-hound sharks washed ashore as well.”
A secondary hypothesis suggests the pregnant females may have succumbed to oxygen deprivation while swimming in warm, shallow coastal waters en route to a breeding ground — what Desmidt describes as a “maternity clinic” — in the Schelde Delta region of the Netherlands.
Desmidt believes both factors may be at play, creating a “perfect storm” for mass mortality. The sharks showed no external bite marks, ruling out seal predation, but some displayed internal injuries consistent with net capture.
A Vulnerable Species
The starry smooth-hound (Mustelus asterias), known in Dutch as the gevlekte gladde haai, is classified as “Vulnerable” on the IUCN Red List and listed as “sensitive” on the Dutch Red List. The species is ovoviviparous, giving birth to live pups, and pregnant females migrate to warmer coastal waters in late spring and early summer to give birth.
Despite being edible, the species has no commercial value in Belgian or Dutch markets due to lack of consumer demand. “If sharks were sold in stores, they probably wouldn’t be ordered often,” Desmidt explained. “That’s why this species is not popular with fishermen. They derive no economic benefit from it.”
Scientific Investigation Underway
Seven well-preserved specimens are being examined for external and internal injuries, toxins, and parasites as part of the ELASMON project, a research initiative running from September 2024 to August 2027 that aims to improve monitoring and protection of sharks and rays in the Belgian North Sea.
“Such a mass is always exceptional, but the number could still rise,” Desmidt said. “There are no protocols for when so many sharks wash ashore. For us, it’s also a matter of weighing how to get the most out of this research.”
A Broader Pattern
The Koksijde stranding follows a similar event just days earlier in Wales, where hundreds of dead dogfish and other marine life washed up on Pembrey Beach in Carmarthenshire and Saundersfoot in Pembrokeshire. The Guardian reported that local conservationist Cliff Benson of Sea Trust Wales said the incident likely involved a fishing boat discarding unwanted catch. BBC News confirmed that Natural Resources Wales investigated and found the fish “appear to be dogfish, and this is likely linked to fishing by-catch being discarded at sea.”
A similar mass stranding of starry smooth-hounds also occurred on the same Belgian coast in May 2022, suggesting a recurring phenomenon.
Policy and Conservation Implications
The event highlights tensions between EU fisheries regulations — which allow discarding of non-commercial species — and marine conservation goals. Researchers hope the stranding will provide valuable data for the ELASMON project, potentially helping to identify and protect critical nursery areas for the species in the North Sea.
“If we can map that nursery area, then we can protect it,” Desmidt said. The coming laboratory analysis of the preserved specimens may determine whether death was primarily due to net trauma, oxygen deprivation, or a combination of factors, and could inform future policy discussions on bycatch regulations for non-commercial shark species.
As the investigation continues, local authorities are monitoring the beaches daily. Desmidt cautioned that more sharks could still wash ashore in the coming days.