Thousands of dead sardines are washing ashore in Buffalo City and along the Wild Coast as a mass die-off that reached the Eastern Cape last week spreads further east along SA’s coastline.
The latest reports follow thousands of sardines washing ashore around Gqeberha last week and earlier mass fish deaths along the Western Cape coast.
Dead sardines have been reported on KuGompo City beaches as well as in Kwelera, Queensbury and Bulugha bays and along parts of the Wild Coast, with experts warning of thousands more offshore.
Barbara Briceland, organiser of the Spring swim on Tuesday at 6.20am, on Monday said Nahoon Beach had been reopened.
“Whether you decide to dip or not, please still join us on the beach to celebrate the first day of spring. Let’s get our toes wet, walk along the beach, and watch the sun rise.
“Kevin Cole, principal natural scientist at the EL Museum, will be on the beach and speak briefly about the sardine deaths.
“We will still be collecting [cash or pet food] for Pet Pals.
“This event is for the animals and the environment. This is why we turn out. We are a resilient and adventurous lot.
“Risk is omnipresent. Everyone accepts their own.
She told Dispatch “swimmers wearing electrical shark pods will form a semi-circle in the shallows ... We are a resilient and adventurous lot! See you there.”
Local surfing guru and Dispatch columnist Nick Pike said he had seen hundreds of dead sardines in Kwelera Bay, with the fish appearing to be spreading farther along the Wild Coast.
Nelson Mandela University ichthyologist Prof Nadine Strydom said the true scale of the die-off could be far greater than the numbers visible along the coastline.
“What we see on the beach is only a fraction, as some could be lying on the seabed,” she said.
The arrival of large numbers of dead and dying fish has also raised concerns that scavenging predators could be drawn closer to shore.
Two surfers spotted a shark close to the shoreline at Nahoon Beach on Monday morning, with the shark reportedly tailing one of them before becoming stalled by a gulley.
City lifeguard Andrew Mills subsequently closed the beach as a precaution.
Local environmentalist Kevin Cole warned that the abundance of dead and dying sardines could attract sharks closer to shore.
“Reports coming in of lots more sardines still washing ashore along the coast, may bring predators like sharks closer inshore, so I think an extra bit of vigilance should be exercised,” he said.
Strydom said scavenging on dying animals was normal behaviour for many shark species.
“This would be a natural shark response,” she said.
However, WESSA Eastern Cape chair Gary Koekemoer said there did not appear to be reports of increased shark activity in other affected areas.
Scientists investigating the fish deaths say pilchard herpesvirus (PHV), previously linked to devastating sardine die-offs in other parts of the world, is the leading explanation, though the cause has not yet been conclusively established.
Researchers from Nelson Mandela University’s Institute for Coastal and Marine Research (CMR) are assisting the department of forestry, fisheries and environment (DFFE) with the investigation.
“A viral infection has been identified.
“Analyses of collected samples indicate that the sardine mortalities are associated with infection by a herpes virus, which affects the gills and makes it difficult for fish to obtain sufficient oxygen,” the CMR said.
Strydom said: “PHV is highly likely as the cause of the current large-scale mortality events.”
However, DFFE spokesperson Zolile Nqayi said detecting PHV did not prove the virus had caused the deaths.
Scientists are investigating whether it is the primary cause or is infecting fish already weakened by environmental stress.
The virus was confirmed in South African waters for the first time in July after sardines collected off Saldanha Bay, Cape Canyon, Elands Bay and Gansbaai tested positive.
“This is the first time it has happened in South African history,” Strydom said.
“Similar genetic lineage to the causative virus that affected the Australian mass mortality events in the late 1990s is suggestive of a single population origin for the virus,” Strydom said.
WWF South Africa senior technical specialist Craig Smith said the organisation was working with the government and the fishing industry.
“We are deeply concerned,” Smith said. “In Australia, the virus wiped out 70% of the stock. We fear this may be the first wave, with the possibility of a more deadly second wave.”
Scientists are also investigating environmental explanations including water temperature, algal blooms, pollution and low oxygen.
“If a large-scale or localised environmental or pollution event was the driver, other species would also be affected.
“This has not been the case,” Strydom said.
Research into previous PHV outbreaks indicates the virus is highly host-specific, with no other fish species reported affected during the massive Australian pilchard die-offs.
The greater threat to other marine species is the loss of a food source.
“Pelagic fish such as sardines sit at the start of the food chain and so their loss will impact all other species dependent on them, for example African penguins, Cape gannets, dolphins and others,” Koekemoer said.
“For the African penguin that is critically endangered and on the verge of extinction, this comes as a massive blow, potentially.”
How the virus may have entered South African waters remains unknown.
“There are thousands of fish still dead in the area, there will be more numbers of them washing up,” Cole said.
“We can expect a huge widespread number of them washing up in the upcoming days, depending on the weather conditions.”
The die-off could also have consequences for tourism and fishing.
“Our coastline is the pathway for the sardine run, one of the largest biomass migrations in the world,” Koekemoer said.
“So tourism may also be impacted and pelagic commercial/small-scale fishing too.”
Strydom warned recovery could be lengthy.
“It may take many years for the pilchard population to recover,” she said.
An intergovernment task team is co-ordinating surveillance, testing, disposal of dead fish and assessments of the impact on sardine stocks, while the Small Pelagic Scientific Working Group is due to meet this week to consider whether additional management measures are warranted.
The die-off has already had wider consequences.
At the Koeberg nuclear power station near Cape Town, dead sardines clogged a cooling-water intake basin, forcing the national electricity utility to halve power output at one of its two units.
PHV poses no known danger to humans, but experts have warned people not to collect, handle or eat dead sardines because decomposing fish can harbour harmful bacteria.
Fishermen are also warned against collecting dead or dying sardines for bait.
“This could reintroduce the virus again into our waters at a later date, resulting in another wave of infection,” said Strydom.
Researchers are continuing to monitor the die-off and its potential long-term consequences. ― Additional reporting by AFP
Daily Dispatch
