Marine experts are concerned about the condition of Cape fur seals as carcasses continue to wash up along the SA coast.

Government is yet to determine the cause of the widespread seal die-off that extends from at least Lambert's Bay on the West Coast to Hermanus in the southern Cape.

Several thousand animals have died over the past three months, though the exact number is unclear and organisations are pulling together to collect valuable information. The deaths coincide with a normal annual spike in pup and yearling deaths linked to the seal breeding cycle, but this year the mortality rate is much higher and includes many sub-adult and adult seals. The start of the die-off also coincided with an avian flu outbreak that killed thousands of seabirds.

Though government remains tight-lipped about its seal post-mortem results, some experts have urged the public to report seal deaths and to be cautious about handling carcasses, particularly during the holiday period with more people at the coast. Initial lab tests, as yet unconfirmed, suggest the deaths could be similar to other historic die-offs that have been linked to toxic sea life, similar to that which affects shellfish during “red tide”.

“My opinion is that this appears to be a pathogen/toxin, in conjunction with some animals being malnourished,” said veterinarian Brett Gardner, who has researched seal infections in Australia and Namibia.

“The typical lesions are in the lungs and brain, so together with the seizures it narrows the list of causes down,” Gardner said, adding that there were multiple pathogens that could cause mass mortality, all of which needed to be investigated.

Stellenbosch University marine scientist Dr Tess Gridley said the delay in a formal diagnosis was due to the detailed and difficult analysis required, involving post mortems on only the freshest animals and brain sample analysis.

“It is not just a case of looking at the animal ... Really detailed investigation is required,” Gridley said. “As this is also the breeding time, access to the colonies is restricted, making it difficult to assess the situation more thoroughly in the busiest seal areas.”

She urged the public not to approach sick seals or seemingly abandoned pups, but rather to report these to the SPCA or Hout Bay Seal Rescue Centre.

In November the Western Cape government also urged the public to stay away from dead seals.

“The testing is taking a while longer than previously expected,” the provincial environmental affairs department said.

Reports of dead seals continued this week, including from the West Coast National Park, where hundreds of carcasses washed up on well-known 16 Mile Beach.

“Today I came across one of the most devastating sights I have ever seen,” said one post on the Community Clean-Up Initiative WhatsApp group.

“As soon as I started walking along the beach my insides turned upside down. Apart from the immeasurable amount of rubbish just everywhere (and this is a National Park), I was greeted by a sight I was not prepared for — hundreds of dead seals strewn along a very long stretch of beach.”

Similar scenes have been reported from other coastal areas over the past few months.

Gregg Oelofse, Cape Town's marine manager, said the city was assisting with carcass counting.

Fortunately there is also some good news for ocean enthusiasts: white sharks have been spotted in False Bay, after a lengthy absence from one of their historic hunting grounds.

The Shark Spotters Safety Education Research Conservation in Cape Town issued a warning earlier this month after four great white and bronze whaler sharks were spotted off Cape beaches. Pictures of great whites visiting ski boats have also circulated on social media, prompting numerous comments.

“This is good news for our marine ecosystem,” said Liza Weschta.

“It would be wonderful to witness their return,” agreed Sue Rosenberg.

However, a few sightings should not obscure the bigger picture of a steady decline in SA’s white shark population, possibly due to anthropogenic activities, according to Dr Sara Andreotti, a marine biologist affiliated to Stellenbosch University’s Department of Botany and Zoology.

“The population decline and the potential crash of white sharks in South Africa don't mean that we won't still have sporadic sightings of a few individuals,” Andreotti said.

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