The Department of Forestry and Fisheries has warned the public not to consume dead marine species as they could be toxic. This after a large number of fish and lobster washed up at beaches along the West Coast.
Other marine animals found dead include prawns, crabs and cuttlefish, from the Berg River mouth area close to Velddrif, and mostly inside the estuary.
A number of lobsters were also discovered at the mouth of the estuary and adjacent shoreline.
The department's spokesperson, Peter Mbelengwa, said this was due to the annual red tide.
“The appearance of washed-up lobsters carries significant health risks, rendering them unsuitable for consumption. Uncertainty surrounding their time of death, coupled with potential contamination by algal toxins, poses dangers to human health.
Ingestion of these toxins can lead to severe adverse reactions and even fatalities,” said Mbelengwa.
According to the department, it collaborated with various national and local authorities to respond to the walkouts through the West Coast Rock Lobster Walkout Contingency Plan.
“This comprehensive plan involves collecting live lobsters, relocating them to areas with normal oxygen levels, and ensuring the safe disposal of deceased lobsters. Simultaneously, scientists closely monitor the red tide, document the species washed ashore, and conduct analyses, including size and sex composition.
“Large-scale lobster walkouts have profound consequences for both the marine ecosystem and local economies. Recent research by the Department’s Crustacean Research team uncovered substantial reductions in lobster densities following walkouts of 550 tons in 2022 and 100 tons in 2023, particularly impacting Elands Bay,” said Mbelengwa.
He said this decline in lobster density translated to reduced catches in subsequent seasons, exacerbating economic challenges for West Coast fishing communities heavily reliant on the lobster resource.
Red tides are large amounts of phytoplankton (single-cell algae) that were common during late summer and autumn along the West Coast, Mbelengwa explained.
“These are mostly harmless, but some are not, and therefore are referred to as harmful algal blooms or HABs. These blooms may be harmful due to their toxicity or due to their drastically reducing oxygen levels in the sea as they begin to decay. These, in turn, often result in mass mortalities of marine organisms. Possibly the best-known impact is on the West Coast rock lobster (Jasus lalandii), locally called kreef.
“Mass mortalities of this species are called ‘walkouts’. When oxygen levels drop, lobsters move inshore where wave action causes mixing of the water and slight increases in levels of oxygenation. When low tide sets in, they are left behind on the beach or are washed up onto the beach by the waves,” he said.
Meanwhile, the Biodiversity Conservation Authority in KwaZulu-Natal, Ezemvelo KZN Wildlife, said it was investigating and checking samples to confirm what appeared to be a red tide.
“We are doing this in collaboration with research institutes. It extends from Westbrook to the mouth of the uThukela estuary. Once we have confirmation on the algal species, we will notify the relevant authorities who will be responsible for issuing the notices to the public if that is required, ” said Ezemvelo KZN Wildlife.
Cape Times