Offshore Dredging ‘Contaminates’ Oysters

The Namibian fishing industry has accused Namibia Ports Authority (Namport) activities for the increase in cadmium levels detected at some oyster farms located between Walvis Bay and Swakopmund.

Cadmium is a metal that exists naturally in the earth’s crust. It is also a pollutant released by industrial activities like the production of pigments, plastic stabilisers and nickel-cadmium batteries, electroplating and mining.

For non-smokers, food is the main source of exposure. Although acute intoxication may damage the gastrointestinal tract and affect liver function, such dietary exposure is very unlikely.

Speaking at a press conference at Walvis Bay last week, the chairperson of the Confederation of Namibian Fishing, Matti Amukwa, said Namibian oyster farms are monitoring their oyster food safety levels, and a farm outside the bay towards Swakopmund has detected abnormally high cadmium levels.

He said the fishing industry has never experienced or detected high levels of cadmium in the past and that this could have a negative impact on Namibian fishing products, especially oysters and other shell fish that are exported internationally.

Amukwa believes that this could be caused by dredging that is ongoing at Namport for the expansion of the port.

“Dredging is whereby the bottom sediment is sucked up potentially including trace heavy metals, and currently around 2 000 tonnes of dredge material is dumped at sea daily off Pelican Point. There are indications that sediment from that dredge waste remains floating in the water column for a period of time, and is swept north by the g northerly current and eaten by the oysters. We have never detected this in the past,” he elaborated. Amukwa said this has already raised alarm bells, making the entire industry jittery regarding the implications marine phosphate mining dredging could have from a seafood safety perspective.

“The fact that Namibian aquaculture grown oysters are picking up higher levels of cadmium downstream from dredging activities in Walvis Bay has potentially serious implications for the Namibian fishing industry and we cannot have the future of the Namibian seafood industry put at risk. Proper, independently research must occur before any decision is given to go ahead with marine phosphate mining,” stated Amukwa.

Meanwhile, the port engineer at Namport, Elzevir Gelderbloem, has confirmed that the issue has been brought to their attention. “However, we are still waiting for the aquaculture guys to prove that Namport is the cause of their problems. It is obviously very easy to blame Namport while there is no proof,” he stated.

Gelderbloem added that Namport has obtained expert aice which in fact shows that the aquaculture farm at Patrysberg close to Swakopmund is in an area where naturally occurring cadmium in the water is high due to natural upwelling currents in that area.

“We have not done any significant dredge dumping at sea over the last few years since we use most of our dredged sand for land reclamation currently, thus their accusations are unfounded,” he said.

“We recommended that they conduct a scientific study to identify the cause first before pointing fingers at us,” further stated the engineer.

Source : New Era