Climate change slows aquaculture
The maritime aquaculture sector – in particular the oyster industry – has stagnated in the past 15 years while the production of oysters has suffered mainly due to changed environmental conditions. These are just two conclusions of a conference recently held in Lüderitz.
03 March 2019 | Environment
A workshop titled Enhancing Climate Change Resilience in the Benguela Current Fisheries System was held in Lüderitz recently, where experts discussed the local aquaculture industry.
Amongst others, chief biologist for aquaculture of the Ministry of Marine Resources and Fisheries Frikkie Botes, highlighted the sector's problems based on statistics.
“There are many challenges, especially environmental ones,” he said, citing algae blooms, sulphur outbreaks, and changes in the temperature and pH of the ocean as examples.
According to him, his department awarded a total of 123 aquaculture licenses over the past 15 years. To date, only 14 companies are still in operation: six in Lüderitz, five in Walvis Bay, two in Swakopmund and one in Henties Bay. “You are the pioneers who survived,” he said in front of several industry representatives.
The stagnation of the sector was illustrated by Botes' reference to statistics. In 2003, a total of 230 tons of oysters were harvested. This figure rose to a record high of 700 tonnes by 2007.
“But, in 2008, only 390 tons were harvested. This was partly due to a combination of insufficient oxygen in the sea and sulphur outbreaks. About 80 % of companies have closed their doors,” he said.
A similar phenomenon occurred in 2010, and last year an oyster farm lost about 80 % of its harvest due to another strong sulphur outbreak and only 243 tons of oysters were harvested.
According to Botes, another factor that has an impact, are a regular and sometimes longer-lasting increased component of Diarrhetic Shellfish Poisoning (DSP) especially at the mussel farm near Walvis Bay where, since May 2018, regular tests have been carried out for DSP, meaning that the outbreak has been ongoing for around ten months.
The fact that the aquaculture industry faces great challenges was also made clear by Prof Peter Britz from Rhodes University, South Africa. “There will be big changes,” he said, referring to climate change.
According to him, the rise of sea levels as well as increased sea temperatures are often addressed in the media, but “there is not much published about the altered pH”, he said adding that a “change in the pH in the ocean will have a huge impact on shellfish and aquaculture”.
Nevertheless, “In the end, we know very little about how this industry is influenced,” Britz said.
For this reason, experts from the local oyster and abalone industry were consulted.
The workshop was a joint effort between the Benguela Current Commission (BCC), the governments of Angola, Namibia and South Africa as well as the United Nations Food and Agriculture Organisation, and the Global Environment Facility (GEF).