Cold Benguela Current provides abundant fish resources - News - Gondwana Collection

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Cold Benguela Current provides abundant fish resources

Avatar of inke inke - 13. septembre 2019 - Environment

Heaviside Dolphins near Lüderitz. Photo by Lüderitz Marine Research

Brigitte Weidlich

The Namibian coast is known for its abundance of fish and this is due to a cold ocean current running from south to north near the mainland. The Benguela Current and its marine ecosystem has fascinated many scientists and might soon be declared a UNESCO World Heritage Site.

The abundance of fish attracts natural hunters such as seals, sea birds and predatory fish. Even whales are being spotted again on Namibian coastal areas, after they were almost wiped out by whaling. On the small coastal islands, even penguins can be found.

Namibia's fisheries sector, with around 16,800 direct jobs, also benefits from the Benguela Current. In the financial year 2018-2019, the Ministry of Fisheries has allocated catch quotas totaling 505,646 tons of fish. The fisheries sector contributes about N$10 billion (about 622 million Euros) to Namibia's economy. Sea transport through the two ports of Walvis Bay and Lüderitzbucht, as well as the mining of diamonds and in the future oil, gas and other minerals are important industries.

The small port of Lüderitz in southern Namibia is also a tourist attraction. Photo by: NamPort

Cold current from the South Pole

The cold Benguela Current is fed by Antarctic waters in the Southern Atlantic Ocean, which flow from the southernmost point of Africa, the Cape of Good Hope, northward to the equator. The cooling of the air temperature by the Benguela Current prevents moist air to rise from the ocean surface, which in turn causes wind currents, known as a steady southwest wind.

Beneath the surface of the Atlantic, mountains close to the coast cause the Benguela River to flow very close to the Namibian coast. The speed of the current has been measured at between 16 and 40 kilometres per day.

The Benguela Current is therefore a major cause of the existence of the Namib Desert and the harsh coastal climate with very low rainfall. At the same time, the Benguela is very rich in oxygen, zooplankton and other nutrients, which attract schools of fish. Due of the abundance of plankton and additional nutrients, large shoals of fish follow the current and make South Africa and Namibia among the coveted fishing grounds of this earth.

When reaching the equator, the Benguela Current flows into the Atlantic South Equatorial Current, which in turn feeds the Gulf Stream and the Brazil Current with its warm waters.

Illustration of Benguela Current. (Wikimedia)

Protection and sustainable use

Until Namibia's independence in 1990, South African and other international fishing vessels overfished and virtually depleted Namibia’s fish resources. The new government has therefore taken swift action and regulated fishing by law. Compliance with the allocated fishing quotas is strictly controlled.

In 2007, the Benguela Current Commission (BCC) was established with Namibia’s neighbours, Angola and South Africa, to ensure the conservation and sustainable use of biodiversity in the marine eco-region of the Benguela Current. The BCC Secretariat is located in Namibia.

In March 2013, the three member states signed the Benguela Current Convention (BCC). It is a groundbreaking contract for the protection and sustainable use of the cold stream. With the support of Germany’s Federal Ministry for Environment, Nature Conservation, Construction and Nuclear Safety, a protection project is currently implemented through the GIZ (Society for International Cooperation) since 2014. It will end in 2020.

In 2015, the governments of Angola, Namibia and South Africa ratified the Benguela Current Convention. Thus, the three countries recognise their cross-border natural capital and promote the management of the common marine ecosystem. The aim is to realise a holistic vision: the socio-economic development potential of the maritime area should be exploited in such a way that all industries and the societies of the countries can profit sustainably from it.

The project supports the Benguela Current’s sustainable marine use by implementing maritime spatial planning.

The new container terminal at Walvis Bay started operations in August 2019. Photo by: NamPort

"The goal is to have the right activity in the right place to sustainably promote the development of the region's maritime economy, so that people and the environment benefit from it," the GIZ describes the project. Particularly protected natural areas, the so-called "ecologically or biologically significant marine areas" are being identified. For each of the three member countries, a marine spatial plan is developed.

Benguela Current soon a UNESCO World Heritage site

The three countries are in the process of evaluating the current state of human use in their planning areas. Since the end of October 2016, the marine ecosystem of the Benguela Current has been on Namibia's tentative list for nomination as a world heritage site. The tentative list is a suggestion of future nominations for inclusion in the UNESCO list of cultural and natural heritage sites of the world.

The application was filed in March 2016. As justification, the Namibian authorities have stated that between 34° S and 15° S from the South African coast to the geopolitical border between Namibia and Angola, the Benguela ecosystem sites constitute a large marine ecosystem. "The ecosystem is characterised by high productivity and is defined by the Benguela upwelling," the motion reads. "The Benguela Current is powered by the predominantly southeastern trade winds of the South Atlantic”.

Along the coast of the actual Benguela Current, coastal updrafts are formed, forming the Benguela updraft system, the most important being situated off the coast of Lüderitz. This updraft area is linked to a Namibian marine reserve along the southern Namibian coast and adjacent islands. The rise of cold, nutrient-rich water from a depth of about 200m to 300m results in high-growth rates of phytoplankton that support the Benguela ecosystem. The intensity of the operations is determined by the wind force.

Biodiversity is an important factor

Mainly the coastal islands like Mercury Island, Ichaboe, Halifax and Possession Island host the entire Namibian breeding population of Cape gannets (Morus capensis), 96 percent of the Namibian population of the endangered African penguin (Spheniscus demersus) and nearly a quarter of the world population of crowned cormorants (Phalacrocorax coronatus).

African penguins at Halifax Island near Lüderitz. Photo by: Lüderitz municipality

pproximately 80 percent of the world's population of the endangered Cormorant species (Phalacrocorax neglectus) breeds on the Mercury and Ichaboe islands. From there they search for food on the ocean, covering many kilometres before returning. An estimated 16,000 penguins, 1,200 Cape gannets and 5,000 cormorants live alone on Mercury Island, which covers three hectares.

The endemic Heavisides dolphin (Cephalorhynchus heavisidii) and a considerable number of whales are regularly found at sea in Namibian waters. Large colonies of Cape fur seals (Arctocephalus pusillus pusillus) occur near updraft centres along the coast, including Lüderitz, Cape Cross and Cape Frio. Nearly 70 percent of the world's population of this seal species lives in colonies there.

It is not yet known when UNESCO will announce its decision to consider Namibia's proposal and declare the Benguela Current’s maritime ecosystem a world heritage site. 

Seals usually catch fish in deeper waters but this one near Lüderitz caught this bluntnose guitarfish at the beach. Photo by: Lüderitz Marine Research
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