We may have survived 2020, but not everyone did.

It’s January and most of us are celebrating having survived the crazy year that was 2020. However, what role have we played in ensuring that the remaining natural resources on our planet could also see the light of the new year? Unfortunately, our unsustainable use of many natural resources is another pandemic that we have been turning a blind eye on. According to the IUCN Redlist of Threatened Species, in 2020 alone, 31 species (including one shark species) did not make it to the New Year and are now listed as extinct.

The aptly named lost shark (Carcharhinus obsolerus) that is likely extinct. Photo: Lindsay Marshall

A bit closer to home, South Africa has one of the most diverse and endemic shark populations in the world and subsequently, we have highly industrialised and artisanal shark fisheries. Some of these fisheries include demersal shark longlines, pelagic longlines, recreational line fishing, beach seines and gillnets. About half of the shark and ray species in our waters are caught in these fisheries, most notable are those like the soupfin, smoothhound, shortfin mako, and blue sharks.

Commonly caught sharks in South Africa's fisheries

Unfortunately, about a third of South Africa’s shark and ray species are considered at risk for extinction, a much higher percentage compared to the global average of 17%. Threats to sharks can include factors such as invasive marine organisms, climate change, and pollution. However, the major and most concerning threat to shark species is that of overfishing.

According to the National Plan of Action for the Conservation and management of Sharks (NPOA Sharks), the total South African shark catch is estimated to be 6,562t per annum (which is roughly the equivalent of 3,000 cars!). The scary part is that two-thirds of this reported catch is by-catch – meaning these sharks were caught by accident when fishers were targeting other animals.

Example of a longline, one of the shark fisheries that exist within South Africa. Photo: Marine Stewardship Councl

Sharks struggle under fishing pressure because they have a low capacity for reproduction and cannot easily replace individuals in the population that are fished out. For example many species have a slow growth rate and small litter sizes.

These shark declines are problematic because because it not only effects the sharks themselves, but they may also affect marine ecosystems more generally. Many shark species are at the top of the food chain, and if they are removed from these food chains, their usual prey will temporarily blossom and increase in numbers to a point where they overeat their prey, causing whole ecosystems to become unbalanced.

Sharks are known to keep ecosystems healthy. Credit: Warren Baverstock, Coral Reef Image Bank. IYOR 2018.

In addition to their important ecological roles, sharks are also valuable resources, for example in the Western Cape province, sharks are a major source of income in some of the fishing villages. Well managed shark fisheries based on the more productive species can sustain livelihoods but so, too, can shark based marine ecotourism.

The winning formula is to have sustainably managed shark fisheries, where both human and marine communities can benefit. This is obviously much easier said than done and requires a lot of knowledge into the species that are being fished.

Here in South Africa, while our government has taken certain steps towards the management and conservation of sharks (for example shark finning is banned), there is still much to do. Even though we catch nearly 100 species through the various fisheries, stock assessments (which tell us if the species are being fished at sustainable levels) have only been attempted on 5 species. More effort dedicated to research and appropriate management strategies are required to ensure that our sharks are being fished at sustainable levels, a solution that benefits everyone involved.

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References:

da Silva, C., Booth, A., Dudley, S., Kerwath, S., Lamberth, S., Leslie, R., McCord, M., Sauer, W. and Zweig, T., 2015. The current status and management of South Africa's chondrichthyan fisheries. African Journal of Marine Science, 37(2), pp.233-248.

Department of Agriculture, Fisheries and Forestry., 2013. National Plan of Action for the Conservation and Management of Sharks (NPOA Sharks). South Africa.

https://www.iucn.org/news/species/202012/european-bison-recovering-31-species-declared-extinct-iucn-red-list