Giant roman at Photographer's Reef

Lecture: Colin Attwood on the effectiveness of South Africa’s Marine Protected Areas

Colin Attwood is a professor in the zoology department at the University of Cape Town with a special interest in Marine Protected Areas. Tony and I attended a talk by him at the Save Our Seas Foundation Shark Centre on the same evening as the talk about Baited Remote Underwater Video Stations (BRUVS) in False Bay. The two talks dovetailed nicely, since the aim of the BRUVS project is to enable more effective monitoring of our Marine Protected Areas.

The South African coastal waters are under threat from a number of directions. Resource extraction (mining, oil drilling and the like) carries a danger of catastrophic pollution and spills, and the craft used for these activities are often vectors for alien species. Aquaculture, which may seem like a good idea, also threatens to introduce alien species to sensitive areas of the coast, and generates huge amounts of pollution too. Municipal failures such as sewerage spills, plastic pollution, and most of all fishing are the other big threats to the integrity of the ocean habitat. A future threat to our coastline is phosphate mining (the phosphate would be shipped to China and Australia to rehabilitate farmland), and demersal trawl fishing is a constant threat to large areas of the coastline.

The scale of fishing in South Africa’s coastal waters is terrifying: 800,000 tonnes of marine life is harvested annually. About 300 species (including invertebrates such as abalone and rock lobster) are targeted, but about 550 are impacted, many as bycatch. To put that in perspective, there are about 2,200 fish species found around our coastline.

South Africa has a fairly extensive network of MPAs, covering 19% of our coastline. 9% of the coast falls within no-take zones, where nothing is to be removed by fishing or other methods. If one rather measures the extent of our MPAs as a percentage of our exclusive economic zone (EEZ) which extends 200 nautical miles off our coastline, they cover only 0.4% of South Africa’s territorial waters, and only 0.16% of our EEZ is a no-take zone. The west coast of the country is largely neglected, but other than that the MPAs are distributed quite evenly around the coastline.

Marine protected areas protect habitats and ecosystems, as well as commercially important fish populations. They do this by preventing fishing in nursery areas and locations where spawning takes place, as well as by preserving the genetic structure of the population. They allow research into the effects of fishing to take place by providing areas that aren’t fished to compare with areas that are. They also enable non-consumptive activities such as scuba diving, whale, seal and seabird viewing, and coastal tourism to take place.

One interesting aspect of MPAs that Prof Attwood pointed out is that they are used for crowd control. Anyone who has seen the number of vehicles on the beach at Sodwana during high season might think that this is terribly destructive and not what an MPA should look like. What is in fact taking place is that 95% of the people are being funnelled through 5% of the MPA, constraining the damage done by human activities to a very restricted area.

Redundancy in Marine Protected Areas, as in engineering, is a good thing. If a species exists in more than one MPA, it is less vulnerable to habitat destruction and catastrophic events such as oil spills. One of Prof Attwood’s students has done work on whether all our marine species are adequately protected (i.e. appear in at least one, and preferably more than one MPA). The results are sobering – of the 225 shore species surveyed, 26% of them do not live in any of our MPAs and 85 species only exist in one MPA. Of the inshore species surveyed (230), 33% are not in an MPA. 25% of the 145 estuarine species surveyed do not live in any of our MPAs, and of the 446 species found out in up to 500 metres on the deep continental shelf, 78% of them are not in an MPA. Only two MPAs (Pondoland is one) cover any of these species at all!

Prof Attwood then gave us a rapid tour through the important scientific studies that have been conducted in South African MPAS. It was only in the last 20 years that the scientific community shook off its skepticism that Marine Protected Areas – underwater, without fences – would actually work. The results are very heartening, and numerous studies have confirmed MPAs efficacy. Fish are more abundant, and populations of heavily exploited fish recover remarkably rapidly and thoroughly when fishing pressure is removed. I first read about this in Charles Clover’s book End of the Line, where he describes an MPA in New Zealand, at Goat Island, and what a delight and amazement it is to the locals and tourists who get to encounter abundant fish in knee deep water.

Giant roman at Photographer's Reef
Giant roman at Photographer’s Reef

Roman inside the Goukamma MPA (8 x 1 nautical miles in dimension, along the coast near Knysna) are on average larger, and change sex later. Roman change from female to male at a certain age, but fishing pressure outside the MPA has forced a physiological change in the fish: their sex-change takes place at age 8 instead of the usual 10 years. The roman inside the MPA are thinner and in poorer condition than those outside the reserve, where fewer fish means less competition for prey. This is at first blush a strange result, but makes complete sense given the higher density of fish inside the MPA – and perhaps these “thinner” roman are fit, compared to the chubby, overfed ones outside the MPA! Prof Attwood pointed out that MPAs are not good for all species – the example here is the crinoids (feather stars) that romans love to eat. Inside the MPA there is a significantly lower density of feather stars than outside, where fewer roman prey on them.

The talk concluded with a map showing analysis of where South Africa’s next MPA should be located. It’s possible to identify critical locations where species that are not widespread live or breed, and these are the areas that should be protected. Tony and I both found this talk extremely inspiring and encouraging, as Prof Attwood does not do the kind of science that gets shelved somewhere and forgotten about. The results of his work are useful in policy making, legislation and decisions about the protection and use of our common marine resource, and he is active and willing to participate in that aspect of marine conservation.

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Clare

Lapsed mathematician, creator of order, formulator of hypotheses. Lover of the ocean, being outdoors, the bush, reading, photography, travelling (especially in Africa) and road trips.

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