People have been harvesting heavily from the sea for centuries; slowly and in some cases rapidly depleting our marine resources. These marine resources are of extreme importance to all of us as a food source but also as a means of recreation. Unfortunately a rapidly increasing human population, needing more food and more recreation, is placing unsustainable stress on our marine resources. In South Africa we have been witness to some severe cases of this stress where a total collapse of certain species has occurred (e.g. seventy-four, red steenbras etc.). Although it is obvious that we should be allowed to have reasonable access to harvest these resources, are we not killing the goose that lays the golden egg?
Consequently, it seems that everywhere we look these days, we are bombarded by conservation messages about sustainable utilization of the sea and a seemingly endless list of restrictions is placed on how we interact with the sea. Okay, so what do we need to understand? In South Africa harvesting of linefish from the marine environment is mostly done for recreational or commercial purposes. Commercial harvesting is regulated by limiting the number of vessels and crew that harvest from the sea (i.e. total allowable effort), while the catch itself has limited restrictions. This is done to make the fishery profitable for the participants and provide fresh fish to the non- fishing public, while still restricting the total harvest to sustainable levels.
Conversely, anybody who wishes to fish for recreation can do so provided they purchase a fishing license. This is known as an open access fishery and because an infinite number of people can potentially enter the fishery, limiting the amount of fish caught is the only way to conserve stocks. This is done by traditional fisheries management measures such as bag limits, size limits and closed seasons.
Unfortunately, traditional fisheries management measures are not coping and many fish species are continuing to decline in number. The biological data on which bag limits, size limits and closed seasons are based needs periodic revision because of fluctuating fish populations. Research has shown that many of the linefish regulations introduced in the mid-1980s were too generous and have not been effective in ensuring sustainable use. For example, many of the daily bag limits set for linefish species have had to be greatly reduced to make them more effective. Furthermore, minimum size limits are traditionally set at the size at which a fish species reaches 50% sexual maturity. This protects the fish when they are small and growing quickly and it also allows them an opportunity to spawn before being caught.
However, larger fish of a certain species produce exponentially more eggs than smaller fish and the eggs that they produce are more viable and genetically fitter, since the parent has obviously been successful at surviving the trials of life. However, we have no real examples of maximum size limits in our legislation with dusky kob being the only exception.
So if we have declining fish stocks and traditional conservation measures are not coping, what can be done? Marine protected areas or MPAs are areas of the sea and the adjacent coastline which have been reserved by legislation so that human use is regulated – similar in some respects to a terrestrial game reserve. MPAs are often zoned for different types of human use with each zone having its own specific restrictions.
In South Africa, our MPAs are usually zoned into “A” (no-take sanctuary), “B” (restricted use e.g. game-fishing for migratory species) and/or “C” (controlled use) zones. The iSimangaliso Wetland Park, Aliwal Shoal and Pondoland MPAs all have no-take sanctuaries where no extractive utilisation is allowed. Sometimes sanctuaries can even be zoned as absolute no-go areas where mere human presence is prohibited.
No-take sanctuaries may be formed for different reasons but generally serve as either an ecosystem reserve where fragile habitats and species are protected or as a fishery reserve to improve adjacent fished areas. A MPA therefore has local and regional effects – the so-called “reserve-effects”. The local effect is what happens inside the sanctuary. Potentially threatened species are provided with a refuge and are allowed to naturally increase in size and abundance. Many of our reef fish species change sex and some species require a ratio of one large dominant male to several females or vice versa for successful spawning to take place.
In exploited areas it is normally the larger, more dominant individuals that are captured first, thereby skewing the natural sex ratio making it more difficult for spawning to take place. In a no- take sanctuary natural sex ratios are preserved enabling fish to spawn successfully. Successful spawning also depends on the densities of fish; there should be enough fish in a given area for males and females to find each other. In the well sited sanctuary areas that are large enough, fish are able to reach maximum sizes and numbers allowing large numbers of eggs to be produced. These and other effects have been proven in many studies around the world.
But, it is the regional effects that are important
to us as recreational harvesters – what the no- take sanctuaries provide to us in the adjacent exploited areas of the ocean. This is a lot more difficult to prove.
Nevertheless, it is logical to expect emigration of fish from the sanctuary once the number of fish increases and reaches carrying capacity – a term known as spill-over. It is also logical to expect that pelagic eggs and fish larvae spawned in the sanctuary will drift with ocean currents into adjacent areas – continually seeding fished areas with new stock.
A well sited network of MPAs and sanctuaries can therefore supplement the traditional fisheries management measures in conservation and sustainable use of our marine resources.
Although MPAs have been around for some time now, the extent of their influence on marine fish communities is not that well understood. This has caused widespread controversy over the effectiveness of MPAs especially with the loss of fishing grounds that fishermen experience when an MPA is proclaimed. South Africa is reported to protect nearly 20% of the coastline in MPAs (as recommended by the World Parks Congress -2003), yet only 9% is fully protected by no- take sanctuaries. If one considers the total area protected within MPAs in South Africa’s Exclusive Economic Zone (EEZ which stretches out 200 nautical miles from the coast), then less than 1% falls into a fully protected MPA.
Critics of MPAs say that by eliminating harvesting in one place, effort is concentrated elsewhere putting extra strain on those areas. Although this point of view may have some merit, this equates to little more than an increase in harvesting effort. Ultimately increasing human population and open access fishery is already achieving this. Without no-take sanctuaries we will never have the much-needed “reserve-effects”.
Furthermore, we will not have the necessary benchmark that MPAs provide which allow us to measure just how much we are impacting on the ocean’s resources. One of the more recent MPAs to be proclaimed in South Africa is the Pondoland MPA in the Eastern Cape, running from the Mzamba River to Port St Johns. This MPA includes a ~40 km2 no-take sanctuary for any vessel- based fishing which runs from the Sikombe River in the north to Mbotyi River in the south. The MPA is currently being monitored by scientists from the Oceanographic Research Institute.
Four similar sample sites have been identified, two inside the no- take sanctuary area and two in the adjacent fished area. On a quarterly basis each area is fished for the same amount of time by the same anglers using standardized bait and tackle. As an indicator of fish abundance, ORI scientists use the average number of fish caught per angler per hour (catch per unit effort or cpue). As can be seen in Figure 1, the sanctuary always outperforms the adjacent open area and sometimes the CPUE in the sanctuary is as much as double that in the open area.
See Figure 1 below. Unfortunately, the problems with declining fish stocks are not unique to South Africa; a global crisis in fisheries has been recognised for some time. Never before has so much pressure been exerted on our marine living resources on such a grand scale; and we are now realising that on their own our traditional fisheries management measures, the bag limits, size limits and closed seasons are not coping. Not only do MPAs provide a supplementary method of fisheries management but also they provide the “reserve-effects” – many untold benefits that no other management measure can provide. As spearos we can be highly selective of our catch, but if we hope to experience the same abundance of fish to choose from in the future, it is important to support MPAs. As custodians of our marine resources, we have the obligation to support MPAs, without which, they will ultimately fail.