| Shark nets in South Africa: O, what a tangled net we weave |
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By Pamela Le Noury for Shark Savers
Pamela is a marine scientist who is frequently involved in shark tagging efforts in South Africa.
Humpback whale
The Humpback whales that we see every year off Durban usually live in the freezing waters of the southern ocean around the Antarctic. The cooler waters hold more oxygen and therefore sustain more plankton, in turn more fish and generally more life. Humpback whales eat small morsels such as krill which flourish in the cooler waters, as do the whales. But being warm blooded mammals in near zero temperatures is not always easy, especially for new born calves, and it is for this reason that the whales make an enormous and epic journey half way across the globe towards the equator to breed, where the calves have a much better chance of survival in the warmer waters. At the end of summer, many female whales will have been pregnant for almost a year. They start to leave the secluded Antarctic waters at this time and head north. The journey is long and tiresome, usually crossing the enormous currents that swirl around the uninterrupted oceans down south. The whales that come towards the east coast of Africa each year will further be confronted with the Agulhas current, one of the most powerful forces on earth. They must swim directly against this current and keep heading north until they eventually reach subtropical and tropical waters off Mozambique where the water is sufficiently warm to calve. Many follow the contour of the land masses up the east coast, the gauntlet includes large ports like Durban with many ships. They will pass the old whaling stations on the bluff where thousands of their kind met their fate. Many of the larger whales around today will have been around during the whaling days. The impressiveness of this journey is compounded by the fact that the whales barely eat the entire time! The opportunities to feed up here are almost non existent and the whales may spend months without food. It is an enormous sacrifice to make. In addition, males making the journey are trying to mate which means: courtship. The courting rituals of Humpback whales include, among other things, singing and breaching. Can you imagine the energy used to launch a 40 tone animal clear out of the water? It is quite astounding. Whale trapped in net
Shark net.
The navy started depth-charging, physical cage-like barriers were installed but later abandoned as they were unsuitable in the high impact surf. By 1962 modern shark nets were installed at more beaches and by 1966 fifteen beaches had net installations in place. Since the installation of the shark nets, combined with increased fishing effort, shark numbers have been systematically reduced, and the chances of shark attack have dropped to near zero. The nets were very effective in reducing shark numbers, thereby providing a solution to the economic and humanitarian crisis that ensued after 'Black December’. Shark trapped in net
The other event was the end of whaling. This is much more related to the fate of sharks than people realise, because it was the whaling station which attracted and sustained such an abnormally large population of abnormally large sharks. The whaling station killing thousands of whales and sending a bloody, oily slick of whale juice up and down the coast from the Bluff. Moving with the wind and current, this smorgasbord of shark bait would arrive at Durban’s beaches to the north or Amanzimtoti to the south, the exact sites of the most shark attacks during the peak of the whaling industry. Furthermore, several whales were lost entirely to the sharks as they would bite through the blubber and sink the entire whale en route to the shore. This high-energy endless supply of whale meat created super-sized sharks, in enormous numbers that probably inspired dear Mr Benchley’s imagination. The end of whaling in 1975 should have gradually allowed for the end of the super-shark, shark numbers would have normalised, and the nets could have been reduced accordingly. But with everyone incited against sharks by this time, there was not a hope on earth shark conservation would begin. Shark trapped in net.
What this means is that if you remove all the shark nets today, you are not at risk of shark attack today, you are at risk in a decade or 2 when shark numbers have recovered. But with all the other, larger threats to sharks today, they are more likely to be extinct in a decade or 2 than for their numbers to recover. You are no more protected at a netted beach than at an adjacent non netted beach since the ‘fishing effect’ of the nets will have reduced shark numbers on both beaches (the ‘dangerous’ sharks roam over large areas, and aren’t confined to a particular beach). In fact it can be argued that you are safer at a non netted beach adjacent to a netted beach over the weekend when the nets are not serviced, therefore any animal caught in the nets on a Friday or Saturday or Sunday will spend the rest of the weekend essentially chumming the water. But again, the risk is so low, shark numbers are so depleted, that this ‘risk’ is purely hypothetical. Turtle trapped in net
The shark nets are systematically being complemented with drum lines. An anchored hook is baited off the bathing area and any sharks in the bathing area should be attracted to this trap. This is theoretically an improvement on the nets in terms of by-catch. Whale, dolphin, ray and turtle captures will be reduced significantly. It’s hard to say what it will do for the sharks: there are arguments that it will have a negative impact on certain vulnerable species, and arguments that it will be better off for sharks in general. Time will tell, but sharks don’t have that much time. Shark trapped in net
Another whale calf has died in the nets. It’s a tragedy for the mother, but the steadily growing Humpback population can probably sustain this loss. The tragedy is that the nets are still in place, when all the reasons to install the nets have disappeared. The tragedy is that everyone cares much more for a whale calf which enjoys protection by a global ban on whaling, than for the hundreds of sharks dying every year in the nets or the estimated 100 million sharks that die every year worldwide, and who have no protection. The tragedy is that our whaling operations caused a boom in shark numbers, and an insignificant amount of high-publicity human deaths resulted in the mass global extermination of sharks for decades to come. Shark trapped in net
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