David Macgregor
PLANS to conduct a massive offshore search for potential undersea oil and gas reserves off the Eastern Cape have caused widespread alarm.
Fears have been raised about the possible impact the proposed two-dimensional Petroleum Geo-Services seismic survey would have on sensitive marine resources in the search area of more than 450000km² if approved by the government.
The five-month survey, which could begin in the next few months if a permit date is secured quickly enough, comes hot on the heels of controversial government approval to lift their moratorium on hydraulic fracturing – fracking – in the ecologically sensitive Karoo.
Border Deep Sea Angling Association (BDAA) environmental officer John Rance said they were concerned about the seismic survey's possible impact on breeding fish populations.
He said Western Cape fishermen were of the opinion similar seismic surveys on the west coast and around Cape Town had negatively impacted fish populations, leading to reduced catches.
According to the application for a reconnaissance permit to undertake a speculative 2D seismic survey Background Information Document (BID), issues needing investigation included noise effects on marine fauna; and effects on the fishing industry including fish behaviour, catches and displacement of fishing activities.
Attempts to obtain information on the process proved fruitless but Wikipedia describes seismic testing as an exploration technique for oil and gas sediments using large ships that fire high-intensity air guns deep into the ocean, reaching volumes of up to 260 decibels when used in an array.
It warns the sound energy from these air guns – which in the BID number between 12 and 70 and are fired at 10- to 20-second intervals – is potentially damaging to many species of marine life, including whales, dolphins and seals.
Scientists believe anything over 180 decibels can cause injuries to marine mammals.
Rhodes University marine expert Prof Peter Britz said available literature on the effects of speculative two-dimensional seismic surveys ranged from nothing to increased and-or reduced fish catches to damage to fish hearing membranes.
He urged the BDAA to register as an interested party and insist consultants do a thorough evaluation on the effects of the seismic guns on fish.
Cape Town deep sea angler Gary Thompson said many fishermen believed a similar survey off the West Coast from Cape Point earlier this year had had a huge impact on fishing resources.
