After halting the seismic survey in Algoa Bay on Thursday peace an quiet descended upon our marine neighbours for a day, only for permission to be given for the seimic survey to begin again lat on Friday afternoon.
The call of the blue whale reaches levels up to 188 decibels. This extraordinarily loud whistle can be heard for hundreds of miles underwater. Theoretical calculations by Roger Payne and Douglas Webb (from the 1970?s) predicted that the loudest whale sounds might be transmitted across an entire ocean. The blue whale is much louder than a jet engine at 30 metres and reaches 130 decibels, a screaming child measures up to 110 decibels, the space shuttle lift off reaches 180 decibels and the Nelson Mandela Stadium reaches 100 decibels and more.
According to the Alaska Marine Conservation Council, a typical seismic survey lasts 2 to 3 weeks and covers a range of of up to 1000 kilometres. Sound waves fired from seismic air guns are up to 250 decibels loud (enough to make your ears bleed) near the source and can be as high as 117 decibels up to 30 kilometres away.
Imagine if you will a sound source larger than the Nelson Mandela Bay Stadium hovering over your home for 6 weeks blasting out sound at 2.5 times it’s normal loudness! You woulodn’t be happy and I am sure that our marine animal neighbours are pretty miffed at the moment as well. Seismic surveys have been found to kill adult fish, larvae and eggs at close range.
The Polarcus Nadia is currently conducting a seismic survy in Algoa Bay. This vessel is presently towing a configuration of ten streamer cables each of 6 km length spaced 100 meters apart at an average depth of 10 m astern of the vessel. The streamers are not visible on the surface. The vessel completes a tight computer controlled pattern in a block as you can see in the image below:
On Thursday 19 December 2013 South Africa’s Petroleum Agency of South Africa (Pasa) halted the seismic surveys pending discussions between international oil firms and local environmentalist, Paul Martin, who blew the whistle on the out-of-season tests.
“The agency has deemed it imperative to suspend seismic operations until the process of consultation is completed, and a report submitted to the agency this week,” spokeswoman Althea Adonis said.
After studying the report, Pasa will “apply its mind and decide whether to allow seismic operations to recommence or not,” she added.
Local environmental consultant Paul Martin complained to Pasa this week over non-compliance with an environmental management programme.
The plan allows for the survey from January to mid-March every year, but explorers had already started in December, which disrupted the seasonal migration of humpback whales, said Martin.
“This is the first stage of oil exploration off the coast and they go and stuff up the first stage. They just ride roughshod over what was agreed,” he said.
“We all want sustainable development, but if at stage one those involved aren’t going to comply with what is in their authorisation, what trust do we have in them?”
Five international companies, among them Anglo-Dutch Shell and London-based NewAge African Global Energy, have licences for seismic surveys along the east coast from Jeffreys Bay to the Wild Coast.
The suspension was short lived though as, on Friday afternoon Pasa lifted the halt on New African Global Energy (New Age) South Africa’s seismic survey, sayng that the oil company had agreed to modify its exploration methods so as not to affect the whales’ movements along the coast.
New Age said it had created a “no-activity buffer zone” stretching 10km from the Addo Marine Protected Area and would take responsibility to “minimise any potential impact on the marine offshore environment” while conducting its three-dimensional seismic survey. The company also had two marine mammal observers and a “passive acoustic monitoring observer” on board its survey vessel who continually monitor for the presence of marine mammals.
“If any whales or other marine mammals are present inside 500m from our vessel before recording on each survey line … we wait until they are clear before commencing operations. We will always take action, as required by our environmental management plan, to avoid any harm to wildlife in this area,” the company said in a statement.
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