Monday, February 25, 2008

Downstream Peril

Waking up to the
Science Show on ABC Radio National was a shock. 40 percent of the world's oceans are heavily impacted by human intervention. Marine ecologist Ben Halpern from the University of California (Santa Barbara) was being interviewed by science journalist guru Robin Williams. Halpern made the point that 'nearly half of the ocean is suffering from a lot of multiple activities that are having a big impact on the oceans.'

But there is an optimistic note from his research. There are still pockets of healthy oceans - small patches that need to be preserved - in the poles and in Northern Australia. Halpern says that almost all sea-neighbouring nations have some healthy waterways remaining which offer 'real opportunities for effective management and conservation of these areas'.

Another commentator in the program outlined that the major contributors to ocean damage are climate change and commercial fishing, particularly bottom trawling which, like clear-fell logging, leaves nothing in its wake but giant plumes of dirt sometimes up to 20kms long. John Amos from Skytruth, an organization that tracks environmental damage using satellite imaging, says that the acres of sediments stirred up by trawling not only take everything, they also seriously impact the ocean floor, the rocky reefs and tiny organisms, they also affect the water's physical and chemical make-up. Amos paints a sorry picture of the legacy of bottom trawling or dragging.

'[A]s the sediment drifts with the ocean's current, eventually it settles back onto the sea floor somewhere, possibly burying the marine organisms that live there, maybe many miles from where the trawling itself actually occurred, perhaps even in some of those few areas of the ocean that we have placed off limits to trawling.'

These issues have been raised over the past decade by environment organizations and leading scientists such as Daniel Pauly who's Director of the Fisheries Centre at the University of British Columbia (UBC). Pauly found that people are affecting the ocean environment to such an extent that they are killing off the fisheries. He calls this process fishing down the food webs. This occurs when the larger fish such as the highly endangered Bluefin Tuna are fished out, so the commercial industry sources the next size down, then the next, and then the next, until what is left at the end of this process are possibly small fish species, algae and jelly fish.

Despite his research, Pauly sees a positive future for fisheries 'but only if they are reinvented not as the source of an endlessly growing supply of fish for an endlessly growing human population but as provider of a healthy complement to grain-based diets. Particularly, fisheries cannot remain a free for all for a pillaging distant water fleet; they can however, become a regular source of income for communities whose members act in accord with the finite nature of marine resources.'

If, as Halpern's research suggests, northern Australia, the Torres Strait and the Great Barrier Reef Marine Park area are still in healthy shape, let's try to keep it that way.