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Photo: Oddgeir Alvheim
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Garbage pollutes deepwater habitats

The research vessel “Dr. Fridtjof Nansen” is currently conducting a deep water trawl survey focusing on the slope and deep water biodiversity off Ghana in central West Africa. The survey has documented several fish species never before recorded in Ghanaian waters and, amid it all, human waste as far down as 1000 m depth.

Av Jens-Otto Krakstad, Oddgeir Alvheim and Tomio Iwamoto 

You might think of the vast marine ocean floor as a pristine environment, at least when moving away from the coast and into deeper waters, far out of reach of any man. The current deepwater trawl survey off Ghana may well be the first to trawl here at these depths. However, what we find is frightening evidence of mans impact on mother earth.

Physiculus cyanostrophus

Photo: Oddgeir Alvheim

Catching waste

In bottom trawl hauls at nearly 1000 m depth and 50 km from the coast, what came up are paint buckets, soda cans, plastic debris and a shoe insole. Unfortunately, these are not just “lucky hits”.
Quite regularly, amid species rarely seen by mankind, the trawl brought up evidence of human activities, mainly plastics that do not easily break down, “ghost” fishing nets, polyethylene ropes etc, as well as metal containers and other more degradable debris.

Rhinochimaera cf africana

Photo: Oddgeir Alvheim

Heavy traffic

So, where does it all come from?
We know that human waste concentrated in oceans by current systems. Upstream from us is an oil platform. However, it is as far away as the shore. We are also in an area with heavy ship traffic, international merchant ship travelling to and from Tema and other regional shipping hubs, supply vessels for the oil industry and small local fishing vessels. And lastly, rivers in the area bring to sea household garbage that are taken by the current and transported over large distances.
Not all vessels follow the regulations intended to limit disposal of waste imposed on them by various international bodies. Dumping of garbage at sea still poses a serious international pollution problem. Unlike on land there is no easy means of retrieval, sorting and recycling of plastic waste that enters into the ocean environment. Today we still do not know how quickly plastics disintegrate and eventually break down at sea, but we know it takes a long time. For some types of material it may take in excess of 500 years to disintegrate and their poisonous by-products will still be there. Clearly our actions today will affect the marine environment for future generations to come.


Read more about The Centre for Development Cooperation in Fisheries (CDCF)