A scientific study conducted by researchers from the Algarve University and Oceana, the world’s largest organisation dedicated exclusively to ocean conservation, discovered a “large quantity of litter in the upper São Vicente (St. Vincent) submarine canyon off southwest Portugal.”
In just three dives into the canyon the team’s underwater robot documented 115 pieces of rubbish - the majority of it discarded fishing equipment – some at a depth of 500 metres.
The St. Vincent canyon is located 12 kilometres off the Portuguese coast, off Sagres, in the Algarve, and measures 120 kilometres in length.
A note from the report stressed that “this type of waste degrades slowly in deep areas and it is likely that the quantity of such waste will tend to increase.”
The study, published in the Marine Pollution Bulletin, is based on three sub-aquatic dives by the ROV robot, carried out in 2011 at depths of between 93 and 533 metres, and saw scientists analyse more than nine hours of footage.
Frederico Oliveira, a researcher from the Algarve University’s Centre for Sea Sciences who participated on the project, explained: “In this region, fishing is a very important activity from the socio-economic point of view. What we observed in the canyon of St. Vincent is similar to that described in other parts of the world where fishing is the main activity.”
However, he said “Unfortunately, the methods of control and minimisation of fishing gear loss are currently ineffective. The long-term effects (...) are still poorly understood, particularly in the deeper parts of the ocean. These deep habitats, many of them still little studied, are home to sensitive species of slow growth that can be quite vulnerable to disturbances.”
Ricardo Aguiar, head of investigation for Oceana Europe, added: “Practically nine out of 10 residues found in the St. Vincent cannon are abandoned cables and networks. This is very disturbing since they are made with resistant synthetic materials whose degradation processes are very slow in deep zones.”
Nearly one third of the litter found was in some way directly affecting the flora or covered the seabed, while over eighty percent of the findings occurred in rocky areas.
So, Aguiar warned: “Either measures are adopted to prevent the loss of fishing materials, or the amount of waste will increase continuously in the coming years.”