Page 269 - Manual for Activities directed at the Underwater Cultural Heritage

relatively well for heritage located at the bottom- surface, while deeply buried cultural heritage is difficult to detect and can only be predicted. Nevertheless, these development projects at sea and the associated impact studies have resulted in major development-led research projects and it is a great challenge for archaeologists to make the most of this development-led research, also in relation to the construction of offshore islands and the dredging for aggregates that make landfills and reclamation possible.
Fisheries are yet another matter. In contrast to offshore development projects, their impact is not negotiated on a project-to-project basis but general policies have and can be developed. In the past, the impact of fishing on the sea-bottom was not recognized as a problem. Ships engaging in seabed- impacting fishing used to be wind-propelled or had limited engine power, while larger industrial factory ships all use so-called benthic techniques, catching fish in the water column, rather than at the sea- bottom. With the increase in engine power, shallow water trawlers with ground-tackle have upgraded their equipment to 4000 hp and even double this in more specialized instances. The severe impact of this development has made it a major concern for environmentalists. As a consequence, many countries have devised policies to ban these fisheries, or limit them to less powerful ships. The fishing techniques themselves have also changed. Ground tackle that literally ‘ploughs’ through the bottom-surface with great energy and force is being gradually out-phased in favour of tackle of a more hovering kind. The
© CEMEX UK Marine Ltd, Hanson Aggregates Marine Ltd
& United Marine Dredging Ltd. Scars made by bottom trawling shown by a high resolution side scan sonar record of the sea bed immediately to the west of the Hastings Shingle Bank licence area, United Kingdom.
Sandy bottoms where bottom trawling is permitted show the impact and scars of this activity that impacts all cultural heritage on the bottom surface.The scars frequently extend beyond the fishing zones.The scars in the right corner derive from dredging.
This image was taken in the framework of the detailed Environmental Impact Assessment for a marine aggregates extraction project in the UK. Marine aggregates play an important
part in the provision of high- quality raw materials for both
the construction industry and
for coastal protection. In the
UK permissions for aggregate dredging are given for 15
years only after a detailed Environmental Impact Assessment and stakeholder consultation process with 5 yearly reviews. Although this activity is strictly controlled, and relates to only
a very small area of seabed, concerns have been raised that removal of dredged material may impact on environmental resources of conservation and economic significance.
268 main driving force is certainly to economise on fuel,
Environment