i'lhtil A/JPG AjATJrJCJAL FiB DISCLAIMER Portions of this document may be illegible electronic image products. Images are produced from the best available original document. Creating artificial reefs from decommissioned platforms in the North Sea: review of knowledge and proposed programme of research Aabel, J.P.1, Cripps, S J.2, Jensen, A.C.3 and Picken, G.4 * Dames & Moore Group, Stavanger, Norway. 2 RF-Rogaland Research, Stavanger, Norway. 3 University of Southampton, Southampton, UK. 4 Cordah, Aberdeen, UK. Southampton Oceanography DAMES & MOORE /Centre-- A DAMES & MOORE GROUPCQMBANy I i. Preface During recent years the subject of decommissioning redundant oil and gas structures has been receiving increasing attention within the petroleum industry, regulatory authorities, pressure groups and the public in general. An increasing awareness of the technical problems that are involved, including the great expense (both to the petroleum industry and the tax payers of several nations), and the environmental and social consequences (both positive and negative), has led to the discussion and exploration of a range of, sometimes innovative, potential solutions to the problem. One such scenario that has been suggested is to use suitable, cleaned parts of some of these structures to create artificial fish attracting reefs. The Offshore Decommissioning Communications Project (ODCP) of the E&P Forum, the international petroleum industry federation, convened an Artificial Reefs / Marine Habitat Workshop on the 20 November 1996 at their offices in London. As a result of considerable interest in the potential of “rigs-to reefs”, four research and consultancy institutes that lead independent R&D work within the decommissioning of offshore structures, were commissioned to produce a report. The aim of this report, presented here, was to summarise work conducted in the field to date, evaluate what further information is required in order to reliably estimate the likely potential for offshore structures as artificial reefs in the North Sea, and propose work that would fill those gaps in knowledge. August 1997. Jens Fetter Aabel Simon Cripps Antony Jensen Gordon Picken Managing Principle Senior Scientist / Reader Senior Research Fellow Director Dames & Moore Group RF-Rogaland Research University of Cordah Southampton Kirkebakken 8, RF Decommissioning Department of Kettock Lodge, N-4012 Stavanger, Unit, Oceanography, Aberdeen Science and Norway. PO Box 2503 Southampton Technology Park, Ullandhaug, Oceanography Centre, Bridge of Don, N-4004 Stavanger, European Way, Aberdeen, AB22 8GU, Norway. Southampton, 5014 3ZH, UK. UK. Tel +47 51 89 08 50 Tel +47 51 87 52 18 Tel: +44 1703 593 428 Tel:+44 1224 414 202 Fax +47 51 89 08 49 Fax+47 51 87 52 00 Fax: +44 1703 596 642 Fax +44 1224 414 250 [email protected] [email protected] a.jensen @ soc.soton.ac.uk [email protected] pH Dames l moorf . 1. EXECUTIVE SUMMARY T 1 Executive summary The case for R&D work on North Sea artificial reefs Artificial reefs, man-made structures for attracting or protecting animals, usually fish, or for protecting the environment, have been used world-wide for many centuries. In the North Sea there is no doubt that currently operating and redundant offshore oil and gas structures do attract fish. Whilst there is some information on artificial reefs in general, platform reefs in the Mexican Gulf in particular and general information on the environment around North Sea platforms, there are insufficient data on which to reliably estimate the consequences of a rig-to-reefs programme in the special conditions of the North Sea. There are potentially many benefits that can be derived from platform reefs, for example as an aid to increased fishing yield for commercial fishermen, a means of enhancing fish stocks and protecting habitat from physical damage. In addition there may be a reduction in decommissioning costs for the oil industry (and so tax payers) and in negative environmental impacts inherent with land-based decommissioning techniques. We need however, to be able to answer questions with some degree of reliability. What are the best uses for a reef and how can it be managed within the common resource of the North Sea? What form should such a reef take? How great will be the benefits to fishermen and how can they best achieve them? Will the benefit of a reef as a protection zone against, fishing be significant either in the region, or within the fishery as a whole? To what extent would the ecosystem as a whole, and rare species in particular, benefit from such a habitat protection device? There is also the potential for negative impacts, such as loss of fishing area and changes in the ecosystem. Questions to be asked include: is the loss of access significant? Will the socio-economics of the fishermen be changed for the worse? Will the remains of the platform constitute a source of pollution on the sea bed that will detrimentally alter the ecosystem in the region? How will we assess that change? There is much talk about platform reefs in the North Sea, both positive and negative, but little data on which to base any assertions. The work proposed in this report is not a repetition of old studies, it is not purely of academic interest and it does not contain work that is not strictly relevant. The work proposed will build up a picture of how platform reefs function in the North Sea, allowing an assessment of their advantages and disadvantages, if they are likely to be a viable proposition, and if so how they can best be used. This work will need to be of a high academic quality in order to stand peer review from the oil industry, scientist and critics alike. It will be focused towards practically applicable results that will aid the decision making process. |j|jjj DAMCS & MOORE z Without such a programme of work there will be insufficient data on which decision makers, such as legislators, politicians, policy makers, environmental groups and those responsible for managing the marine habitat, can base their judgement and advice. Users of the shared marine resource and interested parties will need open, independent information in order to assess the likely benefits or problems that may result. Information, such as that to be published from this study, will go a long way to aid the assessment of the potential of platform reefs and will greatly assist communications, leading to a more open, realistic discussion based on facts rather than conjecture and suspicion. It is therefore strongly recommended by this independent project group that the proposed study programme be implemented as soon as possible in it entirety. Artificial reefs Marine artificial reefs have been defined in 1996 by the European Artificial Reef Research Network (EARRN) as: submerged structures deliberately placed on the seabed to mimic some characteristics of a natural reef. The use of artificial reefs as fishing sites has a long history. Their use for fisheries enhancement and coastal zone management is more recent. In general, the abundance and diversity of species at an artificial reef depends on suitable living conditions, a supply of recruits and a higher recruitment and immigration than mortality and emigration. Suitable living conditions may include: access to food resources, shelter from predators and currents, orientation, and normal environmental conditions that are at least within the biological tolerances of the species. Artificial reef designs Artificial reefs have been constructed from many types of material, both natural and man-made. They range, in size and material, from simple wooden constructions, to engineered steel and concrete structures, as well as "materials of opportunity" such as car tyres, old cars and abandoned offshore installations. The majority of artificial reefs have been deployed in inshore, shallow waters. In a European context there is a preference for reefs to be made from concrete, which is a prime building material. There is a philosophical opposition to recycling, on the basis that no dumping of ‘waste’ should be allowed. Distribution Japan has been one of the leading countries that have used artificial reefs as fisheries management tools, primarily fisheries yield enhancement, dedicating at least 10 % of its coastline to marine enhancement devices, and $750 million on artificial reefs in particular, between 1976 - 1988. Japan has invested considerable effort into the optimisation of reef layouts and construction. The use, by the Japanese, of artificial reef components resembling jacket structures, has increased during the last few years. OWES 4 MOORE The USA has also appreciated the opportunities of recreational fishery enhancement derived from artificial reefs and has initiated a national artificial reef programme. Each coastal state develops reefs using both engineered reefs and materials of opportunity. Despite the large investment in artificial reefs in certain countries, the ecological basis behind their function and biology is poorly understood but is actively being researched in Europe and the USA. The variety of materials used and the broad range of conditions in which reefs are deployed limits the conclusions that can be made. Nevertheless, at artificial reefs, high fish densities, biomass and catch rates, in addition to rapid colonisation, are well documented and are often found to be higher on artificial reefs than on natural reefs or randomly selected bottom controls. Rigs-to-reefs in the North Sea The concept of “rigs to reefs” is just one specialist aspect of artificial reef technology. It is generally understood to mean the use of decommissioned offshore oil and gas platforms as artificial reefs. The possibility of using platforms as reefs first arose in the Gulf of Mexico: existing manned structures off the coast of Louisiana attracted significant numbers of game fish, forming the basis of a substantial sport fishing industry. There are more than 6500 offshore oil and gas related structures world-wide.