Critical to formulation of appropriate decommissioning policy is an understanding of the ecological, economic and social consequences of different decommissioning options and identification of the mechanisms by which such information is incorporated, or not, into legislation and public policy. Perhaps the most important ecological consequence of abandoning POCS facilities is a potential change in regional fish production (the biomass of fish accrued per year), which may in turn influence yields to fisheries. Hard substratum reefs represent a small fraction of the available offshore habitat in California, but are sites of high fish production. However, prior to this study, only one study provided quantitative estimates of species composition and abundance of fishes at a single platform off southern California.

Objective 1:
Ascertaining the ecological and related economic effects of total or partial removal of offshore structures

Quantitative description of fish assemblages on natural reefs and offshore structures.

One objective of this study has been to quantify the species and sizes of fishes associated with platforms and natural reefs. Such information is required to determine what species and life stages might be influenced by the various decommissioning options. Do fish recruit to each habitat type from the plankton (as larvae) or migrate on to one habitat type from the other as older stages (benthic juveniles and adults)? Comparison of fishes between platforms and natural reefs provides information on what stages use the two habitat types. Patterns of fish sizes over time can also provide information on how long fishes associate with each habitat type and how well they grow and survive. Such information is critical to understanding the relative value of natural reefs and platforms as fish habitat.

Fish assemblages associated with shallow (< 33m) portions of six production platforms (Hogan, Houchin, Henry, A, B, and C) and three shallow natural reefs were sampled monthly from May through October, 1997 using diver surveys. Deeper (>33m) portions of these platforms and 1-2 deeper natural reefs were surveyed during June and September with the remotely operated vehicle (ROV) provided to us by the Santa Barbara City College. Mechanical failure of the ROV prohibited sampling half of the six platforms in September and any of the fall sampling period. Surveys conducted by divers involved estimates of the density and size of individuals of each species along 2 m wide x 2 m tall belt transects at predetermined locations and depths. A second diver sampled the same transects using an underwater video system. The video system (equipped with parallel lasers for estimating fish length) was used to increase the sample size of fish lengths and provide a standard for comparing samples with ROV video at depth. Belt transects of similar dimensions were sampled with the ROV while an observer logged the depth and location of transects, and identified fish species. Diver surveys of natural reefs also included quantification of habitat variables (e.g., substratum type and relief, epibenthic cover, density and size of macroalgae, temperature and visibility) that might explain patterns of species abundance.

Observers (technicians and undergraduate volunteers) were trained to determine the portions of platforms sampled (i.e. transect identification), species identification, size estimates (using laser images), and fish enumeration. Quantification, species identification, and data transcription from the diver video tapes to spreadsheets (Microsoft Excel and Access) for the 1997 sampling period is in progress. Quantification, species identification, and data transcription from the ROV video tapes to spreadsheets for the 1997 sampling period is completed. Dimensions of all platform structures sampled for all three years were calculated and incorporated into the databases for density calculations. Technicians are reviewing all three years of ROV video and the remaining 1.5 years of diver video for laser assessed estimates of fish length. Some preliminary findings outlined below are highly consistent with results from previous years.

1. During the 1997 sampling season, a total of 63 taxa (mostly species) of fish were recorded by the diver and ROV surveys. Of these, 18 taxa were only seen on natural reefs, 13 were seen only on platforms, and 32 were common to both habitats. Consistent with the previous two yeas of sampling, these data indicate that those species encountered only on natural reefs, mostly surf perches and some kelp-associated species would be influenced little by the presence or absence of oil platforms in this region. Those species encountered only or primarily on platforms (mostly juvenile and adult rockfishes) are likely to be most strongly influenced by the different platform decommissioning options. Many species that co-occurred at both platforms and natural reefs were often far more abundant in one habitat or the other (see below).

2. Two important species (i.e. recreationally exploited) which were far more abundant on natural reefs include the sand bass and the kelpbass. These data again suggest that regional populations of these two species would be influenced negligibly by the presence, alteration, or absence of offshore structures. In contrast, several rockfish species were far more abundant on platforms than the natural reefs we sampled. These species include the copper rockfish, blue rockfish, bocaccio, and olive rockfish, all of which are of economic importance to the local recreation or commercial fishery.

3. Juvenile rockfishes (<10 cm) of several species were the most common fish species on the six platforms and were far more abundant on platforms than on the natural reefs we sampled. These species can be categorized into three species complexes based on their depth distribution and affinity to reef structure (i.e. demersal species that rest on the reef versus species that aggregate in the water away from the reef structure). The first group consists of shallow dwelling demersal species (kelp rockfish, gopher rockfish, black & yellow rockfish, and copper rockfish). Recently settled recruits (2-4 cm SL) of these species occurred at the shallower levels sampled (10 and 20 m) and less abundant at deeper depths. In contrast, recruits (4-8 cm SL) of the mid-water aggregating rockfishes (widow, olive, boccacio) were more abundant at deeper levels (30 and 40 m). In sharp contrast to previous years, ROV video sighted large numbers of a deep-water demersal species (including halfbanded rockfish) on the bottom at the base of the platforms.

4. These patterns of rockfish recruitment have some important implications for the effects of different decommissioning approaches. Firstly, platforms may be sites of increased recruitment of rockfishes in this region of the Santa Barbara Channel. Thus, complete removal of platforms might reduce regional levels of rockfish recruitment, depending on the fate of these recruits in the absence of these structures. Secondly, removal of the upper portion of platforms (i.e., "topping" or "toppling") may reduce recruitment of those rockfish species that recruit to that section (i.e. the shallow dwelling demersal species listed above). In contrast, those species that recruit directly to the lower portions of the platforms (20-30 m and deeper) would likely continue to recruit to "topped" or "toppled" platforms.

5. Two other patterns of rockfish recruitment are notable. Most species were patchily distributed among platforms, and we are examining data from this year to determine if these differences among platforms are consistent from year-to-year or if instead they reflect variation in the delivery of larvae resulting in inconsistent spatial patterns over time. This is important as it pertains to the constancy of a platform's role as recruitment habitat through time. A second pattern is the recruitment of a species at depths shallower than those occupied by older stages (older juveniles and adults). This result is important because the greater abundance of older rockfish may diminish if recruitment of that species is curtailed by the removal of the upper portions of platforms. This effect depends on the extent to which the abundance of older stages is reliant on recruitment to that site versus immigration of older stages from other sites.

6. Another pattern consistent among years is substantially higher numbers of very small kelp bass (< 10 cm) on natural reefs compared to platforms. However, numbers of large kelpbass are more comparable between platforms and natural reefs. This suggests that platforms may not be suitable settlement habitat for larval kelp bass, but that older stages may migrate onto platforms after first recruiting elsewhere. This hypothesis is corroborated by the higher movement of tagged kelp bass among reefs than other species.

7. There are high densities of several smaller fish species on platforms that presumably provide a food base for the larger economically important species. Some of the species occur at densities that are equivalent to (e.g., senorita, blacksmith), or higher than their densities on natural reefs nearby (e.g., half-moon).

Fundamental to understanding the net contribution of local populations to regional production is information on the size-specific rate of migration of fishes among local, reef-associated populations. In the context of platform decommissioning, knowledge of the net direction and rate of transfer of biomass between platforms and natural reefs is crucial. For example if fish recruit to natural reefs and eventually migrate to platforms, accumulation of fish biomass on platforms would be incorrectly attributed to production at the platform habitat. Conversely, if platforms provide recruitment habitat for fish that eventually migrate to natural reefs, the contribution of platforms to regional production may be grossly underestimated by simply measuring production in the two habitats. Movement information is also important to determine whether the loss of fish at a site is due to emigration rather than mortality. Therefore, we have conducted a tagging study determine how much and what direction (from platforms to reefs or vice versa) fish move, the rate of that movement, and net direction of exchange.

We have tagged 500 fish and recaptured 60. Ten of these fish were returned in the past year. This high return rate (10%) is attributable to (1) the excellent cooperation by sport fishers that have called us with information on the fish they caught, and (2) limited movement of many of the tagged fish. The pattern remains similar to past years; of the fish recaught, roughly 75% were caught where they were tagged, suggesting that many of the species tagged (mostly rockfishes) remain on the reefs they were tagged at. Of course, it is not clear how much movement occurs by the many fish that were not recaptured, but we hope to continue to collect information on those individuals in the future. Some species contributed highly to the individuals that moved from reefs they were tagged at; particularly barred sand bass and kelp bass. This greater movement of kelp bass, relative to other species, helps to explain why we see many adults on platforms, but no young recruits. These data strongly suggest that a species like this is attracted to platforms, having recruited as young elsewhere, rather than recruiting to and remaining on the platforms.

Problems Encountered. Mechanical failure of the ROV precluded a full set of sampling (1.5 of 3 sampling periods) of deep portions of platforms and natural reefs.

Objective 2:
Examining whether and how scientific information has influenced prior abandonment policy

Social scientists have focused on the legal, political and institutional issues associated with OCS oil and gas exploration and development (e.g., Cicin-Sain and Knecht 1987; Hershman et al. 1988; Farrow 1990; Lester 1991; Lima 1994; Freudenberg and Gramling 1994; Gramling 1996). From 1896 to 1970, Lima (1994) identifies six periods of technological development of Pacific OCS oil and gas activities. Lima (1994) shows that California and local government was generally supportive of development during the early stage of offshore drilling off Santa Barbara. After 1966, however, renewed jurisdictional disputes between the state and federal government and conflicts between offshore development and competing land uses heightened community concerns over development. Since 1970, public support has generally declined (Smith and Garcia 1994). In OCS oil and gas policy-making, this decline in public support is a byproduct of the public perceptions of risk associated with development and the "pull of local control" over proposals for offshore oil and gas development. This decline in support for offshore oil and gas development is exemplified by the over 15 initiatives that have been passed by counties and cities to restrict the placement of onshore OCS support facilities along California's coast. These various place-based initiatives have affected the politics of OCS oil and gas activities, and are likely to affect the process of decommissioning policy making as well.

The southern and central regions of California are rapidly entering a new era of OCS oil and gas activity. Decommissioning of offshore oil and gas facilities is rapidly becoming an issue of concern. The ultimate cultural and ecological impacts of decommissioning OCS oil and gas structures is not well understood by scientists, policy makers or the general public. The NRC (1985b) estimates that the cumulative costs for removal of all platforms in the OCS could total $2.9 billion by 2005 and $9.9 billion by 2020 while the GAO (1994) estimates the total decommissioning costs at $4.4 billion. The GAO (1994) reviewed offshore structure removal operations and concluded that the MMS needs to better understand the risk of environmental damage posed by certain decommissioning practices, such as the use of explosives as a removal technique. What is certain is that the economic costs of decommissioning on the oil industry will be significant.

With a focus on the Gulf, the National Fishing Enhancement Act of 1984 called for the development of a National Artificial Reef Plan. Under the direction of the National Marine Fisheries Service, this plan: 1) established general guidelines for artificial reef materials, siting and design; 2) identified oil and gas structures as excellent material for developing offshore reefs of opportunity; 3) charged coastal states with the primary responsibility for developing and implementing site specific artificial reef plans; 4) assigned the Army Corps of Engineers the responsibility of developing artificial reef regulations and for permitting artificial reef projects in the waters of the US; and 5) limited liability of approved reef sponsors who complied with the terms and conditions of artificial reef permits.

From 1987-1995, of the over 941 platforms removed from Louisiana and Texas waters, 90 platforms or approximately 10% were transformed into artificial reefs. The primary purpose of the National Artificial Reef Plan is to enhance the social and economic values associated with the Gulf's sports and commercial fisheries, not the ecological values that may be associated with these structures (e.g., enhancement of local and regional biodiversity).

The human and ecological character of the Gulf region is much different than that of California. Learning from the Gulf experience is important, but one should recognize that the diverse bioregional history (which includes ecology and culture, natural and human history) of the Gulf is very different from California's bioregions. For example, California's diverse cultural and social systems are qualitatively and quantitatively different than those that exist in the Gulf region. As the NRC (1992: 68) states, "[T]he definitions of OCS issues and problems--and solutions to them--are as much based on those persons' perceptions, biases, culture, and experience as are those of any affected person or community". Robert Gramling (1996: 149) points out in his analysis of offshore oil development in the Gulf, "Because of divergent processes over time and different socioeconomic factors...they are fundamentally different...social realities." Freudenberg and Gramling (1994: 75) show that, in Louisiana, offshore drilling evolved in a social environment characterized by a low level of environmental concern. The social reality and environmental concern of California will likely shape the politics of decommissioning policy making in different ways.

Given the complexity and intergovernmental/non governmental character of decommissioning policy making, McGinnis has identified three strategies for integrating ecological information into decommissioning policy making:

First, policy makers should adopt a case- or region-specific approach to reviewing the cultural and ecological importance of each platform and structure. Ecological information is most useful when it does not try to predict complex interactions among many species over large areas, but instead attempts to predict what will happen for only subsets of species in a particular case (e.g., deep dwelling rockfishes like bocaccio and widow rockfish). Moreover, policy makers should avoid programmatic EIRs which tend to cover broad policy areas (i.e., several geographical areas and platforms). Individual or subsets of platforms should be evaluated as a separate part of a regional oceanographic and ecological system.

Second, if a rigs-to-reef program is adopted as an alternative to complete removal, policy makers adopt an approach akin to a living permit, which supports values of adaptive decision making. Adaptive decision making views decision making and planning as an ongoing experiment that supports the life-producing character of an ecological system, not merely socioeconomic values.

Third, policy making should be based on cooperative approaches that can coordinate the values and interests of a broad range of government and non-government participants. Policy makers should recognize that there are a range of values associated with ecological information pertaining to the ocean and coastal zone, including scientific, aesthetic, life-giving, recreational, and economic values. Many of these values are shared by the community.

McGinnis is completing a revision of a paper which was included in a draft form in the proceedings of California and the World's Ocean '97 for journal publication. This paper will include an extended review of the role of science in decommissioning, and will describe a number of policy recommendations to strengthen the integration of scientific information, sociocultural and contextual values and factors. He is also planning to submit a grant proposal to continue this research on decommissioning policy options.

Future plans:

Our efforts are in-depth are focused now on in-depth analysis of the data collected over the past 3 years. We will also continue our efforts to estimate the contribution of the platforms to regional abundance of hard bottom habitat and to the local recreational and commercial fisheries. We will continue to collect tag returns to refine our estimates of fish movement in the area. Our primary emphasis will be directed at generating publications from this project.