Fishes with high reproductive output potential on California offshore oil and gas platforms

Abstract

Reproductive output can serve as an important metric to assess the value of a marine habitat as it combines fish densities, size at maturity, and the exponential increase of fecundity with body length. California may permit some portion of the structures of offshore oil and gas platforms to remain in place if a "net benefit to the marine environment" can be demonstrated. Here we assess habitats at 23 oil and gas platforms in terms of site- and species- specific estimates of potential reproductive output. We identified 17 fish species (15 rockfishes Sebastes spp.) that have potential reproductive output densities (no. eggs m–2) on individual platforms that were tens to hundreds of times their average on natural reefs in the study area, with the highest potential reproductive output values being observed on platforms for all but two of these species. These extreme values were typically observed in platform base habitats, and likely result from the combined effects of high levels of fish recruitment to midwater platform habitats, relatively low fishing activity on these structures, and ontogenetic habitat use (depth-specific) patterns that make some platforms better habitats for some species based on the seafloor depth where they are sited. However, spatial variability was also very high across both platform and natural reef sites, including reproductive potential for almost all focal species being zero at the majority of surveyed sites. The contribution of fish reproductive potential to the discussion of decommissioning alternatives should therefore be considered on a case-by-case basis for each platform in California.

Ecotoxicological effects of decommissioning offshore petroleum infrastructure: A systematic review

“…Leaving oil and gas structures in situ can support establishment of an ecosystem and provide potential benefits to the local faunal community, albeit one that does not reflect the original sedimentary habitat (Claisse et al, 2019;Fowler et al, 2019;Love & York, 2006;McLean, Vaughan et al, 2020;Ounanian et al, 2020). Despite this, recognizing the ecological value of decommissioned infrastructure often excludes the consideration of associated contaminants.…”

Decommissioning Research Needs for Offshore Oil and Gas Infrastructure in Australia

“…The positive effects of oil and gas structures on biodiversity and/or productivity are frequently cited to support a leave-inplace decommissioning decision. Biodiversity on and around infrastructure may increase due to the presence of hard, complex substrate, as well as enhanced recruitment and/or due to the ongoing attraction of fish and invertebrates (Macreadie et al, 2011;Love et al, 2012;McLean et al, 2017;Bull and Love, 2019;Claisse et al, 2019). Approval to leave-in-place requires operators to provide evidence that the infrastructure is of high conservation value with respect to habitats and biodiversity.…”

Forecasting the legacy of offshore oil and gas platforms on fish community structure and productivity

“…Fish density and community composition are also subject to interannual variability, which could not be fully captured in this study due to differences in survey timing and frequency between sites and habitat types. Studies of the subset of platforms that are surveyed regularly have suggested that much of the observed interannual variability at these sites is driven by rockfish recruitment dynamics and the random nature of sampling large, mobile schools , 2019, Meyer-Gutbrod et al 2019. Fish community composition and size may also exhibit some seasonal variability.…”