Background
To obtain an ecosystem-level understanding of the OCS, biological and physical databases must be integrated. To date, most ecological studies are restricted in scale due tolimited funds and information. With the completion of region-wide oceanographic and geologic surveys, it is timely to link and expand biological surveys to match the spatial scale of these physical databases. Such integration will be important to all aspects of permitting, mitigation and decommissioning decisions of the OCS. The majority of marine species observed at oil platforms and natural reefs do not reside in these habitats for their entire life history. Population connectivity within and among habitats varies according to the life history of each species, oceanographic patterns, and distribution of hard bottom. One consequence of a spatially complex life history is that impacts of a reefed platform may propagate across regions and habitats and affect other populations. Therefore, some understanding of connectivity processes, both physical and biological, must precede predictions regarding the environmental consequences of platform decommissioning alternatives. We now have sufficient knowledge to address these large scale questions. Shallow water habitats of platforms are of particular interest to BOEM because these habitats function as nurseries to commercially important juvenile rockfishes, and because potential decommissioning options eliminate this habitat. BOEM information needs thus include establishing how the removal of such habitat will impact regional environments. This study is one of a series of juvenile rockfish studies in the POCS. Previously, BOEM funded the study Assessing the Fate of Juvenile Rockfish at Offshore Platforms and Natural Reefs in the Santa Barbara Channel NSL PC-04-02, which performed a longitudinal study on the fate of juvenile rockfish if platforms were not present. During FYs 2008-2011, BOEM will support the study Spatial and Seasonal Variation in the Biomass and Size Distribution of Juvenile Fishes Associated with a Petroleum Platform off the California Coast, which will use a hydroacoustic array to collect fine-scale data on the abundance and species composition of juvenile fishes recruiting to one platform. Using the GIS, this proposed study will extrapolate this fine-scale information across the regional scale. To accomplish this, new field data has to be collected across a regional scale concurrently with the above study (recruitment in spring of 2009 and/or 2010) because of the annual natural of juvenile rockfish recruitment. The proposed study represents a critical next step in a coordinated program that extends local scale studies across the entire region of interest to OCS activities.
Data
New GIS data available from multiple sources has been modified for the purpose of characterizing the seafloor for the Regional Importance of Manmade Structures as Rockfish Nurseries study. Substrate was classified from multibeam sonar using the method of Cochrane (2008) for this study. Seafloor character derived from multibeam sonar data is available for the mainland coast within the study area from the California State Waters Mapping Program (Johnson and others, 2012; Johnson and others, 2013a; Johnson and others, 2013b; Johnson and others, 2013c). The number of substrate classes was reduced because rugosity could not be derived for all areas due to the lack of bathymetry data for other data sets used in the study. Substrate was classified from sidescan sonar data using the method of (Cochrane and Lafferty, 2002) for this study. Seafloor character derived from towed sidescan sonar data is available for the mainland coast within the study area from USGS online publications (Cochrane and others, 2003; Cochrane and others, 2005). The number of substrate classes was reduced because rugosity could not be derived for all areas due to the lack of bathymetry data for other data sets used in the study. Sea floor character was derived from interpretations of lidar data available for the mainland coast within the study area from the California State Waters Mapping Program (Johnson and others, 2012; Johnson and others, 2013a; Johnson and others, 2013b; Johnson and others, 2013c). The number of substrate classes was reduced because rugosity could not be derived for all areas. Seafloor character was derived from interpretations of air photo derived kelp distribution data available for the Santa Cruz Island (Kushner and others, 2013). The number of substrate classes was reduced because rugosity could not be derived for all areas.
References Cited
Cochrane, G.R., Nasby, N.M., Reid, J.A., Waltenberger, B., and Lee, K.M., 2003, Nearshore benthic habitat GIS for the Channel Islands National Marine Sanctuary and Southern California State Fisheries Reserves, Volume 1: U.S. Geological Survey Open-File Report 03-85, http://pubs.usgs.gov/of/2003/0085/.
Cochrane, G.R., and Lafferty, K.D., 2002, Use of acoustic classification of sidescan sonar data for mapping benthic habitat in the Northern Channel Islands, California: Continental Shelf Research, v. 22, p. 683-690.
Cochrane, G.R., Conrad, J.E., Reid, J.A., Fangman, S., and Golden, N., 2005, The nearshore benthic habitat GIS for the Channel Islands National Marine Sanctuary and Southern California State Fisheries Reserves, Volume II: U.S. Geological Survey, Open-File Report 2005-1170, http://pubs.usgs.gov/of/2005/1170/.
Cochrane, G.R., 2008, Video-supervised classification of sonar data for mapping seafloor habitat, in Reynolds, J.R., and Greene, H.G., eds., Marine habitat mapping technology for Alaska: Fairbanks, University of Alaska, Alaska Sea Grant College Program, p. 185-194, accessed April 5, 2011, at http://doc.nprb.org/web/research/research%20pubs/615_habitat_mapping_workshop/Individual%20Chapters%20High-Res/Ch13%20Cochrane.pdf.
Kushner D.J., Rassweiler, A., McLaughlin, J.P., and Lafferty, K.D., 2013, A multi-decade time series of kelp forest community structure at the California channel islands: Ecology, v. 94, p. 2,655.
Map 3281, 45 p., 11 sheets, scale 1:24,000, https://dx.doi.org/10.3133/sim3281/.
Johnson, S.Y., Dartnell, P., Cochrane, G.R., Golden, N.E., Phillips, E.L., Ritchie, A.C., Kvitek, R.G., Greene, H.G., Endris, C.A., Seitz, G.G., Sliter, R.W., Erdey, M.D., Wong, F.L., Gutierrez, C.I., Krigsman, L.M., Draut, A.E., and Hart, P.E. (S.Y. Johnson and S.A. Cochran, eds.), 2013b, California State Waters Map Series—Offshore of Carpinteria, California: U.S. Geological Survey Scientific Investigations Map 3261, 42 p., 10 sheets, scale 1:24,000, https://pubs.usgs.gov/sim/3261/.
Johnson, S.Y., Dartnell, P., Cochrane, G.R., Golden, N.E., Phillips, E.L., Ritchie, A.C., Kvitek, R.G., Greene, H.G., Krigsman, L.M., Endris, C.A., Clahan, K.B., Sliter, R.W., Wong, F.L., Yoklavich, M.M., and Normark, W.R. (S.Y. Johnson, ed.), 2012, California State Waters Map Series—Hueneme Canyon and Vicinity, California: U.S. Geological Survey Scientific Investigations Map 3225, 41 p., 12 sheets, scale 1:24,000, https://pubs.usgs.gov/sim/3225/.
Johnson, S.Y., Dartnell, P., Cochrane, G.R., Golden, N.E., Phillips, E.L., Ritchie, A.C., Kvitek, R.G., Greene, H.G., Krigsman, L.M., Endris, C.A., Seitz, G.G., Gutierrez, C.I., Sliter, R.W., Erdey, M.D., Wong, F.L., Yoklavich, M.M., Draut, A.E., and Hart, P.E. (S.Y. Johnson and S.A. Cochran, eds.), 2013c, California State Waters Map Series—Offshore of Ventura, California: U.S. Geological Survey Scientific Investigations Map 3254, pamphlet 42 p., 11 sheets, scale 1:24,000, https://pubs.usgs.gov/sim/3254/.
