U.S. West Coast Groundfish Bottom Trawl Survey
The West Coast Groundfish Bottom Trawl Survey (WCGBTS) is a key source of fishery-independent data used for stock assessments and groundfish management.
We ensure the sustainability of marine fisheries by providing a time series of catch and biological data of groundfish populations to stock assessors and fisheries managers.
We collect data on the abundance, spatial distribution, sex, length, maturity, weight, and age of groundfish in trawlable shelf and slope habitats along the U.S. West Coast. Our surveys generate a unique blend of data supporting agency priorities to develop Next Generation Stock Assessments. Since 2003, our survey data have informed virtually every groundfish stock assessment and contributed to the successful management of west coast stocks.
A lone Pacific halibut on low-relief, trawlable habitat. Photo: NOAA Fisheries
Fishery biologists and deckhands working up a big tow on the F/V Excalibur. All catches
are first divided into baskets by species. Photo: NOAA Fisheries
West Coast Groundfish Bottom Trawl Survey Background
The Survey occurs from May to October each year. Our coverage extends from Cape Flattery, Washington (U.S. - Canada border) south to the U.S.-Mexico border. We cover this area twice each year using chartered commercial fishing vessels and an Aberdeen-style trawl net. The Survey uses a stratified random sampling design and adheres to strictly standardized trawl gear and rigging specifications. More methods information can be found in the 2017 Trawl Survey Technical Memorandum (PDF, 38 pages.)
We check catch and haul-related information at sea. Vessels are equipped with modern instrumentation to monitor trawl performance and net position, including bottom contact sensors, global positioning systems (GPS), multiple depth sounders, and radar. A variety of oceanographic sensors are attached directly to the trawl net to collect water column profiles of temperature, salinity, turbidity, fluorescence, light, and dissolved oxygen for each haul at depth.
We encounter about 90 commercially fished stocks, including the following species categories:
- Sharks and skates.
- Flatfishes.
- Rockfishes and thornyheads.
- Roundfishes (lingcod, greenlings, and sablefish).
We sort, measure and weigh all captured fish and invertebrate species. Doing so ensures that data are accurate and current annually.
We collect the following biological samples on a subset of species for further analysis:
- Otoliths and other structures (vertebrae, fin rays, spines) are for ageing
- Finclips for genetics
- Stomach contents and tissue samples for stable isotope and diet analysis
- Gonads for maturity and reproductive analysis
Volunteering for the Survey
Each year volunteers from academic institutions and other State and Federal agencies assist with biological sampling and research operations at sea. Learn more about volunteering with NOAA biologists on the survey.
Supporting Research
In addition to the Survey's primary objective of collecting fishery-independent data, we also conduct a variety of supporting research in the region.
Groundfish Life-History Studies
Our fisheries scientists collaborate with a wide range of research institutions, universities, and state and federal agencies to better understand groundfishes' life-history. We have conducted many age-and-growth, diet, maturity, physiology, and distribution studies on rockfishes, sharks, rays, and other deep-sea species. We are interested in tracking how these life-histories change over space and time, particularly in response to long and short-term oceanographic trends, seafloor habitat types, and fishing intensity. As of 2020, data from the Survey has contributed to more than 20 published groundfish life-history studies.
Diet Studies and Trophic Ecology
We also research the prey composition, and foraging groundfishes' habits to identify their role in the food web. Scientists use this information in a wide range of applications, from life history studies and trophic cascades to integrated ecosystem assessments. Diet information is particularly useful for improving our understanding of how anomalous events, including El Niño, warm blobs, and seasonal hypoxia, can influence food webs and fisheries. Learn more about our West Coast Groundfish Diet Research.
Effect of Hypoxic (Low Oxygen) Zones on Fish Distribution
Naturally occurring low oxygen areas, known as oxygen minimum zones, are expanding due to changing deep-sea oceanographic processes. Hypoxia can be especially detrimental to groundfishes living near the sea floor, resulting in high mortality rates and shifting species distributions.
Genetics and Discovery of New Species
We collect genetic samples from fish and invertebrates for ongoing research on deep-sea coral taxonomy, rockfish speciation, and coastwide population structure. Genetic analysis lets us distinguish new species from existing ones, and helps decide what species we should protect under the Endangered Species Act (ESA). The use of genetics has enabled us to delist from the ESA previously overfished species (i.e., canary rockfish). Genetic samples support many research collaborations at the Northwest Fisheries Science Center and elsewhere.
Long-Term Ecosystem Assessment of the Northeast Pacific
We have improved our understanding of ecosystem-level dynamics within the California Current Ecosystem because of the Survey's long time series and our collection of oceanographic and habitat data. In 2019, we teamed up with ecosystem scientists, oceanographers, and economists to create the California Current Integrated Ecosystem Assessment (CCIEA). This collaboration allows us to track climate patterns, quantify fishery response, and project future conditions.
Industry Partners
- F/V Excalibur, Newport, Oregon: Owner/operator: Captain Mike Retherford Sr. with Captain Mike Retherford Jr., Captain Chris Retherford and Captain Kyle Retherford
- F/V Noah's Ark, Harbor, Oregon: Owner: David Pettinger; Captain: Curt Meng
- F/V Last Straw, Newport, Oregon: Owner/operator: Captain Brett Hearne/ Captain Wade Hearne
- F/V Ms Julie, Coos Bay, Oregon: Owner/operator: Captain Rex Leach, Captain Cody Leach
Research Partners
West Coast commercial fishermen, Oregon State University, Moss Landings Marine Research Laboratory, University of Washington.
- F/V Excalibur, Newport, Oregon: Owner/operator: Captain Mike Retherford Sr. with Captain Mi ke Retherford Jr., Captain Chris Retherford and Captain Kyle Retherford
- F/V Noah's Ark, Harbor, Oregon: Owner: David Pettinger; Captain: Curt Meng
- F/V Last Straw, Newport, Oregon: Owner/operator: Captain Brett Hearne/ Captain Wade Hearne
- F/V Ms Julie, Coos Bay, Oregon: Owner/operator: Captain Rex Leach, Captain Cody Leach
Contacts
Aimee Keller, Ph.D., Fisheries Research Surveys Supervisor
Aimee.Keller@noaa.gov
Project Team:
Aimee Keller, Northwest Fisheries Science Center
Keith Bosley, Northwest Fisheries Science Center
Dan Kamikawa, Northwest Fisheries Science Center
Victor Simon, Northwest Fisheries Science Center
John Harms, Northwest Fisheries Science Center
John Buchanan, Northwest Fisheries Science Center
Melissa Head, Northwest Fisheries Science Center
Aaron Chappell, Northwest Fisheries Science Center
Doug Draper, Northwest Fisheries Science Center
Peter Frey, Northwest Fisheries Science Center
Laurel Lam, Northwest Fisheries Science Center, Pacific States Marine Fisheries Commission
Photo Gallery
See more photos taken on the U.S. West Coast Groundfish Bottom Trawl Survey.
More Information
2017 Trawl Survey Technical Memorandum (PDF, 38 pages)
Reeling to Rebuilding: Success for West Coast Groundfish Fisheries
Publications
Bosley, K.L., Bosley, K.M., Keller, A.A. and Whitmire, C. accepted. Relating groundfish diversity and biomass to structure-forming invertebrates in the Northeast Pacific Ocean: an exploration of catch data from a fishery-independent trawl survey. Marine Ecology Progress Series.
Harvell, C.D., Montecino-Latorre, D., Caldwell, J.M., Burt, J.M., Bosley, K., Keller, A., Heron, S.F., Salomon, A.K., Lee, L., Pontier, O., Pattengill- Semmens, C. and Gaydos, J.K. 2019. Disease epidemic and a marine heatwave are associated with the continental-scale collapse of a pivotal predator (Pycnopodia helianthoides). Science Advances 5: eaau7042.
Harvey, C., N. Garfield, G. Williams, N. Tolimieri, I. Schroeder, K. Andrews, K. Barnas, E. Bjorkstedt, S. Bograd, R. Brodeur, B. Burke, J. Cope, A. Coyne, L. deWitt, J. Dowell, J. Field, J. Fisher, P. Frey, T. Good, C. Greene, E. Hazen, D. Holland, M. Hunter, K. Jacobson, M. Jacox, C. Juhasz, I. Kaplan, S. Kasperski, D. Lawson, A. Leising, A. Manderson, S. Melin, S. Moore, C. Morgan, B. Muhling, S. Munsch, K. Norman, R. Robertson, L. Rogers-Bennett, K. Sakuma, J. Samhouri, R. Selden, S. Siedlecki, K. Somers, W. Sydeman, A. Thompson, J. Thorson, D. Tommasi, V. Trainer, A. Varney, B. Wells, C. Whitmire, M. Williams, T. Williams, J. Zamon, and S. Zeman. 2019. Ecosystem Status Report of the California Current for 2019: A Summary of Ecosystem Indicators Compiled by the California Current Integrated Ecosystem Assessment Team (CCEIA). U.S. Department of Commerce, NOAA Technical Memorandum NMFS-NWFSC-149.
Li, L., A. Hollowed, E. Cokelet, S. Barbeaux, N. Bond, A. Keller, J. King, M. McClure, W. Palsson, P. Stabeno, and Q. Yang. 2019. Subregional differences in groundfish distributional responses to anomalous ocean bottom temperatures in the northeast Pacific. Global Change Biology 25: 2560-2575.
Kamikawa, D. 2019. Key to Caristiidae in: Miller and Lea's Guide to the Coastal Marine Fishes of California, Passarelli J. and Love, M. (eds.) new edition.
Keller, A.A., Harms, J., Wallace, J., Benante, J., Jones, C. and Chappell, A. 2019. Changes in long-lived rockfishes after more than a decade of protection within California’s largest marine reserve. Marine Ecology Progress Series. 623: 175-193.
Keller, A.A., Frey, P., Wallace, J., Head, M.A., Wetzel, C.R., Cope, J.M. and Harms. J.H. 2018. Canary rockfishes (Sebastes pinniger) return from the brink: catch, distribution and life history along the U.S. west coast (Washington to California). Marine Ecology Progress Series, 599: 181 – 200 doi:10.3354/meps12603.
Frey, P.H., A.A. Keller, V. Simon. 2017. Dynamic population trends observed in the deep-living Pacific flatnose, Antimora microlepis, on the U.S. West Coast. Deep Sea Research Part I: Oceanographic Research. Deep-Sea Research, I. 122: 105-112.
Bosley, K.M., Copeman, L.A., Dumbauld, B.R., & K.L. Bosley. 2017. Identification of burrowing shrimp food sources along an estuarine gradient using fatty acid analysis and stable isotope ratios. Estuaries and Coasts, 40(4), 1113-1130.
Keller, A.A., Wallace, J.R. and Methot, R.D. 2017. The Northwest Fisheries Science Center’s West Coast Groundfish Bottom Trawl Survey: Survey History, Design, and Description. U.S. Department of Commerce, NOAA Technical Memorandum, NMFS-NWFSC-136, 47 pp.
Keller, A.A., L. Ciannelli, W.W. Wakefield, V.H. Simon, J.A. Barth, S.D. Pierce. 2017. Species-specific responses of demersal fishes to near-bottom oxygen levels within the California Current large marine ecosystem. Marine Ecology Progress Series, (568)151-173. doi:https://doi.org/10.3354/meps12066
Everett, M. V., L.K. Park, E. A. Berntson, A. Elz, C. Whitmire, A.A. Keller, M.E. Clarke. 2016. Large-scale genotyping-by-sequencing indicates high levels of gene flow in the deep-sea octocoral Swiftia simplex (Nutting 1909) on the west coast of the United States. PLoS ONE. 11(10): e0165279. doi:10.1371/journal.pone.0165279
Head, M.A., G.L. Stokes, J. T. Thorson, A.A. Keller. 2016. Techniques for improving estimates of maturity ogives in groundfish using double-reads and measurement error models. Fisheries Research, 179: 251-258.
Keller, A., J.C. Buchanan, E. Steiner, D. Draper, A. Chappell, P.H. Frey, M.A. Head. 2016. Size at maturity for grooved Tanner crab (Chionoecetes tanneri) along the U.S. west coast (Washington to California). Fisheries Oceanography, 25(3):292-305. doi:doi:10.1111/fog.12155
Ono, K., Shelton, A.O., Ward, E.J., Thorson, J., Feist, B.E. and Hilborn, R. 2016. Space-time investigation of the effects of fishing on fish populations. Ecological Applications, 26(2): 392 – 406, https://doi.org/10.1890/14 – 1874.
Bradburn, J.M. and A.A. Keller. 2015. The effect of light on the catch rate of four species from the Northwest Fisheries Science Center’s west coast groundfish bottom trawl survey (2009 – 2010). Fish. Res. 164:193-200.
Drazen, J. C., J.R. Friedman, N.E. Condon, E. J. Aus, M.E. Gerringer, A.A. Keller, M. E. Clarke. 2015. Enzyme activities of demersal fishes from the shelf to the abyssal plain. Deep Sea Research Part I: Oceanographic Research. Deep-Sea Research I. 100:117–126.
Ebert, D.A., Pien, C. and Kamikawa, D. 2015. Confirmation of the cookiecutter shark, Isistius brasiliensis, from the eastern North Pacific Ocean (Chondrichthyes: Squaliformes: Dalatiidae). Marine Biodiversity Records 8: e118 (3 pages). DOI: https://dx.doi.org/10.1017/S1755267215000962.
Frey, P. H., M.A. Head, A. Keller. 2015. Maturity and growth of darkblotched rockfish, Sebastes crameri, along the U.S. west coast. Environmental Biology of Fishes, 98:2353-2365.
Keller, A., L. Ciannelli, W. W. Wakefield, V. Simon, J.A. Barth, S. D. Pierce. 2015. Occurrence of demersal fishes in relation to near-bottom oxygen levels within the California current large marine ecosystem. Fisheries Oceanography, 24(2):162-176. doi:10.1111/fog.12100.
Bosley, K. L., T.W. Miller, R.D. Brodeur, K.M. Bosley, A.L. Van Gaest, A. Elz. 2014. Feeding ecology of juvenile rockfishes off Oregon and Washington based on stomach content and stable isotope analyses. Marine Biology, 161(10):2381-2393.
Brodeur, R. D., J. C. Buchanan, R. L. Emmett. 2014. Pelagic and demersal fish predators on juvenile and adult forage fishes in the California Current: spatial and temporal variations. California Cooperative Oceanic Fisheries Investigations Reports, 55: 96–116.
Bryan, D.R., K.L. Bosley, A.C. Hicks, M.A. Haltuch, W.W. Wakefield. 2014. Quantitative video analysis of flatfish herding behavior and impact on effective area swept of a survey trawl. Fisheries Research, Volume 154 (June 2014):120-126.
Ebert, D.A., Knuckey, J. and D. Kamikawa. 2014. First eastern North Pacific record of the velvet dogfish, Zameus squamulosus (Chondrichthyes: Squaliformes: Somniosidae). Marine Biodiversity Records, 7: e48, 1-3. doi: 10.1017/S1755267214000499.
Head, M.A., A.A. Keller, M.J. Bradburn. 2014. Maturity and growth of sablefish, Anoplopoma fimbria, along the U.S. West Coast. Fisheries Research, 159: 56-67. DOI: 10.1016/j.fishres.2014.05.007
Hess, J.E., Chittaro, P., Elz, A., Gilbert-Horvath, E.A., Simon, V.H. and Garza, J.C. 2014. Cryptic population structure near Point Conception, CA in the severely depleted cowcod, Sebastes levi. Can. J. Fish. Aquat. Sci. 71: 81-92.
Keller, A.A., Wakefield, W.W., Whitmire, C.E., Horness, B.H., Bellman, M.A. and K.L. Bosley. 2014. Distribution of demersal fishes along the U.S. west coast (Canada to Mexico) in relation to the spatial fishing closures (2003 – 2011). Mar. Ecol. Prog. Ser. 501:169-190.
Keller, A.A., Bradburn, M.J. and Simon, V.H. 2013. Shifts in condition and distribution of eastern North Pacific flatfish along the U.S. west coast (2003 – 2010). Deep-Sea Research I, 77: 23 – 35.
Tolimieri, N., Samhouri, J. F., Simon, V., Feist, B. E., & Levin, P. S. 2013. Linking the trophic fingerprint of groundfishes to ecosystem structure and function in the California Current. Ecosystems, 16(7), 1216-1229.
Bryan, D., Jacobson, K.C. and Buchanan, J. 2012. Recent increase in Nybelinia surmenicola prevalence and intensity in Pacific hake (Merluccius productus) off the United States west coast. Journal of Parasitology 98: 85 – 92.
Keller, A.A., Harms, J. and Buchanan, J.C. 2012. Distribution, biomass and size of grooved Tanner crabs (Chionoecetes tanneri) from annual bottom trawl surveys (2003-2010) along the U.S. west coast (Washington to California). Deep Sea Research Part I: Oceanographic Research, 67: 44 – 54.
Keller, A.A., Molton, K.J., Hicks, A.C., Haltuch, M.A. and Wetzel, C.R. 2012. Variation in age and growth of greenstriped rockfish (Sebastes elongatus) along the U.S. West Coast (Washington to California). Fisheries Research 107: 80 – 88.
Keller, A.A., Wallace, J.R., Horness, B.H., Hamel, O.S. and Stewart, I.J. 2012. Variations in Eastern North Pacific demersal fish biomass based on the U.S. West Coast Groundfish Bottom Trawl Survey (2003-2010). Fishery Bulletin, 110: 63 – 80.
Chittaro, P.M., Kaplan, I.C., Keller, A.A. and Levin, P.S. 2010. Trade-offs between species conservation and the size of marine protected areas. Conservation Biology, 24(1): 197 – 206. doi:10.1111/j.1523-1739.2009.01323.x.
Keller, A.A., Fruh, E.L., Johnson, M. M., Simon, V., & McGourty, C. 2010. Distribution and abundance of anthropogenic marine debris along the shelf and slope of the US West Coast. Marine pollution bulletin, 60(5), 692-700.
Stewart, I.J., Keller, A.A., Fruh, E.L., Simon, V.H., & Horness, B. H. 2010. Throwing in the towel: When do adverse conditions dictate a weather day during a bottom trawl survey?. Fisheries research, 102(1-2), 130-140.
Keller, A.A., Simon, V., Chan, F., Wakefield, W.W., Clarke, M. E., Barth, J.A., & Fruh, E.L. 2010. Demersal fish and invertebrate biomass in relation to an offshore hypoxic zone along the US West Coast. Fisheries Oceanography, 19(1), 76-87.