Academic Appointments

Current Research and Scholarly Interests

Ecology, conservation, fisheries, protected species, ecosystem-based management

2016-17 Courses

Stanford Advisees

Graduate and Fellowship Programs

  • Biology (School of Humanities and Sciences) (Phd Program)

All Publications

  • Global patterns of marine mammal, seabird, and sea turtle bycatch reveal taxa-specific and cumulative megafauna hotspots PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Lewison, R. L., Crowder, L. B., Wallace, B. P., Moore, J. E., Cox, T., Zydelis, R., McDonald, S., Dimatteo, A., Dunn, D. C., Kot, C. Y., Bjorkland, R., Kelez, S., Soykan, C., Stewart, K. R., Sims, M., Boustany, A., Read, A. J., Halpin, P., Nichols, W. J., Safina, C. 2014; 111 (14): 5271-5276


    Recent research on ocean health has found large predator abundance to be a key element of ocean condition. Fisheries can impact large predator abundance directly through targeted capture and indirectly through incidental capture of nontarget species or bycatch. However, measures of the global nature of bycatch are lacking for air-breathing megafauna. We fill this knowledge gap and present a synoptic global assessment of the distribution and intensity of bycatch of seabirds, marine mammals, and sea turtles based on empirical data from the three most commonly used types of fishing gears worldwide. We identify taxa-specific hotspots of bycatch intensity and find evidence of cumulative impacts across fishing fleets and gears. This global map of bycatch illustrates where data are particularly scarce--in coastal and small-scale fisheries and ocean regions that support developed industrial fisheries and millions of small-scale fishers--and identifies fishing areas where, given the evidence of cumulative hotspots across gear and taxa, traditional species or gear-specific bycatch management and mitigation efforts may be necessary but not sufficient. Given the global distribution of bycatch and the mitigation success achieved by some fleets, the reduction of air-breathing megafauna bycatch is both an urgent and achievable conservation priority.

    View details for DOI 10.1073/pnas.1318960111

    View details for Web of Science ID 000333985200056

    View details for PubMedID 24639512

  • Using Environmental DNA to Census Marine Fishes in a Large Mesocosm PLOS ONE Kelly, R. P., Port, J. A., Yamahara, K. M., Crowder, L. B. 2014; 9 (1)


    The ocean is a soup of its resident species' genetic material, cast off in the forms of metabolic waste, shed skin cells, or damaged tissue. Sampling this environmental DNA (eDNA) is a potentially powerful means of assessing whole biological communities, a significant advance over the manual methods of environmental sampling that have historically dominated marine ecology and related fields. Here, we estimate the vertebrate fauna in a 4.5-million-liter mesocosm aquarium tank at the Monterey Bay Aquarium of known species composition by sequencing the eDNA from its constituent seawater. We find that it is generally possible to detect mitochondrial DNA of bony fishes sufficient to identify organisms to taxonomic family- or genus-level using a 106 bp fragment of the 12S ribosomal gene. Within bony fishes, we observe a low false-negative detection rate, although we did not detect the cartilaginous fishes or sea turtles present with this fragment. We find that the rank abundance of recovered eDNA sequences correlates with the abundance of corresponding species' biomass in the mesocosm, but the data in hand do not allow us to develop a quantitative relationship between biomass and eDNA abundance. Finally, we find a low false-positive rate for detection of exogenous eDNA, and we were able to diagnose non-native species' tissue in the food used to maintain the mesocosm, underscoring the sensitivity of eDNA as a technique for community-level ecological surveys. We conclude that eDNA has substantial potential to become a core tool for environmental monitoring, but that a variety of challenges remain before reliable quantitative assessments of ecological communities in the field become possible.

    View details for DOI 10.1371/journal.pone.0086175

    View details for Web of Science ID 000330235100148

    View details for PubMedID 24454960

  • Improving Ocean Management through the Use of Ecological Principles and Integrated Ecosyste Assessments BIOSCIENCE Foley, M. M., Armsby, M. H., Prahler, E. E., Caldwell, M. R., Erickson, A. L., Kittinger, J. N., Crowder, L. B., Levin, P. S. 2013; 63 (8): 619-631
  • Predicted habitat shifts of Pacific top predators in a changing climate NATURE CLIMATE CHANGE Hazen, E. L., Jorgensen, S., Rykaczewski, R. R., Bograd, S. J., Foley, D. G., Jonsen, I. D., Shaffer, S. A., Dunne, J. P., Costa, D. P., Crowder, L. B., Block, B. A. 2013; 3 (3): 234-238
  • Impacts of fisheries bycatch on marine turtle populations worldwide: toward conservation and research priorities ECOSPHERE Wallace, B. P., Kot, C. Y., DiMatteo, A. D., Lee, T., Crowder, L. B., Lewison, R. L. 2013; 4 (3)
  • Moving beyond the fished or farmed dichotomy MARINE POLICY Klinger, D. H., Turnipseed, M., Anderson, J. L., Asche, F., Crowder, L. B., Guttormsen, A. G., Halpern, B. S., O'Connor, M. I., Sagarin, R., Selkoe, K. A., Shester, G. G., Smith, M. D., Tyedmers, P. 2013; 38: 369-374
  • Cumulative human impacts on marine predators. Nature communications Maxwell, S. M., Hazen, E. L., Bograd, S. J., Halpern, B. S., Breed, G. A., Nickel, B., Teutschel, N. M., Crowder, L. B., Benson, S., Dutton, P. H., Bailey, H., Kappes, M. A., Kuhn, C. E., Weise, M. J., Mate, B., Shaffer, S. A., Hassrick, J. L., Henry, R. W., Irvine, L., McDonald, B. I., Robinson, P. W., Block, B. A., Costa, D. P. 2013; 4: 2688-?


    Stressors associated with human activities interact in complex ways to affect marine ecosystems, yet we lack spatially explicit assessments of cumulative impacts on ecologically and economically key components such as marine predators. Here we develop a metric of cumulative utilization and impact (CUI) on marine predators by combining electronic tracking data of eight protected predator species (n=685 individuals) in the California Current Ecosystem with data on 24 anthropogenic stressors. We show significant variation in CUI with some of the highest impacts within US National Marine Sanctuaries. High variation in underlying species and cumulative impact distributions means that neither alone is sufficient for effective spatial management. Instead, comprehensive management approaches accounting for both cumulative human impacts and trade-offs among multiple stressors must be applied in planning the use of marine resources.

    View details for DOI 10.1038/ncomms3688

    View details for PubMedID 24162104

  • An index to assess the health and benefits of the global ocean NATURE Halpern, B. S., Longo, C., Hardy, D., McLeod, K. L., Samhouri, J. F., Katona, S. K., Kleisner, K., Lester, S. E., O'Leary, J., Ranelletti, M., Rosenberg, A. A., Scarborough, C., Selig, E. R., Best, B. D., Brumbaugh, D. R., Chapin, F. S., Crowder, L. B., Daly, K. L., Doney, S. C., Elfes, C., Fogarty, M. J., Gaines, S. D., Jacobsen, K. I., Karrer, L. B., Leslie, H. M., Neeley, E., Pauly, D., Polasky, S., Ris, B., St Martin, K., Stone, G. S., Sumaila, U. R., Zeller, D. 2012; 488 (7413): 615-?


    The ocean plays a critical role in supporting human well-being, from providing food, livelihoods and recreational opportunities to regulating the global climate. Sustainable management aimed at maintaining the flow of a broad range of benefits from the ocean requires a comprehensive and quantitative method to measure and monitor the health of coupled human–ocean systems. We created an index comprising ten diverse public goals for a healthy coupled human–ocean system and calculated the index for every coastal country. Globally, the overall index score was 60 out of 100 (range 36–86), with developed countries generally performing better than developing countries, but with notable exceptions. Only 5% of countries scored higher than 70, whereas 32% scored lower than 50. The index provides a powerful tool to raise public awareness, direct resource management, improve policy and prioritize scientific research.

    View details for DOI 10.1038/nature11397

    View details for Web of Science ID 000308095100048

    View details for PubMedID 22895186

  • Human Dimensions of Coral Reef Social-Ecological Systems ECOLOGY AND SOCIETY Kittinger, J. N., Finkbeiner, E. M., Glazier, E. W., Crowder, L. B. 2012; 17 (4)
  • Cumulative estimates of sea turtle bycatch and mortality in USA fisheries between 1990 and 2007 BIOLOGICAL CONSERVATION Finkbeiner, E. M., Wallace, B. P., Moore, J. E., Lewison, R. L., Crowder, L. B., Read, A. J. 2011; 144 (11): 2719-2727
  • Valuing Ecosystem Services with Fishery Rents: A Lumped-Parameter Approach to Hypoxia in the Neuse River Estuary SUSTAINABILITY Smith, M. D., Crowder, L. B. 2011; 3 (11): 2229-2267

    View details for DOI 10.3390/su3112229

    View details for Web of Science ID 000208763800011

  • Guiding ecological principles for marine spatial planning MARINE POLICY Foley, M. M., Halpern, B. S., Micheli, F., Armsby, M. H., Caldwell, M. R., Crain, C. M., Prahler, E., Rohr, N., Sivas, D., Beck, M. W., Carr, M. H., Crowder, L. B., Duffy, J. E., Hacker, S. D., McLeod, K. L., Palumbi, S. R., Peterson, C. H., Regan, H. M., Ruckelshaus, M. H., Sandifer, P. A., Steneck, R. S. 2010; 34 (5): 955-966
  • Sustainability and Global Seafood SCIENCE Smith, M. D., Roheim, C. A., Crowder, L. B., Halpern, B. S., Turnipseed, M., Anderson, J. L., Asche, F., Bourillon, L., Guttormsen, A. G., Khan, A., Liguori, L. A., Mcnevin, A., O'Connor, M. I., Squires, D., Tyedmers, P., Brownstein, C., Carden, K., Klinger, D. H., Sagarin, R., Selkoe, K. A. 2010; 327 (5967): 784-786

    View details for DOI 10.1126/science.1185345

    View details for Web of Science ID 000274408300025

    View details for PubMedID 20150469

  • Small-Scale Fisheries Bycatch Jeopardizes Endangered Pacific Loggerhead Turtles PLOS ONE Peckham, S. H., Maldonado Diaz, D., Walli, A., Ruiz, G., Crowder, L. B., Nichols, W. J. 2007; 2 (10)


    Although bycatch of industrial-scale fisheries can cause declines in migratory megafauna including seabirds, marine mammals, and sea turtles, the impacts of small-scale fisheries have been largely overlooked. Small-scale fisheries occur in coastal waters worldwide, employing over 99% of the world's 51 million fishers. New telemetry data reveal that migratory megafauna frequent coastal habitats well within the range of small-scale fisheries, potentially producing high bycatch. These fisheries occur primarily in developing nations, and their documentation and management are limited or non-existent, precluding evaluation of their impacts on non-target megafauna.30 North Pacific loggerhead turtles that we satellite-tracked from 1996-2005 ranged oceanwide, but juveniles spent 70% of their time at a high use area coincident with small-scale fisheries in Baja California Sur, Mexico (BCS). We assessed loggerhead bycatch mortality in this area by partnering with local fishers to 1) observe two small-scale fleets that operated closest to the high use area and 2) through shoreline surveys for discarded carcasses. Minimum annual bycatch mortality in just these two fleets at the high use area exceeded 1000 loggerheads year(-1), rivaling that of oceanwide industrial-scale fisheries, and threatening the persistence of this critically endangered population. As a result of fisher participation in this study and a bycatch awareness campaign, a consortium of local fishers and other citizens are working to eliminate their bycatch and to establish a national loggerhead refuge.Because of the overlap of ubiquitous small-scale fisheries with newly documented high-use areas in coastal waters worldwide, our case study suggests that small-scale fisheries may be among the greatest current threats to non-target megafauna. Future research is urgently needed to quantify small-scale fisheries bycatch worldwide. Localizing coastal high use areas and mitigating bycatch in partnership with small-scale fishers may provide a crucial solution toward ensuring the persistence of vulnerable megafauna.

    View details for DOI 10.1371/journal.pone.0001041

    View details for Web of Science ID 000207456100009

    View details for PubMedID 17940605

  • Effects of stocking-up freshwater food webs TRENDS IN ECOLOGY & EVOLUTION Eby, L. A., Roach, W. J., Crowder, L. B., Stanford, J. A. 2006; 21 (10): 576-584


    The establishment of exotic game fishes to enhance recreational fisheries through authorized and unauthorized stocking into freshwater systems is a global phenomenon. Stocked fishes are often top predators that either replace native top predators or increase the species richness of top predators. Many direct effects of stocking have been documented, but the ecosystem consequences are seldom quantified. New studies increasingly document how species and community shifts influence ecosystem processes. We discuss here how predator stocking might increase top-down effects, alter nutrient cycles and decrease links between aquatic and surrounding terrestrial ecosystems. As fisheries management moves beyond species-specific utilitarian objectives to incorporate ecosystem and conservation goals, ecologists must address how common management practices alter food-web structure and subsequent ecosystem-level effects.

    View details for DOI 10.1016/j.tree.2006.06.016

    View details for Web of Science ID 000241256900008

    View details for PubMedID 16828522