PhD Research - Sarah Valencia

Sarah’s dissertation research examines the costs and benefits of integrating no-take marine reserves into fisheries management, with a particular emphasis on improving the management of small-scale and data-poor fisheries. Many of these fisheries lack the historical data necessary to assess their current status or set sustainable catch limits. Marine reserves may provide reference areas that help us evaluate the impact of fishing in nearby areas. However, monitoring marine reserves is generally more costly than collecting information from fishery landings. Using a simulation technique called management strategy evaluation, Sarah is examining the tradeoffs between the cost of data collection, the risk to fish populations, and fishery yields when reserve-based assessment methods are implemented. The results of this comparison will be used to inform assessments of nearshore rockfish stocks along the central California coast.

Sarah’s other research interests involve sustainable seafood initiatives. Sarah, along with other graduate students at UCSB, convened a group of experts for a workshop to assess the sustainability of fish stock certified by the Marine Stewardship Council. She is currently involved in a project to develop and evaluate the performance of data-poor stock assessment methods that can be used to certify community-based fisheries in the developing world, many of which lack the management infrastructure needed to qualify for certification under the current standards.

Dissertation Abstract
Marine Protected Areas (MPA) can benefit fisheries, but also present a number of challenges for traditional fisheries management approaches. By restricting fishing, MPAs allow fish populations in protected areas to return to unfished conditions. This increases the spatial heterogeneity in fish stocks, presenting a difficulty for traditional stock assessment techniques. However, this may also provide a source of new information for data-poor stocks. This forms the theoretical basis for the recent development of assessment techniques that utilize data from inside marine reserves to assess fished populations outside of reserves. In this dissertation I compare the performance of a suite of MPA-based data-poor methods, both in the short and long term under a range of different kinds of uncertainty. The results indicate that all assessment methods are sensitive to the time since MPA creation, historical fishing pressure, and movement, but that the methods that rely on length data are more robust to these conditions than those that rely on CPUE data. When paired with a control rule, all of the assessment methods performed reasonably well, suggesting that MPA-based assessment techniques may provide a viable option for the management of sedentary data-poor stocks.

Office: Bren Hall 1306


Gutiérrez, NL, Valencia, SR, Branch, TA, Agnew, DJ, Baum, JK, Bianchi, PL, Cornejo- Donoso, J, Costello, C, Defeo, O, Essington, TE, Hilborn, R, Hoggarth, DD, Larsen, AE, Ninnes, C, Sainsbury, K, Selden, Sistla, S, RL, Smith, ADM, Stern-Pirlot, A, Teck, SJ, Thorson, JT, Williams, NE. 2012. Eco-label conveys reliable information on fish stock health to seafood consumers. PLoS ONE 7(8): e43765. doi:10.1371/journal.pone.0043765

Work in Progress

Valencia, SR and Kay, M. The missing link: Assessing the ability of the seafood supply chain to transmit demand for sustainable seafood. In prep for Marine Policy.

Valencia, SR, White, C, and Kendall, BE. Optimal Harvest Strategies for a Rebuilding Population. In prep for Ecological Applications.

Valencia, SR, Prince, JD. Derivation of a size-based Spawning Potential Ratio estimator for use in management of data-poor stocks. In prep for International Council for the Exploration of the Sea.

Valencia, SR, Lenihan, HS. What is the value information from marine reserves? In Prep for Fish and Fisheries. 

Collaborative Projects

California Collaborative Fisheries Research Program

Developing A Fisheries Management Plan for California Spiny Lobster

Developing Cooperative Fisheries Management in California


  • National Science Foundation Graduate Research Fellowship, 2009-2012
  • UCSB Graduate Student Division Doctoral Scholars Fellowship, 2008-2013
  • Henry Luce Foundation Environmental Science to Solutions Fellowship, 2010-2012
  • Switzer Environmental Fellowship Finalist, 2011