Species Distribution Models
Habitat-based density estimates for cetaceans in the California Current Ecosystem
SDM Overview
Cetacean species distribution models (SDMs) or “habitat models” estimate density as a continuous function of habitat variables (e.g., sea surface temperature, seafloor depth) and within the study area that was modeled, densities can be predicted at all locations where these habitat variables can be measured or estimated. SDMs therefore allow estimates of cetacean densities on finer spatial and temporal scales than traditional line-transect or mark-recapture analyses. CMAP develops SDMs for cetaceans using our extensive line-transect survey data, and predictions from these models provide valuable management tools for estimating the density and distribution of cetaceans and assessing potential impacts from a wide range of anthropogenic activities. SDMs for cetaceans have been developed for waters within the California Current Ecosystem (CCE) study area from systematic ship survey data collected by SWFSC since 1991 (relevant citations are included below).
The most recent CCE models provide spatially-explicit density predictions at a 0.1˚ (approximately 10km x 10km) grid resolution, and multi-year average density surfaces have been used by the US Navy, the Bureau of Ocean Energy Management (BOEM), and others to assess potential impacts on cetaceans as required by US regulations such as the Marine Mammal Protection Act and Endangered Species Act. Spatially-explicit density values for the CCE study area derived from model predictions on environmental conditions specific to the 1991–2014 line-transect survey data are available for download at the websites listed below. These “multi-year average” density surfaces are derived from model predictions made on separate environmental conditions for each day encompassing the CCE survey periods, thus taking into account the varying oceanographic conditions during the 1991–2014 cetacean surveys. The separate daily predictions provide a dataset from which averages can be derived for any temporal period of interest; yearly averages are available in csv format upon request from SWFSC.
Where you can access model outputs
Multi-year (1991-2014) average density surfaces can be downloaded from a range of sources. The following sites currently include models built with the SWFSC 1991-2014 survey data, but will eventually be updated to include recently developed models that also include data from the 2018 CCES survey.
NOAA’s Cetacean and Sound Mapping
This site provides information on cetacean data available for waters within the US Exclusive Economic Zone (EEZ) and is organized by regions at a monthly temporal resolution. The 1991–2014 average composites are shown as “hd” (habitat-based density) files by species within the West Coast (WC) region.
US Navy Marine Species Density Database for U.S. Pacific & Gulf of Alaska
This site includes a mapping tool for users to view and download marine species density surfaces used by the US Navy to assess potential impacts from their training and testing activities at study areas in waters of the Pacific and Gulf of Alaska. The site includes the 1991–2014 average composites for cetacean species within the CCE study area. The mapping tool displays the models in an online GIS that allows users to explore the outputs and generate density histograms for specific areas of interest.
Ocean Biodiversity Information System (OBIS) Spatial Ecological Analysis of Megavertebrate Populations (SEAMAP)
The OBIS-SEAMAP site is a spatially referenced online database that aggregates marine mammal, seabird, sea turtle and ray and shark observation data from across the globe. OBIS-SEAMAP provides a direct link to the PACGOA density mapper site described above under “Modeling Projects” on the front page.
Selected publications (listed from most recent)
Becker EA, Carretta JV, Forney KA, Barlow J, Brodie S, Hoopes R, Jacox MG, Maxwell SM, Redfern JV, Sisson NB, Welch H, Hazen EL. 2020. Performance Evaluation of Cetacean Species Distribution Models Developed Using Generalized Additive Models and Boosted Regression Trees. Ecology and Evolution 10, 5759-578.
Becker EA, Forney KA, Miller DL, Fielder PC, Barlow J, Moore JE. 2020. Habitat-Based Density Estimates for Cetaceans in the California Current Ecosystem Based on 1991-2018 Survey Data. NOAA Technical Memorandum NMFS-SWFSC-638.
Redfern JV, Becker EA, Moore TJ. 2020. Effects of Variability in Ship Traffic and Whale Distributions on the Risk of Ships Striking Whales. Frontiers in Marine Science 6:793.
Redfern JV, Moore TJ, Becker EA, Calambokidis J, Hastings SP, Irvine LM, Mate BR, Palacios DM. 2019. Evaluating Stakeholder‐Derived Strategies to Reduce the Risk of Ships Striking Whales. Diversity and Distributions 25, 1575–1585.
Becker EA, Forney KA, Redfern JV, Barlow J, Jacox MG, Roberts JJ, Palacios DM. 2018. Predicting Cetacean Abundance and Distribution in a Changing Climate. Diversity and Distributions 25(4):626-643.
Boyd C, Barlow J, Becker EA, et al. 2018. Estimation of Population Size and Trends for Highly Mobile Species with Dynamic Spatial Distributions. Diversity and Distributions 24: 1-12.
Becker EA, Forney KA, Thayre BJ, Debich AJ, Campbell GS, Whitaker K, Douglas AB, Gilles A, Hoopes R, Hildebrand JA. 2017. Habitat-Based Density Models for Three Cetacean Species Off Southern California Illustrate Pronounced Seasonal Differences. Frontiers in Marine Science 4(121):1–14.
Becker EA, Forney KA, Fiedler PC, Barlow J, Chivers SJ, Edwards CA, Moore AM, Redfern JV. 2016. Moving Towards Dynamic Ocean Management: How Well Do Modeled Ocean Products Predict Species Distributions? Remote Sensing 8(2):149.
Becker EA, Forney KA, Foley DG, Smith RC, Moore TJ, Barlow J. 2014. Predicting Seasonal Density Patterns of California Cetaceans Based On Habitat Models. Endangered Species Research 23, 1–22.
Redfern JV, McKenna MF, Moore TJ, Calambokidis J, Deangelis ML, Becker EA, Barlow J, Forney KA, Chivers SJ. 2013. Assessing the Risk of Ships Striking Large Whales in Marine Spatial Planning. Conservation Biology 27: 292-302.
Becker EA, Foley DG, Forney KA, Barlow J, Redfern JV, Gentemann CL. 2012. Forecasting Cetacean Abundance Patterns to Enhance Management Decisions. Endangered Species Research 16, 97–112.
Becker EA, Forney KA, Ferguson MC, Barlow J, Redfern JV. 2012. Predictive Modeling of Cetacean Densities in the California Current Ecosystem Based on Summer/Fall Ship Surveys in 1991-2008. U.S. Department of Commerce, NOAA Technical Memorandum NMFS-SWFSC-499.
Forney KA, Ferguson MC, Becker EA, Fiedler PC, Redfern JV, Barlow J, Vilchis IL, Ballance LT. 2012. Habitat-Based Spatial Models of Cetacean Density in the Eastern Pacific Ocean. Endangered Species Research 16:113-133.
Becker EA, Forney KA, Ferguson MC, Foley DG, Smith RC, Barlow J, Redfern JV. 2010. Comparing California Current Cetacean–Habitat Models Developed Using In Situ and Remotely Sensed Sea Surface Temperature Data. Marine Ecology Progress Series 413:163–183.
Barlow J, Ferguson MC, Becker EA, Redfern JV, Forney KA, Vilchis IL, Fiedler PC, Gerrodette T, Ballance LT. 2009. Predictive Modeling of Cetacean Densities in the Eastern Pacific Ocean. NOAA Technical Memorandum NMFS-SWFSC-444.
Forney KA. 2000. Environmental Models of Cetacean Abundance: Reducing Uncertainty in Population Trends. Conservation Biology 14(5), 1271-1286.