## Questions Frequently Asked by Marine Mammal Density Surface Modelers ## In 2018, the [U.S. Navy Living Marine Resources (LMR)][1] program initiated the "DenMod" collaboration between us--the [Centre for Research into Ecological and Environmental Modelling (CREEM)][2] at the University of St. Andrews, the [Marine Geospatial Ecology Laboratory][3] at Duke University, and the [NOAA Fisheries Science Centers][4]--to develop best practices for density surface modeling of marine species and provide practical guidance to the modeling community, particularly those involved in modeling marine mammals for the Navy's training and testing areas. Pursuant to this goal, we developed this collection of answers to technical modeling questions frequently asked by ourselves and external colleagues. Through this corpus, we offer ready solutions to common modeling problems, distilled from our experiences developing [distance sampling][5] and [density surface modeling][6] methodology, and applying it in the development of marine mammal density models for the Navy. How the questions are organized ------------------------------- The questions are organized into wiki pages, with one or more related questions occurring in sequence on each page. The pages are grouped into several "components". You can drill into the navigation hierarchy on the left or click the component links below: - [DSM Workflows][7] - [Surveys and Survey Data][8] - [Detection Models][9] - [Spatial Models][10] Scope of the questions ---------------------- Most of the practitioners within our collaboration have focused on modeling the absolute abundance (number of individuals) and density (individuals per unit area) of marine mammals, usually over large expanses (100s-1000s km) of marine waters of the United States, typically by applying methods derived from distance sampling to visual line transect surveys conducted from ships and aircraft. The questions that appear here reflect this focus. ![Focus of our questions][11] Our questions are scoped to the modeling procedures used to build density and uncertainty surfaces (i.e. maps) from data that have already been collected. However, data should be collected with an intended analysis in mind, and survey plans and observation protocols designed accordingly. For guidance, we suggest [Buckland et al. (2001)][12] as a starting point. Finally, while many of our own modeling projects have been utilized by the U.S. Navy to model the effects of its training and testing activities on marine animal populations, often to produce "take estimates" or other formal results for permits under U.S. law, the details of the Navy's own modeling activities are mostly beyond the scope of the questions we address here. ![Focus of our questions][13] How to cite this FAQ -------------------- To obtain a citation, go to the [main project page][14] and click the Citation dropdown. Contact us ---------- To ask a question or suggest material for this FAQ, please contact [Jason Roberts](mailto:jason.roberts@duke.edu). [1]: http://navysustainability.dodlive.mil/environment/lmr/ [2]: https://www.creem.st-andrews.ac.uk/ [3]: https://mgel.env.duke.edu/ [4]: https://www.fisheries.noaa.gov/contact-directory/science-centers [5]: https://doi.org/10.1111/j.1365-2664.2009.01737.x [6]: https://doi.org/10.1111/2041-210X.12105 [7]: https://osf.io/xsfdy/wiki [8]: https://osf.io/rm86p/wiki [9]: https://osf.io/yp27g/wiki [10]: https://osf.io/wgc4f/wiki [11]: https://files.osf.io/v1/resources/5eza8/providers/osfstorage/5c65bf58f9de85001a2f08bb?mode=render [12]: https://global.oup.com/academic/product/introduction-to-distance-sampling-9780198509271 [13]: https://files.osf.io/v1/resources/5eza8/providers/osfstorage/5c65c15716506900170d7425?mode=render [14]: https://osf.io/5eza8/