*Workshop announcement - Advancing Marine Species Density Surface Modelling* *Open workshop, Sunday 22 October 2017 (prior to Society for Marine Mammalogy Conference), Halifax, Nova Scotia* Density surface models (sometimes called spatial or habitat models) attempt to describe animal distribution as a function of spatially referenced variables. Data typically come from line transect surveys, although there is the potential to use other effort-indexed surveys, such as passive acoustics. Outputs include modelled relationships between density and explanatory variables, spatial maps of population density, and estimates of population size with uncertainty in areas of interest within the larger modelled region. Outputs are of practical use in, for example, marine spatial planning and impact assessment. There are many statistical methods available for density surface modeling. This one-day workshop is part of the start-up meeting of a research project, DenMod, that aims to compare the different approaches, identify outstanding issues and address some of them. The project is a collaboration between the University of St Andrews, Duke University and the regional NOAA Fisheries labs, and is funded by the US Navy. The goal of the workshop is to solicit input on the project goals and plans from developers and users of density surface models and their outputs. We will briefly present the methods we are considering, and invite comments. We also invite participants to present their research relating to density surface modeling. The workshop will be of interest to researchers who create density surface models as well as those who use the outputs. The workshop is free but due to venue size, places are limited. If you are interested in attending, please register by emailing Catriona Harris (catriona.harris@st-andrews.ac.uk <mailto:catriona.harris@st-andrews.ac.uk>). If you would like to be considered for a presentation slot then please include a short abstract (no longer than 100 words) when you register.