The U.S. Navy has a pressing need for reliable estimates of density for many marine species, and how these densities vary in space and time. Such information is central to estimates of “takes” arising from testing and training activities, and for long-term population monitoring; it can also be used when planning operations, where appropriate, to minimize expected impact.
Many approaches have been proposed and applied to density surface models used by the U.S. Navy (and more widely in the ecological research community).

Four key points are:

  1. different approaches can lead to very divergent estimates
  2. the relative merits of many methods are at present largely unclear
  3. many issues that make modelling these data complex remain unresolved
  4. there are several approaches that remain untested in this context. Given this, the reliability of current estimates is somewhat open to question.


We have created a working group of scientists involved in density surface modelling to coordinate advances on this topic. The group will be supported by dedicated post-doctoral staff, tasked with solving issues identified by the group.

Specific goals of the group are:

  1. Bring together scientific leaders in density surface modelling.
  2. Share information about best practices, without being prescriptive.
  3. Develop and implement innovative approaches for advancing spatial modelling methods to best characterize marine species seasonal abundance and distribution, focused on U.S. Navy training and testing areas.
  4. Provide user-friendly no-cost tools, where possible, implementing new approaches.
  5. Provide statistical support to those tasked with undertaking density surface modelling for the U.S. Navy.
  6. Provide accessible guidance for practitioners in the form of public reports or scientific publications.
  7. Highlight priority areas for continued research.
  8. Solicit input from the wider scientific community and share findings through public workshops.

The team

The project represents a collaboration between the University of St Andrews, Duke University and the regional NOAA Fisheries labs that are largely responsible for collection and analysis of line transect visual survey data used in U.S. Navy impact assessments.


University of St Andrews Len Thomas, Dave Miller, Catriona Harris, Phil Bouchet
Duke University Pat Halpin, Jason Roberts, Rob Schick, Ana Canadas
NOAA Samuel Chavez, Debi Palka, Doug Sigourney, Lance Garrison, Elizabeth Becker,
Karin Forney, Jeff Moore, Jessica Redfern, Paul Conn, Megan Ferguson,
Jay ver Hoef, Devin Johnson, Brett McClintock



This work is being funded by OPNAV N45 and the SURTASS LFA Settlement Agreement, and being managed by the U.S. Navy’s Living Marine Resources program under Contract No. N39430-17-C-1982.

For more information about the project, please contact the project manager Catriona Harris.