Skip to content

Research at St Andrews

From here and now to there and then: practical recommendations for extrapolating cetacean density surface models to novel conditions

Research output: Book/ReportOther report

Abstract

Density surface models (DSMs) are clearly established as a method of choice for the analysis of cetacean line transect survey data, and are increasingly used to inform risk assessments in remote marine areas subject to rising anthropogenic impacts (e.g. the high seas). However, despite persistent skepticism about the validity of extrapolated models, more and more DSMs are being applied well beyond the boundaries of the study regions where field sampling originally took place. This leads to potentially uncertain and error-prone model predictions that may mislead on-the-ground management interventions and undermine conservation decision-making. In addition, no consensus currently exists on the best way to define and measure extrapolation when it occurs, leaving users without the tools they require to audit models projected into novel conditions. Consequently, a transparent and consistent protocol for identifying scenarios under which extrapolation may be appropriate (or conversely, ill-advised) is urgently needed to better gauge how models behave outside the boundaries of sample data and to know how much faith can be placed in their outputs.

This report aims to address this gap by synthesising recent advances in extrapolation detection, and presenting recommendations for a minimum standard for measuring extrapolation in novel environmental space. Such guidelines are essential to promoting transparency, replicability, and quality control, and will help marine scientists, managers and policy agencies to (i) better interpret density surfaces and their associated uncertainty; (ii) refine model development and selection approaches; and (iii) optimise the allocation of future survey effort by identifying priority knowledge gaps, e.g. by delineating areas where model predictions are the least supported by data. Our review is accompanied by supplementary R code offering a user-friendly framework for quantifying, summarising and visualising various forms of extrapolation in multivariate environmental space a priori (ahead of model fitting). We illustrate its application with case studies designed to revisit previously published predictions of sperm whale (Physeter macrocephalus) and beaked whale (Ziphiidae spp.) densities in the Northwest Atlantic, and evaluate them in light of several extrapolation metrics.

Very early in their training, ecologists are given strong warnings against extrapolating, as model predictions made in data-deficient contexts rely heavily on assumptions that may not hold outside the range of sampled conditions. Navigating the ‘uncharted waters’ of extrapolation, however, is critical to scientific progress, and will be best achieved with a clear understanding of the mechanics, benefits, and limitations of extrapolated models.
Close

Details

Original languageEnglish
PublisherUniversity of St Andrews
Commissioning bodyLiving Marine Resources
Number of pages59
Publication statusPublished - 4 Sep 2019

Publication series

NameCREEM Technical Report
No.2019-1

Discover related content
Find related publications, people, projects and more using interactive charts.

View graph of relations

Related by author

  1. Distance sampling in R

    Miller, D. L., Rexstad, E., Thomas, L., Marshall, L. & Laake, J. L., 9 May 2019, In : Journal of Statistical Software. 89, 1, 28 p.

    Research output: Contribution to journalArticle

  2. Marine mammals and sonar: dose-response studies, the risk-disturbance hypothesis and the role of exposure context

    Harris, C. M., Thomas, L., Falcone, E., Hildebrand, J., Houser, D., Kvadsheim, P., Lam, F-P. A., Miller, P., Moretti, D. J., Read, A., Slabbekoorn, H., Southall, B. L., Tyack, P. L., Wartzok, D. & Janik, V. M., Jan 2018, In : Journal of Applied Ecology. 55, 1, p. 396-404

    Research output: Contribution to journalReview article

  3. Individual, ecological, and anthropogenic influences on activity budgets of long-finned pilot whales

    Isojunno, S., Sadykova, D., DeRuiter, S., Curé, C., Visser, F., Thomas, L., Miller, P. J. O. & Harris, C. M., Dec 2017, In : Ecosphere. 8, 12, 26 p., e02044.

    Research output: Contribution to journalArticle

  4. From physiology to policy: a review of physiological noise effects on marine fauna with implications for mitigation

    Aguilar De Soto, N., Gkikopoulou, K., Hooker, S., Isojunno, S., Johnson, M., Miller, P., Tyack, P., Wensveen, P., Donovan, C., Harris, C. M., Harris, D., Marshall, L., Oedekoven, C., Prieto, R. & Thomas, L., Dec 2016, In : Proceedings of Meetings on Acoustics. 27, 1, 14 p., 040008.

    Research output: Contribution to journalReview article

  5. The challenges of analyzing behavioral response study data: an overview of the MOCHA (Multi-study OCean acoustics Human effects Analysis) project

    Harris, C. M., Thomas, L., Sadykova, D., De Ruiter, S. L., Tyack, P. L., Southall, B. L., Read, A. J. & Miller, P., 2016, Effects of Noise on Aquatic Life II. Popper, A. N. & Hawkins, A. (eds.). Springer Science and Business Media, p. 399-407 9 p. (Advances in Experimental Medicine and Biology; vol. 875).

    Research output: Chapter in Book/Report/Conference proceedingConference contribution

ID: 261009868

Top