[MARMAM] New publication on estimating exposure to boat traffic with spatially explicit capture–recapture models

Enrico Pirotta pirotts at libero.it
Wed Apr 30 03:52:30 PDT 2014

Dear MARMAM colleagues,

We are pleased to announce that the following paper has been made available 

Enrico Pirotta, Paul M. Thompson, Barbara Cheney, Carl Donovan, David Lusseau 
(In press). Estimating spatial, temporal and individual variability in dolphin 
cumulative exposure to boat traffic using spatially explicit capture–recapture 
methods. Animal Conservation. DOI: 10.1111/acv.12132

Appropriate management of the effects of human activities on animal 
populations requires quantification of the rate at which animals encounter 
stressors. Such activities are heterogeneously distributed in space, as are the 
individual animals in a population. This will result in a heterogeneous 
exposure rate, which is also likely to vary over time. A spatially explicit 
analysis of individual exposure is therefore required. We applied Bayesian 
spatially explicit capture–recapture models to photo-identification data to 
estimate the home range of well-marked individuals in a protected coastal 
population of bottlenose dolphins. Model results were combined with the 
estimated distribution of boat traffic to quantify how exposure to this 
disturbance varied in time and space. Variability in exposure between 
individuals was also investigated using a mixed-effects model. The cumulative 
individual exposure to boat traffic varied between summers, depending both on 
the overall area usage and the degree of individual movement around the 
activity centres. Despite this variability, regions of higher risk could be 
identified. There were marked inter-individual differences in the predicted 
amount of time dolphins spent in the presence of boats, and individuals tended 
to be consistently over- or underexposed across summers. Our study offers a 
framework to describe the temporal, spatial and individual variation in 
exposure to anthropogenic stressors when individuals can be repeatedly 
identified over time. It provides opportunities to map exposure risk and 
understand how this evolves in time at both individual and population levels. 
The outcome of such modelling can be used as a robust evidence base to support 
management decisions.

KEY WORDS: Bayesian modelling; capture–recapture; disturbance; dolphin; 
exposure rate; home range; marine traffic; Tursiops truncatus.

A PDF copy of the work can be downloaded from: 

Please do not hesitate to contact me for any question regarding our work.

All the best,
Enrico Pirotta

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