Article Concludes Whalewatching Doesn’t Cause Long-Term Negative Effects on Minke Whales

The following article is being published in the Journal of Wildlife Management: Christiansen, F., Bertulli, C.G., Rasmussen, M. & Lusseau, D. 2015. Estimating Cumulative Exposure of Wildlife to Non-Lethal Disturbance Using Spatially Explicit Capture-Recapture Models. The Journal of Wildlife Management. DOI: 10.1002/jwmg.836. The article’s abstract reads as follows:

“Impact assessments often focus on short-term behavioral responses of animals to human disturbance. However, it is the cumulative effects caused by repeated behavioral disruptions which are of management concern, since these effects have the potential to influence individuals? survival and reproduction. We need to estimate individual exposure rates to disturbance in order to determine cumulative effects. In this study we present a new approach to estimate the spatial exposure of minke whales to whalewatching boats in Faxafli bay, Iceland. We use recent advances in spatially explicit capture recapture modelling to estimate the probability that whales will encounter a disturbance (i.e. whalewatching boat). Spatially-explicit individual encounter histories of individually-identifiable animals were obtained using photo-identification. The study area was divided into 1 km2 grid cells, where each cell was considered a spatially distinct sampling unit. We used capture history of individuals to model and estimate spatial encounter probabilities of individual minke whales across the study area, accounting for heterogeneity in sampling effort. We inferred the exposure of individual minke whales to whalewatching vessels throughout the feeding season by estimating individual whale encounters with vessels using the whale encounter probabilities and spatially-explicit whalewatching intensity in the same area, obtained from recorded whalewatching vessel tracks. We could then estimate the cumulative time whales spent with whalewatching boats to assess the biological significance of whalewatching disturbances. The estimated exposure levels to boats varied considerably between individuals, due to both temporal and spatial variations in the activity centers of whales and the whalewatching intensity in the area. However, although some whales were repeatedly exposed to whalewatching boats throughout the feeding season, the estimated cumulative time they spent with boats was very low. While whalewatching boat interactions caused feeding disruptions for the whales, the estimated low cumulative exposure makes it unlikely that the whalewatching industry in its current state is having any long-term negative effects on vital rates.”

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