Influence of environmental variability on harbour porpoise movement

TY - JOUR

T1 - Influence of environmental variability on harbour porpoise movement

AU - Stalder, Dominique

AU - van Beest, Floris

AU - Sveegaard, Signe

AU - Dietz, Rune

AU - Teilmann, Jonas

AU - Nabe-Nielsen, Jacob

PY - 2020/8

Y1 - 2020/8

N2 - The harbour porpoise Phocoena phocoena is a small marine predator with a high conservation status in Europe and the USA. To protect the species effectively, it is crucial to understand its movement patterns and how the distribution of intensively used foraging areas can be predicted from environmental conditions. Here, we investigated the influence of both static and dynamic environmental conditions on large-scale harbour porpoise movements in the North Sea. We used long-term movement data from 57 individuals tracked during 1999-2017 in a state-space model to estimate the underlying behavioural states, i.e. whether animals used area-restricted or directed movements. Subsequently, we assessed whether the probability of using area-restricted movements was related to environmental conditions using a generalized linear mixed model. Harbour porpoises were more likely to use area-restricted movements in areas with low salinity levels, relatively high chlorophyll a concentrations and low current velocity, and in areas with steep bottom slopes, suggesting that such areas are important foraging grounds for porpoises. Our study identifies environmental parameters of relevance for predicting harbour porpoise foraging hot spots over space and time in a dynamic system. The study illustrates how movement patterns and data on environmental conditions can be combined, which is valuable to the conservation of marine mammals.

AB - The harbour porpoise Phocoena phocoena is a small marine predator with a high conservation status in Europe and the USA. To protect the species effectively, it is crucial to understand its movement patterns and how the distribution of intensively used foraging areas can be predicted from environmental conditions. Here, we investigated the influence of both static and dynamic environmental conditions on large-scale harbour porpoise movements in the North Sea. We used long-term movement data from 57 individuals tracked during 1999-2017 in a state-space model to estimate the underlying behavioural states, i.e. whether animals used area-restricted or directed movements. Subsequently, we assessed whether the probability of using area-restricted movements was related to environmental conditions using a generalized linear mixed model. Harbour porpoises were more likely to use area-restricted movements in areas with low salinity levels, relatively high chlorophyll a concentrations and low current velocity, and in areas with steep bottom slopes, suggesting that such areas are important foraging grounds for porpoises. Our study identifies environmental parameters of relevance for predicting harbour porpoise foraging hot spots over space and time in a dynamic system. The study illustrates how movement patterns and data on environmental conditions can be combined, which is valuable to the conservation of marine mammals.

KW - Argos satellite tracking

KW - North sea

KW - Phocoena phocoena

KW - arearestricted search

KW - cetacean concervation

KW - harbor porpoise

KW - movement behavior

KW - switching state-space model

UR - http://www.scopus.com/inward/record.url?scp=85091136873&partnerID=8YFLogxK

U2 - 10.3354/meps13412

DO - 10.3354/meps13412

M3 - Journal article

SN - 0171-8630

VL - 648

SP - 207

EP - 219

JO - Marine Ecology Progress Series

JF - Marine Ecology Progress Series

ER -