TY - JOUR

T1 - Spatiotemporal mortality and demographic trends in a small cetacean

T2 - Strandings to inform conservation management

AU - IJsseldijk, Lonneke L.

AU - ten Doeschate, Mariel T.

AU - Brownlow, Andrew

AU - Davison, Nicholas J.

AU - Deaville, Rob

AU - Galatius, Anders

AU - Gilles, Anita

AU - Haelters, Jan

AU - Jepson, Paul D.

AU - Keijl, Guido O.

AU - Kinze, Carl Chr

AU - Olsen, Morten Tange

AU - Siebert, Ursula

AU - Thostesen, Charlotte Bie

AU - van den Broek, Jan

AU - Grone, Andrea

AU - Heesterbeek, Hans

PY - 2020

Y1 - 2020

N2 - With global increases in anthropogenic pressures on wildlife populations comes a responsibility to manage them effectively. The assessment of marine ecosystem health is challenging and often relies on monitoring indicator species, such as cetaceans. Most cetaceans are however highly mobile and spend the majority of their time hidden from direct view, resulting in uncertainty on even the most basic population metrics. Here, we discuss the value of long-term and internationally combined stranding records as a valuable source of information on the demographic and mortality trends of the harbour porpoise (Phocoena phocoena) in the North Sea. We analysed stranding records (n = 16,181) from 1990 to 2017 and demonstrate a strong heterogeneous seasonal pattern of strandings throughout the North Sea, indicative of season-specific distribution or habitat use, and season-specific mortality. The annual incidence of strandings has increased since 1990, with a notable steeper rise particularly in the southern North Sea since 2005. A high density of neonatal strandings occurred specifically in the eastern North Sea, indicative of areas important for calving, and large numbers of juvenile males stranded in the southern parts, indicative of a population sink or reflecting higher male dispersion. These findings highlight the power of stranding records to detect potentially vulnerable population groups in time and space. This knowledge is vital for managers and can guide, for example, conservation measures such as the establishment of time-area -specific limits to potentially harmful human activities, aiming to reduce the number and intensity of human -wildlife conflicts.

AB - With global increases in anthropogenic pressures on wildlife populations comes a responsibility to manage them effectively. The assessment of marine ecosystem health is challenging and often relies on monitoring indicator species, such as cetaceans. Most cetaceans are however highly mobile and spend the majority of their time hidden from direct view, resulting in uncertainty on even the most basic population metrics. Here, we discuss the value of long-term and internationally combined stranding records as a valuable source of information on the demographic and mortality trends of the harbour porpoise (Phocoena phocoena) in the North Sea. We analysed stranding records (n = 16,181) from 1990 to 2017 and demonstrate a strong heterogeneous seasonal pattern of strandings throughout the North Sea, indicative of season-specific distribution or habitat use, and season-specific mortality. The annual incidence of strandings has increased since 1990, with a notable steeper rise particularly in the southern North Sea since 2005. A high density of neonatal strandings occurred specifically in the eastern North Sea, indicative of areas important for calving, and large numbers of juvenile males stranded in the southern parts, indicative of a population sink or reflecting higher male dispersion. These findings highlight the power of stranding records to detect potentially vulnerable population groups in time and space. This knowledge is vital for managers and can guide, for example, conservation measures such as the establishment of time-area -specific limits to potentially harmful human activities, aiming to reduce the number and intensity of human -wildlife conflicts.

KW - Surveillance programme

KW - Wildlife monitoring

KW - Marine mammal

KW - Mortality

KW - North Sea

KW - Harbour porpoise

KW - Phocoena phocoena

KW - CITIZEN SCIENCE DATA

KW - HARBOR PORPOISES

KW - NORTH-SEA

KW - PHOCOENA-PHOCOENA

KW - AERIAL SURVEYS

KW - ABUNDANCE

KW - INSIGHTS

KW - MODELS

KW - RECORD

KW - WATERS

U2 - 10.1016/j.biocon.2020.108733

DO - 10.1016/j.biocon.2020.108733

M3 - Journal article

VL - 249

JO - Biological Conservation

JF - Biological Conservation

SN - 0006-3207

M1 - 108733

ER -