[MARMAM] New paper on UK harbour porpoise densities

Kimberly Nielsen knielsen at sandiego.edu
Tue Oct 5 06:24:57 PDT 2021

My co-authors and I are pleased to share the publication of our new paper
on harbour porpoise distribution and abundance along ferry routes in the

Nielsen KA, Robbins JR, Embling CB (2021) Spatio-temporal patterns in
harbour porpoise density: citizen science and conservation in UK seas. Mar
Ecol Prog Ser 675:165-180. https://doi.org/10.3354/meps13828

ABSTRACT: Fisheries-induced mortality poses a threat to the conservation of
small cetaceans, particularly those found in productive coastal waters.
Harbour porpoises *Phocoena phocoena* are ubiquitous in UK seas, but
despite their prevalence, knowledge gaps remain on fine-scale space use. A
deeper understanding of how distributions vary in space and time is
required for appropriate management. Citizen science programs which collect
standardized data aboard platforms of opportunity can help uncover patterns
and identify higher density areas in the time between surveys of absolute
abundance. Here, we analyze citizen science data collected from ferries to
investigate spatio-temporal patterns in porpoise densities along routes in
UK waters. Region-specific detection functions and generalized additive
models were used to estimate abundance and elucidate relationships between
distributions and environmental variables. The highest densities during the
study period (2006-2017) were found southwest of Cornwall, followed by the
North Sea and the English Channel. Average density in the North Sea
increased substantially during this time, suggesting new high-use areas
along these routes. Density surface models showed strong relationships with
coastal waters, sea surface temperature, chlorophyll, and water column
dynamics. Contrasting preferences for stratified waters in the North Sea
and well-mixed areas in the channel suggest distinct foraging behaviours.
Higher density areas were identified in the southwestern and northeastern
UK, indicating priority areas for conservation efforts, especially in
Cornish waters where porpoises are highly vulnerable to bycatch. Findings
highlight how citizen science, together with robust density estimation, can
contribute to the conservation management of a common, although threatened,

Please contact me for more information.

Kimberly Nielsen
knielsen at sandiego.edu
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