Dear MARMAM community,
My co-authors and I would like to share our latest publication in the journal
of Aquatic Conservation: Marine and Freshwater Ecosystems:
Tiffany Goh, Enrico Pirotta, Oriol Giralt Paradell, Mark Jessopp, Emer Rogan.
2026. Mapping seasonal interaction risk between harbour porpoises and gillnet
fisheries to inform management thresholds. Aquatic Conservation: Marine and
Freshwater Ecosystems 36, no. 7: e70415.
Abstract:
When empirical bycatch data are limited, risk-based assessments offer a
valuable tool for identifying areas where marine mammals and fisheries are most
likely to interact. The harbour porpoise (Phocoena phocoena) is among the most
vulnerable to incidental capture in gillnet fisheries. Although protected under
European legislation, monitoring and mitigation efforts in Ireland remain
insufficient to fully assess and address bycatch. Recent harbour porpoise
abundance estimates indicate a declining trend in Irish waters, with bycatch
considered a potential contributing factor. Here, we assessed seasonal spatial
patterns of harbour porpoise–gillnet interaction risk by combining predicted
porpoise distribution with gillnet fishing effort data for summer and winter
between 2015 and 2022. Allowable bycatch thresholds, representing the maximum
number of individuals that can be removed without causing population decline,
were calculated using 2022 abundance estimates and a range of recovery factors
and intrinsic growth rates for porpoises within the Irish Exclusive Economic
Zone. Areas of elevated bycatch risk were consistently identified in the Celtic
Sea and along the continental shelf off Ireland's west coast, indicating
persistent zones of potential exposure. Calculated bycatch thresholds were low
across all parameterisations, suggesting limited tolerance for additional
mortality in a declining population. Although empirical bycatch data are
required to determine the bycatch rate, these findings highlight priority areas
for monitoring and mitigation. Overall, this study provides a spatially
explicit framework to inform precautionary management of harbour
porpoise–gillnet interactions in Irish waters.
The PDF copy can be downloaded at: https://doi.org/10.1002/aqc.70415
Have a lovely weekend,
Tiff
Dr Tiffany Goh
Postdoctoral Researcher
ObSERVE III aerial survey programme
University College Cork
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