Harbor Porpoises ( <scp> <i>Phocoena phocoena</i> </scp> ) in Dublin Bay: How Does Dredge Disposal Affect Foraging Behavior?

ABSTRACT Harbor porpoises ( Phocoena phocoena ) are among the most widespread cetacean species in Irish waters and are listed under Annex II of the EU Habitats Directive as a species of community importance. The local harbor porpoise population in Dublin Bay coexists with designated spoil grounds for dredging activity, which has increased due to Dublin Port's Alexandra Basin Redevelopment (ABR) project. This study examines the long‐ and short‐term effects of dredge disposal on harbor porpoise foraging behavior over a 5‐year period (2017–2021). Acoustic monitoring using C‐PODs was conducted inside and outside the Burford Bank disposal site. The effect of dredge disposal on foraging intensity (quantified by hourly buzz:click ratio) was analyzed using Generalized Additive Mixed Models (GAMMs) and assessed using modified Before–After (BA) and Before–After Control‐Impact (BACI) frameworks. We classified 33% of detected clicks as buzzes. Foraging intensity increased during three of the four dredging phases compared to non‐dredging periods at all monitored locations, including the control site. Short‐term responses, however, were highly site‐specific. These findings suggest that dredge disposal had no obvious negative impact on harbor porpoise foraging behavior and may have increased food availability. This study provides valuable insights into balancing species conservation with infrastructure development.