Prevalence of imbedded and ingested shot gun pellets in breeding sea ducks in the Baltic Sea—possible implications for future conservation efforts

Abstract

Several sea duck species in Europe face dwindling population numbers with following increased conservation focus. Shot gun practices may put extra pressure on populations not only by direct hunting mortality but also crippling and lead poisoning from ingestion of pellets. In this study, we examined three sea duck species breeding in the Swedish Archipelago of the Baltic Sea by x-raying trapped incubating females to detect prevalence of imbedded and ingested shot gun pellets. The study was carried out during the 2021 and 2022 breeding seasons and designed to aid our understanding of the role of physical restraints of putative pellets to breeding performance at our study site. A total of 205 individual females of common eider (n = 113), velvet scoter (n = 57), and red-breasted merganser (n = 35) were x-rayed without finding any imbedded or ingested pellets. For this study, a combination of decreasing hunting pressure, remoteness of study site, improved hunters’ shooting performance along the flyway and depletion of crippling rates due to life-long negative effects of carrying imbedded pellets may explain our finding on non-detection. For common eider, specific interventions to reduce the negative impacts of shotgun practices have been reported successful, and our data suggest a continuing positive trend. Based on our findings, we advise future conservation efforts for the three species, breeding in this part of the flyway, to focus on other factors that may have negative impact on incubating female survival and reproduction.