Suspected white shark (Carcharodon carcharias) predation on an adult Atlantic sturgeon (Acipenser oxyrinchus) from the Gulf of Maine

Abstract Atlantic sturgeon ( Acipenser oxyrinchus ) are threatened under the United States Endangered Species Act in the Gulf of Maine (GoM), where natural sources of adult mortality remain poorly documented. We report a stranded adult female Atlantic Sturgeon (224-cm total length) recovered in Scarborough, Maine, USA, with injury consistent with predation by a juvenile white shark ( Carcharodon carcharias ) and inconsistent with vessel strike. Bite-mark analysis indicated a shark of at least 2.6 m total length, matching juveniles increasingly documented in nearby Saco Bay. The stranding coincided with peak seasonal white shark activity within known sturgeon foraging area, supporting predation as the most parsimonious cause of death. Predation on adult Atlantic sturgeon has only been known via tooth-mark injuries on surviving individuals in Canadian weir fisheries making this the first direct evidence of the interaction in the GoM. As white sharks expand into warming GoM waters, such encounters may become more frequent, highlighting the need for continued monitoring of shifting predator-prey dynamics.