Western Atlantic Torpedo Strandings on Cape Cod in the Fall and Early Winter of 2020 and 2021, Including Mass Stranding Events on Long Point, Provincetown, MA.

Carson, Carol D. “Krill”¹, Jack N. Gerrior², John Chisholm³, ¹New England Coastal Wildlife Alliance, Middleboro, MA, ²Massachusetts Maritime Academy, Bourne, MA, ³Anderson Cabot Center for Ocean Life, Boston, MA

The batoid species Tetronarce occidentalis (Western Atlantic Torpedo) inhabits the coastal waters of the Gulf of Maine, though little is understood regarding its movements, and life history. Since 2011, the New England Coastal Wildlife Alliance (NECWA) has informally documented Torpedo strandings each fall and early winter in the New England area. In 2020 and 2021, NECWA conducted formal investigations and documented a total of 90 rays with all individuals stranding dead except for 1 individual in both 2020 and 2021. In 2020, 63 carcasses (34 Female, 15 Male, 14 CBD) stranded and in 2021, 27 carcasses (12 Female, 8 Male, 7 CBD) stranded. Documentation included positional information, photo-ID images, sex determination, and weight. For all specimens except those that were heavily scavenged or decomposed, body measurements were collected, including total length (TL), disk width (DW), disk length (DL) and tail length (CL). The digestive tracts of 50 carcasses were examined and 12 contained various species of decomposed fish, except for 1 large female that had a whole long-tailed duck (Clangula hyemalis) in her stomach. In both years, a hot spot for strandings was identified on Long Point, Provincetown, MA. Historical records indicate the occurrence of large numbers of Torpedos in the vicinity of Provincetown, including those that stranded on the eastern shore of Long Point. Annual strandings of Torpedos on Cape Cod remind us how little is known regarding the biology and ecology of this species and encourages further investigation into the causes of both singular and mass stranding events.