The North Atlantic right whale (Eubalaena glacialis), one of the most endangered species of large whales, has only 411 individuals remaining in the population.1 Their survival is overtly threatened by two sources of anthropogenic trauma: entanglement in fishing gear and collisions with ships.2,3,4,5 Seventy mortalities of E. glacialis occurred between 2003 and 2018 (1 Dec) from Florida, U.S.A. to the Gulf of St. Lawrence, Canada: 28 adults, 15 juveniles, 10 calves, and 17 unknown age class. Females represented 66.7% (18/27) of known-sex adult cases. Fifty-six carcasses were examined, 44 were necropsied. Cause of death was determined in 43 cases, 38 of which (88.4%) were due to anthropogenic trauma: 22 from entanglement (8 female, 10 male, 4 unknown sex) and 16 from vessel strike blunt trauma or propeller strike (9 female, 7 male). Notable gross and histopathological findings in entanglement cases included: constrictive wraps and deep lacerations caused by line primarily around flippers, flukes, and head/mouth; exuberant periosteal proliferation, lytic lesions, and osteopenia from chronically impinging line; dystrophic mineralization and traumatic scoliosis in a calf, which lead to compromised mobility; baleen plate disruption; poor body condition and heavy cyamid load in chronic cases. Blunt trauma findings included skull and vertebral fractures, well-defined regions of blubber and muscle contusion including undulating blubber hemorrhage, and suspected blood clots along the vertebrae, sites of fracture, and within body cavities. Propeller strike lesions included extensive lacerations in blubber, muscle, viscera and bone. These results demonstrate not only the profound physical trauma and suffering inflicted by human activities on individual North Atlantic right whales, but also the unsustainable cumulative impacts at the population level. Urgent and aggressive mitigation efforts throughout their range are needed to end anthropogenic mortality in this critically endangered species.
The authors would like to thank the right whale research and stranding response communities for their willingness to share data, photos, insightful observations, and expertise for this review study. Without the efforts of stranding networks to tow, land, transport, necropsy and dispose of these large whale carcasses, none of these data would be available. Thanks are also extended to Katie Gilbert, Kirsten Spray, and Ashley Powell for their assistance with data organization. Gaia Bonini provided the ArcGIS maps. The work was conducted under NOAA Marine Mammal Health and Stranding Response Permit #18786. This review study was also supported by funds from CINAR.
1. Pettis et al. 2018. North Atlantic Right Whale Consortium Meeting Annual Report Card. New Bedford, MA 7–8 November 2018.
2. Van der Hoop, J.M., Moore, M.J., Barco, S.G., Cole, T.V.N., Daoust, P.-Y., Henry, A.G., et al. 2013. Assessment of management to mitigate anthropogenic effects on large whales. Conserv Biol. 27,121–133.doi:10.1111/j.1523–1739.2012.01934.x
3. Knowlton AR, Kraus SD. 2001. Mortality and serious injury of northern right whales (Eubalaena glacialis) in the western North Atlantic Ocean. J Cetacean Res Manag Spec. Issue 2: 193−208.
4. Kraus, SD. 1990. Rates and potential causes of mortality in North Atlantic right whales (Eubalaena glacialis). Marine Mammal Science. 6(4):278–291.
5. Moore, MJ, AR Knowlton, SD Krauss, WA McLellan, and RK Bonde. 2004. Morphometry, gross morphology and available histopathology in North Atlantic right whale (Eubalaena glacialis) mortalities (1970–2002). J Cetacean Res Manage. 6(3): 199–214.