Risk Factors for New Zealand Sea Lion (Phocarctos hookeri) Pup Mortality: Ivermectin Improves Survival for Conservation Management

Ivermectin treatment significantly reduces pup mortality in endangered New Zealand sea lions (Phocarctos hookeri) at Enderby Island, offering a potential conservation strategy. The study found that ivermectin-treated pups had 57% lower mortality rates compared to controls, particularly due to hypervirulent Klebsiella pneumoniae septicaemia—a leading cause of neonatal deaths since an epizootic in 2001–02. Researchers conducted case-control and cohort studies alongside a treatment trial over two field seasons (2016–2018), analyzing risk factors including bacterial carriage, body condition index, and hookworm presence. While the mechanism by which ivermectin prevents septicaemia remains unclear, preemptive anthelmintic treatment may limit systemic bacterial spread. This intervention could benefit larger colonies if applied broadly, though further research is needed to optimize its use for population-scale conservation.

Michael, S. A., Hayman, D. T. S., Gray, R., & Roe, W. D. (2021). Risk Factors for New Zealand Sea Lion (Phocarctos hookeri) Pup Mortality: Ivermectin Improves Survival for Conservation Management. Frontiers in Marine Science, 8. https://doi.org/10.3389/fmars.2021.680678