Rare Record of Albinism in a New Zealand Fur Seal (Arctocephalus forsteri) Pup With Observations Through the Weaning Period.

The rarity of heritable pigment anomalies in marine mammals makes it challenging to assess their fitness ramifications. Potential negative effects include reduced visual acuity, greater predation risk, increased disease vulnerability, lower fertility and decreased heat absorption. Logging instances of heritable pigment anomalies can improve understandings of their impacts and potentially permit their use in understanding metapopulation dynamics. We report on a rare observation of albinism in a male New Zealand fur seal/kekeno (Arctocephalus forsteri) pup. The pup was discovered near Kaikōura during colony monitoring in February 2025. He had honey-coloured natal pelage, bluish-white pupils, white/translucent whiskers and pink skin on his flippers, nose, ears and around his eyes. He appeared to experience reduced visual acuity. When observed on September 1, 2025, the pup lacked muscle tone, potentially a result of his eyesight precluding typical muscle development behaviours. His survival chances postweaning may be reduced by his poor eyesight, although a previous record of albinism in a subadult conspecific demonstrates postweaning survival is possible. While abnormally pigmented individuals from other Arctocephalus species have typically been sighted at remote colonies where year-round observations are not possible, this birth in central mainland New Zealand provides opportunities for longitudinal tracking.