Cryptorchidism in the sub-Antarctic fur seal Arctocephalus tropicalis

The prevalence of cryptorchidism, a condition when one or more testes failed to move to their proper position(s), was evaluated for sub-Antarctic fur seals from Gough Island, South Atlantic. The reproductive tracts of male fur seals (n = 123) were examined and reproductive organs measured in a previous study. Only one fur seal, a 5-year-old sexually mature male, had one inguinal testis on the right side, and a small abdominal one situated below the kidney on the same side. A matching contralateral testis could not be located, neither in the scrotum or inguinal canal nor within the abdominal cavity. Amongst pinnipeds, cryptorchids rarely occurred in northern fur seals (0.01% to 0.02% prevalence), harbour seals (undetermined prevalence) and in sub-Antarctic fur seals (0.8% prevalence). Inconsequential on a population level, the rare instances of cryptorchidism in seals are interesting curiosities.