Researchers off the Azores filmed an unusually pale shark with a BRUV system (Baited Remote Underwater Video): a leucistic false catshark (Pseudotriakis microdon). The baited camera, filled with salted, chopped sardines, recorded for about nine hours. In a roughly 30-second clip, an almost white animal passed along the edge of the frame – a discovery of scientific first significance.
Leucism instead of albinism
The false catshark is a large deep-sea predator with a patchy global distribution and normally dark brown to blackish coloration. The observed specimen shows leucism: a genetically caused, partial reduction of skin pigmentation with normal eye color. This distinguishes it from true albinism, which involves a complete lack of pigmentation including the eyes.
— Shark Diving (@scuba_sharks) September 3, 2025
Leucistic animals appear white or pale but retain their normal eye color – unlike albinos.
Rare condition, healthy animal
Pigmentation disorders such as albinism or leucism are rare in cartilaginous fish. It is often assumed that the pale coloration could impair hunting and camouflage. In this case, however, the shark appeared in good condition: the clearly rounded belly suggests it had recently fed – or was pregnant. In great depths, many fish are naturally pale-colored; additional disadvantages are therefore unlikely.
Deep-sea context and study
Der Nachweis gelang im Oktober vor den Azoren in über 1.200 Metern Tiefe. Die Inselgruppe liegt etwa 900 Meilen westlich des portugiesischen Festlands. Die Ergebnisse wurden am 6. August im Fachjournal Marine Biodiversity veröffentlicht; beteiligt waren u. a. Diana Catarino, Eva Giacomello, Pau Robles und Laurence Fauconnet.
