The International Union for the Conservation of Nature (IUCN) lists the masked booby as a species of least concern, though the population worldwide is decreasing. At Clipperton Island, the colony was benefitted by the presence of yellowfin tuna (Thunnus albacares), which drove their prey item—flying fish—to the surface, facilitating predation by boobies. It may be that overfishing of tuna adversely impacts the availability of fish there. In 2005, 508 young masked boobies at the colony suffered from angel wing, a congenital deformity of one or both wings resulting in flightlessness. This coincided with a season of high nestling mortality that was likely related to low numbers of yellowfin tuna due to possible overfishing at a crucial time in the breeding season. The warm phase (El Niño) of the El Niño-Southern Oscillation in 1982 and 1983 negatively impacted breeding on Christmas Island as the higher water temperatures reduced food supply. Where usually 1500 pairs nested, no young were observed over this period; 50-60 pairs were observed breeding in October 1983. The Australian government has rated both subspecies occurring in Australian waters as vulnerable to climate change. The low-lying colonies of subspecies personata are at risk from rising sea levels, and the rising sea temperatures are calculated to reduce food productivity, which may impact on breeding success of both subspecies.