The deep-sea diving strategy of the long-nosed fur seal

Nature · Published 20 October 2026 · Updated 21 October 2026 Swipe more like this →

In short: While most fur seals stay near the surface, the long-nosed fur seal is a master of the deep. They can plunge into the ocean to depths of 380 metres, executing a complex foraging strategy that changes based on the time of day and the sex of the diver.

The long-nosed fur seal (Arctocephalus forsteri) exhibits remarkable diving capabilities compared to other fur seals. While a typical dive for these animals lasts only 1 to 2 minutes, males are capable of staying submerged for about 15 minutes at depths reaching approximately 380 metres (1,250 ft). Females can dive for about 9 minutes to depths of about 312 metres (1,024 ft), though their endurance increases significantly during the autumn and winter months.

Their foraging is dictated by 'diel vertical migration'—the daily movement of prey. During the day, these seals dive deeper to reach prey that has migrated down, while they return to shallower waters at night. This behavior creates a distinct spatial divide between the sexes: males typically forage over continental shelf breaks in deeper waters, while females utilize the shallower continental shelf. This separation reduces inter-sexual competition for food sources.

Lactating females must further adapt their behavior to balance hunting with parenting. They often take several long trips to locate prey patches before switching to shorter dives of about 5 to 9 minutes to exploit those areas. This specialized diving behavior is believed to be a primary driver of the sexual dimorphism observed between males and females of the species. These complex underwater maneuvers are essential for survival in the nutrient-rich but competitive waters of Australia and New Zealand.

The survival of these seals is currently threatened by human activity. While they are protected by various acts in Australia and New Zealand, they face significant mortality from commercial fishing gear, such as green trawl nets and plastic strapping tape. In some regions, it is estimated that over 10,000 seals may have drowned in such nets between 1989 and 1998.

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