What If Gone

Species → Polar bear

Polar bear

Ursus maritimus

26,500 individuals
Extinction risk Vulnerable
Apex predatorArctic environmentMegafauna
Polar bear (Ursus maritimus)
Photo: U.S. Fish and Wildlife Service Alaska, Wikimedia Commons (Public domain)

What if it disappeared?

Impact Low
From one breeding season to the next

Polar bear reproductive success closely tracks the availability of young ringed seals — when these become scarce, bears shift strategy and target older seals, a sign of a tight link between the two populations, though it says nothing about what would happen in the other direction (the seal in the bear's absence).

Documented
Detail

Reimer, J.R., Brown, H., Beltaos-Kerr, E. et de Vries, G. (2019). Evidence of intraspecific prey switching: stage-structured predation of polar bears on ringed seals. Oecologia, 189(1), 133–148.

The authors document a shift in polar bear hunting behavior according to the age structure available among ringed seals, its primary prey — direct evidence of the fine-grained link between the two populations, measured rather than assumed by analogy with other apex predators.

Over several decades

What would become of Arctic marine wildlife (seals, fish, invertebrates) in the complete absence of the polar bear as a predator has never been measurable: no removal experiment is possible at the scale of the Arctic.

Insufficient
Detail

Unlike cascades studied through small-scale experimental removal (Paine's sea star, for example), regulation of seal populations by the polar bear across the entire Arctic remains a reasonable extrapolation from apex-predator theory, not a direct measurement.

Documentation

Last verified: August 7, 2026