ADFG’s Photocensus Of Porcupine, Central Arctic Caribou Herds Sees Declines

Alaska Department of Fish and Game’s completed photocensus of two Alaska caribou herds saw declines in both. Here’s the press release from ADFG:

ADF&G completes photocensus for the Porcupine and Central Arctic Caribou Herds in summer 2025

(Fairbanks) A photocensus of the Porcupine caribou herd (PCH) was completed on July 4, 2025, and resulted in a population estimate of 143,000 caribou. The following day, a photocensus of the Central Arctic caribou herd (CAH) was completed and resulted in a population estimate of 26,600 caribou.

Both herds have declined since their previous photocensus estimates and the declines were expected based on annual monitoring of adult survival, parturition (pregnancy) rates, and calf survival.

Porcupine caribou herd summary

The 2025 PCH photocensus estimate of 143,000 caribou is lower than the previous photocensus in 2017. The 2017 photocensus estimate was 218,000 caribou, which was the most caribou ever estimated in this herd since monitoring began in the 1970s.

This herd has experienced periods of growth and decline since photocensus efforts began. In 1979, the herd was around 106,000 caribou, grew to 178,000 in 1989, declined to 123,000 in 2001, and then increased to 218,000 in 2017. This current period of decline is steeper than was observed during the decline in the 1990s.

A reduction in adult survival, calf survival, and other population metrics since 2017 supports the photocensus results that the herd is in a decline. Future photocensus population estimates and monitoring of the herd will continue to document the nature and duration of this decline.

Central Arctic herd summary

The 2025 CAH photocensus estimate of 26,600 is lower than the previous photocensus in 2022 which estimated 34,600 caribou. Previously, the CAH experienced a population peak in 2010 at 68,400 caribou and then declined to 22,600 in 2016.

Similar to the PCH, reduced adult survival, calf survival, and parturition rates support the photocensus results indicating that the CAH is no longer growing and has declined since 2022

We will continue to monitor the survival and parturition rates and conduct a photocensus on both herds when possible. Large migratory caribou herds rarely remain stable over long periods of time and instead exhibit phases of population increases and declines.