His group had tried to bring in nets as evidence of poaching after police dismissed their concerns.
He had made offerings to a portrait of the Dalai Lama and commemorated a 2007 US congressional award to the exiled spiritual leader.
Hundreds gather in defiance of Chinese bans to honor the exiled Tibetan spiritual leader.
His arrest comes as authorities clamp down on celebrations in Tibetan-populated regions of China.
The event is observed with fireworks and with prayers in public gatherings and private homes.
Four are later released, though one is severely beaten while in custody.
The move comes as authorities restrict public gatherings in the run-up to the birthday of exiled Tibetan spiritual leader the Dalai Lama.
The move restricts the numbers living at Nyatso Zilkar monastery in protest-hit Yulshul prefecture.
Authorities ban the gathering of crowds who might proclaim their support for the exiled spiritual leader.
Their families have not yet been told what charges they face or where they are being held.
As demand and prices fall, traders turn the once sought-after dogs out to fend for themselves.
At least 10 are detained as police scatter protesters from land used by Tibetan villagers.
Relatives and friends celebrate their return to their home village in Sichuan's Ngaba prefecture.