US Republican darling Sarah Palin is under fire for apparently clubbing a fish to death, then holding its still-beating heart in her hands for television cameras in what a US animal rights group calls a "snuff video".

Palin and her daughter Bristol were featured on a halibut fishing excursion for the ex-vice-presidential nominee's new reality TV show Sarah Palin's Alaska, which has premiered to record ratings in the US.

Cruel or humane? ... Sarah Palin goes halibut fishing on her reality TV show.

Halibut clubbing is standard practice among anglers, but Palin's apparent relish in the animal's suffering has outraged animal rights advocates In Defence of Animals.

The group claims the scene is "a snuff video" and says her lack of compassion is disgusting, particularly her lack of remorse. "Most disturbing is the way she seems to enjoy causing suffering to other beings," a spokesperson said.