EDMONTON -- Scientists raising questions about the ethics of Alberta's wolf cull are calling it cruel and unnecessary.

Conservation biologists have published a letter in a scientific journal about the program, which has killed hundreds of wolves in an attempt to help caribou numbers in west-central Alberta.

The letter says university and government scientists who used the cull to gather data on its results violated professional ethics.

But a government biologist says there's no other way to keep wolf numbers low enough to help caribou other than by shooting the predators from helicopters or poisoning them.

Dave Hervieux says stopping the cull would doom the herds and he makes no apology for using the information it generated to gauge how successful it has been.

That research showed that killing wolves has stabilized caribou numbers, but barely.

It concludes the cull won't stop herds from disappearing if their habitat isn't protected from the energy and forestry industries.