The ultimate dilemma for conservationists...

Conservationists have found themselves the ultimate dilemma - marine biologists are discussing the possibility of a cull of the orca - the killer whales that are destroying other endangered mammals.

They are becoming deeply concerned about new research which suggests a link to a huge population slump in other species such as sea otters, stellers sea lions and harbour seals through the changed eating habits of orcas.

The main prey of the orcas has traditionally been great whales such as the grey and sperm whales, but hunting by humans has cut the numbers of a lot of these species to far below their natural levels.

Culling these orcas