Taronga had a performing polar bear act in about 1965, presented by a German professional trainer named Alfons Arndt.
He had been contracted by Taronga to train their newly acquired dolphins. Dolphins were the "hot" new species in Australia at that time, and a number of commercial marine parks were established along the eastern coast of Australia in the 1960s to display them. Taronga's seal pool had been deepened to allow the keeping of dolphins, but unfortunately their mortality rate was rather high and so they weren't the fashionable species for too long.
Taronga had always had a small circus consisting mainly of dogs, ponies and monkeys, but things got a lot wilder when Alfons Arndt developed both a lion act and a polar bear act for it. The lion act was, I think, 8 young lions which performed a standard, circus type act. The polar bear act (which I saw only once) consisted of 4 or 5 bears, if memory serves me right, which did a fairly basic act (sit-ups, slippery-dip etc.) Polar bears are regarded as the most dangerous large carnivores to train, and the fact that Arndt presented the act for a couple of years and lived to tell about it was a triumph in itself.
Now for the gaps which I can't fill in; Where did the bears come from? They were presumably young animals sourced via American zoos. They weren't Taronga's "regular" polars, which remained in the bear pits in the lower part of the zoo during this time. Where did the bears (and indeed Alfons Arndt) go when his contract expired? (They didn't remain at Taronga.) Steve Robinson could probably shed more light on this. (Come on Steve - write the book!)
Probably the most famous of the old-time polar bear trainers was Willi Hagenbeck of the famous German zoo and circus family. During the wars he regularly presented an act consisting of 18 polar bears in Europe. On one occasion he presented 60 polar bears in the one ring. He was occasionally attacked by his bears, but managed to survive. The German/American tiger trainer Charly Baumann, in his book "Tiger Tiger" wrote; "Hagenbeck's lameness was the result of a polar bear attack early in his career. During this or another assault, I was told, he was also castrated by a bear.....castration has been feared by men working with polar bears because the animals often attack a man's stomach and genitals."