Whaling bans are helping some whale populations recover, but other species are still in serious trouble, Conservation Minister Steve Chadwick says.
The International Union for Conservation of Nature (IUCN) said some large whale species such as the humpback, minke and southern right whale were recovering from a threat of extinction.
A review of cetaceans -- grouping about 80 types of whales, dolphins and porpoises -- showed many small species were still at risk. Entanglement in fishing gear was the main threat.
Ms Chadwick said stepping back from extinction was good news but there was a long way to go.
"This still does not mean that we have a healthy, viable population with anywhere near historic population numbers," she said.
The IUCN said recovery in some species was mainly due to them being protected from commercial whaling.
The world imposed a moratorium on hunts of whales in 1986 after many were driven towards extinction by decades of commercial exploitation for meat, oil and whalebone. Minke whales are still harpooned by Japan, Norway and Iceland.
"While the improvement for humpback and southern right whales is positive, there is still a need to foster population recovery, and an international effort is needed," Ms Chadwick said.
"We must remember that although the international population is making a comeback, some Pacific groups of whales remain in a perilous state."
She said more data was needed for species whose status was unclear.
The IUCN had a "red list" of endangered species. The humpback whale, which grows up to 15m and is found in all the world's oceans, was moved to "least concern" from "vulnerable" on the new red list.
The southern right whale, found in the southern hemisphere, and the common minke whale, living in the North Pacific and North Atlantic, were shifted down to the "least concern" category from the "lower risk" grouping.
The minke rating was changed because of better information, not improved stocks.
There was not enough information on the Antarctic minke whale, which is caught by Japan, to judge how many there were.
Norway has set a quota of 1052 minke whales and Iceland 40 in the north Atlantic in 2008. Japan caught 551 minke whales off Antarctica in the past season.
The blue whale, bigger than any dinosaur and the largest creature ever to have lived on earth, remains "endangered" along with the fin whale and sei whale.
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