The hoax sale of a dolphin on the Trade Me website has angered the SPCA, which says it has never been inundated with so many complaints.

The "seller" from West Auckland claimed the dolphin was being kept in a domestic swimming pool after being accidentally caught in a net during a weekend fishing trip.

SPCA national chief executive Robyn McDonald said the hoax was an irresponsible attempt at self-promotion at the expense of New Zealand's international reputation as a nation that cares for animals.

She had received hundreds of concerned emails and telephone calls.

"While the majority of these simply expressed their concern, there were also comments along the lines of Kiwis will sell anything. Even though the posting has now been revealed as a hoax, our national reputation will still have sustained some damage.

"We understand that the hoaxer is now offering to recompense the SPCA for the trouble he has caused. While his donation will be welcome, he should have considered the damage he was likely to inflict before indulging in this totally irresponsible attempt at self-promotion."

Peter Younger, a senior Department of Conservation investigator, said he was also annoyed at having to waste his time investigating the hoax.

Mr Younger had talked to the offender, an Auckland advertising manager, who had expressed some regret but was surprised at people's gullibility.

"He could not believe the fuss."

He had previously investigated similar hoaxes about the proposed sale of a brown kiwi and penguins.

Mike O'Donnell, of Trade Me, said the hoax was removed from the site within 40 minutes.

He said Trade Me employed 20 people to check postings on the site.