Fewer than 5 per cent of children and young people speak Gaelic - not much more than "a blip on the chart", Kenneth MacKinnon, of the Celtic department at Edinburgh University, said.
The annual rate of loss of Gaelic speakers has been halved from 1,300 to 700 but more are dying than take up the language, Professor MacKinnon said.
Not since 1921 had Scotland achieved the target of having a third of under-25s able to speak Gaelic, the "platform for the next generation".
He envied the situation in Wales where the language was compulsory and pupils were bilingual by the time they left school. "Wales is a quantum leap ahead," he said.
In 1991, Wales achieved the target of a third of under-25s able to speak their native language and the figure is now 43 per cent.
Professor MacKinnon, a Cockney with a Scottish heritage, advised ministers to establish Gaelic policies for the whole of Scotland and to support families and communities, not particular areas. Two-thirds of Gaelic speakers live outwith the Highlands.
"We do not need to have Indian reservations," he warned.
Census returns showed that Gaelic was reviving throughout the country, although in the heartlands of the Western Isles the number of speakers was falling proportionately with each generation. "We do not know what turns people on to speak Gaelic and what turns them off," Professor MacKinnon said.
He supported the contention that Gaelic had to be a living language in a modern world based on human rights. Without policies for full bilingualism, the number of speakers would continue to decline.