They show that while demand for section 457 visas had declined in most sectors with the slowing economy - visa applications from mining companies are down 15 per cent so far in 2012-13 - that is outweighed by surging demand in other industries that seems at odds with what we know about how they are faring. For example: Until mid-2011, few firms used 457 visas to import cooks; in 2010-11, just 45 visas a month were issued for skilled kitchen staff. Yet by January this year, 1690 cooks had been granted 457 visas, 240 a month. Cooks have suddenly become the biggest users of section 457 visas. Why? It's not because of any surge in demand. The Bureau of Statistics estimates that spending in hotels and restaurants fell 1.1 per cent last year, as Australians economised on discretionary spending to avoid more debt. Where is the labour shortage that requires us to suddenly import thousands of foreign cooks? It's not just cooks. This year alone, the number of chefs, their superiors, entering on 457 visas has shot up 150 per cent to almost 90 a month. Imports of cafe and restaurant managers have quintupled, from 27 a month to 134 a month. Does anyone smell a rat here?

Retailing is also going through hard times. At last count there were 26,000 fewer Australians working in shops than in 2008. Yet some retailers claim they cannot find Australians to staff their stores; in 2012-13 they imported 300 foreign workers a month just to be shop assistants. Explain that! It might make sense if they were in WA mining towns, but no: overwhelmingly, the new workers are serving in shops in Victoria and NSW. In both states, the numbers of temporary foreign workers brought in for retailing has doubled since 2010. Take a sniff of that! Then there is the category called ''other services'', which is dominated by hairdressing. Since mid-2010, the number of foreign workers given 457 visas to work in hairdressing salons and the like has jumped from 5010 to 12,400. In Victoria, their numbers have almost trebled. Why? We have no shortage of trained hairdressers in Australia, but they get trained and then leave because the pay is lousy. That's a structural problem, and the market can fix it by raising their pay. For Australian workers, pay usually rises. For workers on section 457 visas, it is falling. Since mid-2011, their average pay has shrunk from $96,800 to $89,900. Maybe that is partly due to some negotiating contracts in foreign currencies which have fallen against the Australian dollar, but can that explain why the average pay for technicians and trade workers has fallen from $73,400 to $69,200? Or the average manager's pay cut from $148,800 to $123,900? Australia has gone through two years of slow jobs growth, with total jobs growing less than 1 per cent a year. Yet applications for section 457 visas shot up 33 per cent in 2011-12, and are up another 10 per cent this year, to record levels.

Yet just as industries are showing different trends - most using fewer section 457 visas, but a handful suddenly demanding more - so different countries are showing very different trends. In 2012-13, skilled migration has declined markedly from Britain, the US, Canada, Germany, South Africa, etc. But in a slowing economy, skilled migration has risen sharply from Ireland, for obvious reasons, India, China, South Korea - and Nepal. Yes - poor, backward Nepal is now one of the 15 main sources of ''temporary skilled migrants'' to Australia. If that were true, we should be ashamed at luring away their potential leaders. But we've been here before. In 2008-09, Monash University demographer Bob Birrell exposed the rorts of the student visa program, in which unskilled Indians and Nepalis were lured to study low-level TAFE courses as cooks and hairdressers as a back door to gaining permanent residence.

Now Birrell and fellow researcher Ernest Healy have pointed out in two papers - Immigration Overshoot and The Impact of Recent Immigration on the Australian Workforce [on the web at http://arts.monash.edu.au/cpur/] - that we are seeing the same trends again. And that requires reforms. The fact that the 457 visa program generally works well does not mean that there is no rorting taking place. The fact that rorting is taking place does not mean that the program does not generally work well. The statistics suggest both are happening now. These are modest, sensible reforms to protect the integrity of the program. The government is trying to fix the rort - as it must. Tim Colebatch is The Age economics editor.