Shenzhen's mayor has urged the bosses of state-owned firms in the city to volunteer for pay cuts and freeze bonuses after the sector reported double-digit declines in key measures of economic health in the fourth quarter of last year. The authorities said the city's power and water consumption, air and sea cargo volumes and truck traffic on expressways dropped by 10 to 18 per cent year on year in December. Officials said the slowing global economy had, for the first time in decades, shrunk profit margins at state-owned firms that operated power and water plants, ports, expressways and the city's airport. Mayor Xu Zongheng told a meeting that the 'most difficult time' would not end this year and bosses at state-owned firms should gear up for an even tougher situation with a clear awareness of the crisis, the Southern Metropolis Daily reported yesterday. Vice-mayor Zhang Siping said pay cuts were inevitable because of the worsening financial outlook, but the government would not impose a pay ceiling and the details could be decided by company boards. Mr Zhang said the city should follow the example of state-run companies in Beijing and Shanghai, where bosses voluntarily cut their pay packets by up to 40 per cent. 'State-run firms in Shenzhen are less able to withstand the financial crisis because of their size ... senior executives should demonstrate their determination and make concerted efforts to weather the difficulties,' he said. The mainland has proposed a pay ceiling for senior executives at domestic financial institutions and Shenzhen vowed to impose a similar pay ceiling to avoid unreasonably high pay at state-controlled financial firms. Official data showed that electricity consumption in Shenzhen dropped by nearly a fifth in December, while cargo volumes at ports and the airport decreased by 10 to 17 per cent. Experts said that an 18 per cent decrease in food consumption also suggested many of Shenzhen's 8 million migrant workers had moved away from the city. The government has also required company bosses to freeze entertainment expenditure and halve business trip budgets. Bosses from state-owned firms have been banned from squandering money on business conferences and overseas travel.