STOPPING dredging work on a new dock on Southampton Water for four months of the year to avoid damaging salmon stocks would cost millions, a public inquiry has been told.

The inquiry into Southampton Docks operator Associated British Ports' plans for a new container terminal between Hythe and Marchwood yesterday begun dealing with fisheries issues.

Some of the of the questions put to ABP marine environmental expert Ian Townend surrounded calls for the massive dredging operation to be halted at the times of year when salmon are moving past the Bay.

One suggestion was that dredging, which could go on for several years, could be halted from April to July. Another was that it could stop from mid-March to mid-September.

But Mr Townend told the inquiry that stoppages would extend the length of time the dredging took by two years for the four-month stop and by three years for the six-month stoppage.

"For a four-month stop period, the additional cost is likely to be between £30m and £50m and for a six-month stop it is likely to be between £40m and £70m," he said.

He made reference to pile-driving and dredging work carried out between 1968 and 1978, when the existing container terminal in Southampton's Western Docks was being built.

"The construction was carried out along a narrow reach, along which the salmon had no alternative but to pass," he said, adding that there were probably high levels of sediment suspended in the water at the time.

He added that the variations in salmon populations in the Test were similar to national trends

Mr Townend also unveiled major projects which ABP was prepared to fund and were aimed at helping salmon conservation programmes.

Two of them, he said, were fish tracking programmes aimed at proving that the construction work and the altered shape of the bed of the estuary did not present a barrier to migrating salmon. Its ten-year monitoring programme was likely to cost between £360,000 and £500,000.

He said ABP intended to fund the provision of egg incubator boxes on the Test and Itchen Rivers to increase the survival rate.