"Truly anything you can think of has likely been found," he said.
Search missions resumed yesterday, following a cancellation of all search efforts on Tuesday because of poor weather conditions.
With the 24-hour delay in the search, those objects and possible debris from the plane could drift to an even wider area.
There are now 26 countries involved in the search.
"We've got to get lucky," said John Goglia, a former member of the United States National Transportation Safety Board.
"It's a race to get to the area in time to catch the black box pinger while it's still working."
Watch: Malaysian Flight MH370 crashed
The pinger could stop sending signals within two weeks.
A day earlier, angry relatives shouted "liars!" in the streets of Beijing about Malaysia's declaration that the plane went down with all aboard.
Although officials sharply narrowed the search zone based on the last satellite signals received from the Boeing 777, it was still estimated at 1.6 million sq km.
"We're not searching for a needle in a haystack; we're still trying to define where the haystack is," said Australia's deputy defence chief, Air Marshal Mark Binskin, at the RAAF Pearce military base in Perth.
The Australian Maritime Safety Authority, which is co-ordinating the search on Malaysia's behalf, said yesterday's search would focus on 80,000sq km of ocean about 2500km southwest of Perth.
The search for the wreckage and the plane's flight data and cockpit voice recorders could take years because the ocean floor was up to 7000m deep in some parts.
- additional reporting agencies