New Zealand urgently needs a national ocean strategy to sustainably manage and use its extensive marine resources to boost the economy, the head of the country's National Institute of Water and Atmospheric Research ( NIWA) said Thursday.

NIWA chairman Chris Mace said New Zealand had "huge untapped potential" in its ocean and coastal waters, and the government had clearly indicated its intention to increase use of those resources.

"Under the current global economic environment, I think that is prudent. But without an integrated ocean's strategy, our ability to sustainably manage those resources will clearly be compromised, " Mace said in a speech to the New Zealand Marine Sciences Society Conference.

Without a strategy, New Zealand marine management would remain fragmented, with agencies managing marine activities in a reactive way, under different laws and management regimes, he said.

"New Zealand needs an ocean's strategy that balances competing needs, focuses our science on understanding the interlinked processes of ocean's ecosystems, and sets a clear direction for how we use and manage our extensive marine resources," said Mace.

"We need evidence-based policy that coordinates the way we use marine resources to enhance our economic prosperity, while at the same time ensuring the environmental impacts are minimized."

Without a strategy, the cumulative environmental effects could be "catastrophic," he said, "and could eventually constrain any further economic growth from our marine resources."

More than 150 marine scientists, local and central government representatives, industry members, university staff, and students are attending the New Zealand Marine Sciences Society Conference on Stewart Island.

In 1978, the United Nations Conference on the Law Of the Sea extended New Zealand's territorial waters extensively, giving it the fourth largest maritime jurisdiction in the world with a 200- nautical-mile (370 km) exclusive economic zone covering 4.83 million square km.