New Zealand seas are teeming with unidentified creatures which may have properties ranging from combating pollution to fighting cancer, say scientists involved in a project to catalogue marine life.

But a shortage of experts and funding to describe new species is hindering understanding at a time when ecosystems face growing threats from over-fishing, pollution and climate change.

The capacity to scientifically describe new species is at its lowest since World War II, says a report on New Zealand's marine biodiversity for the international Census of Marine Life project.

Scientific classification by taxonomists is an essential first step for applied research, says Dr Alison MacDiarmid, a contributor to the project and marine ecology group manager at the National Institute of Water and Atmospheric Research (Niwa).

"Just knowing what you've got is always the first step to doing anything. You can't understand how they can help you until you know what you've got."

But she says taxonomy is not seen as "new and sexy" by funders, and policy makers and students no longer see it as a career.

Dr MacDiarmid says taxonomic funding has been static under theFoundation for Research, Science and Technology.

But Justine Daw of the foundation disputed Dr MacDiarmid's funding claims.

In October last year, Niwa's marine taxonomy database received a boost totalling $3.4 million - to be paid at $340,000 a year for 10 years.

Another long-term project, a bio-security research programme, received extra money in 2008, she said.

New Zealand is one of 25 marine regions which this week released inventories of marine biodiversity for the 10-year census project, which ends in October.

The New Zealand report says a quarter of 17,000 species collected in our exclusive economic zone have yet to be described.

It suggests a further 17,000 species - most in depths beyond 2000m - have yet to be discovered.

The report says New Zealand has 62 marine scientists capable of identifying marine organisms, but only 29 who regularly describe new species.

Auckland University marine scientist Mark Costello co-authored a global summary of the regional stocktakes, which found that worldwide taxonomic shortages are hampering the ability to understand species of economic and ecological importance.

"There is a need to accelerate the discovery of marine biodiversity, since much of it may be lost without even being known."