To the naked eye, they look like tiny indistinguishable pellets that could easily be mistaken for organic matter.

Plastic fragments in the world's oceans are insidious killers which are steadily claiming an increasing number of bird and marine life every year.

But on the New South Wales north coast, a small group of scientists and volunteers are leading a campaign to reverse the trend in the local area.

Every week, up to a dozen sick or injured seabirds are brought to the Australian Seabird Rescue centre in the town of Ballina, where staff try to nurse them to better health.

Marine ecologist Jann Gilbert said hundreds of these birds do not survive and an increasingly common culprit is to blame.

"Plastic, lots of plastic," Ms Gilbert said, as she dissected a dead Shearwater's gizzard, revealing a collection of brown pearly fragments.

Marine ecologist Jann Gilbert said hundreds of sick or injured seabirds do not survive and plastic was to blame. ( ABC: Bill Birtles )

"There's a very good chance, because of the size of the plastic and the tiny size of the opening that goes to the digestive tract, that this bird wouldn't have been able to digest anymore."

The bird is just one of hundreds taking up freezer space at the rescue centre, where necropsies (animal autopsies) are performed to document what is killing the local birdlife.

"It's a horrific death for a bird to starve or dehydrate or a combination of both," Ms Gilbert said.

"The bird's got no way of being able to regurgitate the plastic or move it through.

"Imagine being out in the middle of the ocean, slowly starving and dying of thirst."

99pc of seabirds will ingest plastic by 2050: report

The increase in plastic ingestion seen at the centre correlates with a CSIRO-led global report that paints a worrying outlook for the world's seabird species.

The study estimated that 60 per cent of the world's seabird species are already ingesting plastic, but by 2050, 99 per cent of species will be affected.

Chris Wilcox from the CSIRO's Marine and Atmospheric Research Centre in Hobart co-authored of the report.

"It's basically driven by the fact that plastic production is increasing exponentially," Mr Wilcox told 7.30.

"Every 11 years we make as much plastic as we've made in the entire time since it was invented. The birds are basically tracking that pattern.

Chris Wilcox co-authored a CSIRO-led global report estimated that by 2050, 99 per cent of the world's seabird species will be ingesting plastic. ( ABC: Bill Birtles )

"The world has lost about 60 per cent of the seabird populations that we had in 1950. Plastics is probably one of the main contributors to that."

The report identified the southern Tasman Sea as a particularly dangerous spot, where seabirds are increasingly coming into contact with plastic and mistaking it for food.

A different study released last year by the CSIRO estimated there are 150 million pieces of litter strewn around Australia's coastline, the majority of it plastic.

Having seen the devastating effects it can have on birdlife, staff at the Seabird Rescue Centre also organise weekly patrols of the estuaries in Ballina, cleaning up the plastic cups, chocolate wrappers, bag ties and other pieces of packaging they regularly encounter.

Seabird Rescue Centre general manager Kath Southwell said they hope to remove as much plastic as possible before it breaks apart in the tiny pieces that birds, fish and turtles accidently consume.

Some estimates for plastic ingestion by turtles in Australia range as high as 52 per cent, making it a contributor to the endangered status of the Green Sea turtle and the critically endangered Hawksbill.

But as long as global plastic production continues to increase, local efforts to rid it from the oceans will only go so far.

"We're seeing more and more animals suffering," Ms Southwell said.

"There has been a definite increase in the number of turtles being brought in and other species coming into care — it gets worse year and year."