Ghost Fishing NZ and Sustainable Coastlines work on cleaning up the harbour near Frank Kitts Park in Wellington.

Rubbish clogging the capital's waterways harms marine life and while the tonnes of waste thrown into the Wellington Harbour is decreasing, our littering ways remain.

Wellington Harbour Clean Up event coordinator Sharon Powick said Saturday's annual event attracted 35 scuba and free divers and a team of about 40 helpers who pulled up everything from an Onzo bicycle, 45 road cones, old tyres, shopping trolleys, phones, clothing and general rubbish to items such as cans, bottles and plastic.

In its sixth year, Powick said the volunteers would easily fill a skip bin with rubbish but the amount pulled out of the waters each year had decreased from the 40 tonnes of rubbish collected in 2013.

MONIQUE FORD/STUFF Divers were given "catch bags" to fill underwater. They were brought to the surface and collected by a team of helpers who sifted through the contents for marine life.

Despite efforts to educate people about the adverse effects foreign items had on the natural environment, Powick said it shocked her every year how much and what people dumped into New Zealand's waterways.

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"We've got so much rubbish coming up. We're running out of helpers."

MONIQUE FORD/STUFF An Onzo bicycle was found in the Wellington Harbour while divers searched for and collected rubbish at the annual Wellington Harbour Clean Up.

But there is some good news. There had been a noticeable difference in the number of marine species found in Wellington Harbour, she said.

"There's been an increase in the number of stingrays in the lagoon. They have been breeding more.

"We're seeing a decrease in the amount of rubbish in the harbour since we started which is fantastic."

Some of the items pulled out of the water at the weekend had been in the harbour for years, buried in the silt.

MONIQUE FORD/STUFF Scuba divers search and collect rubbish in Whairepo Lagoon for the 2019 Wellington Harbour Clean Up.

A number of old tractor tyres, thought to be part of an old retaining wall, were cited by divers. A barge was due to help remove them, however strong winds meant the job had to be postponed.

Divers were given "catch bags" to fill underwater. They were brought to the surface and collected by a team of helpers who sifted through the contents for marine life.

The Island Bay Marine Education Centre set up tanks to house some of the marine life and educate the public about the creatures living in our seas such as sea snails, crabs and starfish. Other marine animals were immediately returned to the sea.

MONIQUE FORD/STUFF In its first year the Wellington Harbour Clean Up found 40 tonnes of rubbish thrown into the waterway.

Powick said it was great to see so much help from the public each year and thanked everyone part of this year's efforts.

Over the years there were some lucky saves as well, she said. A couple of holidaymakers managed to revive photos from cameras accidentally dropped into the harbour.

Wellington City Council has donated the skip bin which will be filled, collected and taken to a landfill. The Wellington Harbour Clean Up 2019 was supported by Ghost Fishing New Zealand and Sustainable Coastlines.