"It was disgusting and showed a total lack of respect for the area, and for others who actually appreciate this place. It showed me that people were happy to take from the ocean, but didn't actually care about looking after it in return."
Mr Pettigrew said he decided to hold a community clean-up in the area this weekend. People were invited to join him from 9am on Sunday to help pick up rubbish.
"I've even been offered the help of some divers who claim that it's an absolute pigsty below the surface as well, so I'm really welcoming the extra help. I'd also ask that the public pick up what they can when they venture to the island, as long as it is safe to do so, and drop it in the bins on the boardwalk," he said.
"This rubbish, the fishing line in particular, is a real danger to wildlife as there are nesting penguins, as well as other sea birds, all around this area and they are susceptible to being caught up in this stuff. And then there are the seals, who I've also seen wrapped up in fish hooks. It's not nice to see, and can't be nice for the seals."
Mr Pettigrew, who is in his early 40s, said he did not want to be seen as a grumpy old man but something had to be done.
"The scary thing is that it's not even summer yet," he said.
Tauranga City Council solid waste operations engineer Murray Kliskey said the island got a fair amount of foot traffic.
However, there had been no complaints in the past year about litter.
Council contractors walked the island on a regular basis and collected small items of rubbish along the track, and community groups also did a great job during clean-up events, Mr Kliskey said.
"In the past year, we have been out a dozen times to remove larger amounts of rubbish located during staff inspections. This litter is usually left after parties, or in some cases, where people have been sleeping rough on Moturiki."
Mr Kliskey said he wanted to remind people "that we all play a part in preserving our environment and keeping our beaches beautiful".
"Think before you litter, and thank you to the many people out there who regularly collect rubbish."
Rubbish clean up of Moturiki Island
When: Sunday, September 11, 9am
Where: Moturiki Island, Mount Maunganui
Who: Anyone
Why: To help clean up the area of rubbish dumped
What to bring: Bags to collect rubbish in, gloves, suitable footwear.