"The main cause of population decline used to be the usual suspects, such as rats and other invasive predators, but Whenua Hou is now predator free and we are not observing any population increase post-eradication efforts," Fischer said.
The young researcher spent last summer on the island, investigating terrestrial threats to the population, and found evidence suggesting that it was dune erosion, caused by storms and storm surges, that was having the biggest impact on the colony.
To get a better picture of what was happening to the birds when at sea - where they spent the majority of their lives - Fischer had tagged 10 birds with miniature global location sensing devices.
"Through these, we can assess pelagic distribution and infer corresponding threats," he said.
"Only when all threats faced by a species are understood, can we apply the appropriate conservation management."
To raise funds and more awareness of the work, Fischer has joined a global crowdfunding challenge for seabird research through the online platform Experiment.
The goal was to attract the largest number of backers, with the project that secured the most winning additional funding from the platform.
"What I like about the crowdfunding platform is that it allows for the general public to look over the shoulder of scientists as the work progresses," he said.
"We, the scientists, keep everyone who backed the project up to date through lab notes, and this really enables people to get more involved with the project."
Another nice point about the challenge was that it took focus away from money; it was more beneficial for 20 people to donate $1 than for one person to donate $20.
"This in turn allows for more people to get involved with the project and seabird conservation."
While New Zealand was known as the seabird capital of the world, his project was the only Kiwi effort taking part in the challenge.
"Therefore, I'm representing New Zealand seabird conservation within this challenge."
So far, the project was one of the front runners out of 17 competing, but Fischer hoped to get more Kiwis backing the cause before the challenge closes tomorrow.
They can do so by visiting www.experiment.com/divingpetrels.