Mr Stewart, a Southland Fish and Game senior officer, said being a trout fisher, he knew there were real benefits in getting out and catching trout and he had wanted to know more.
"I came across a technique known as forest bathing, which is a Japanese technique where people go out into the forest and they just basically immerse themselves in the natural environment," he said.
"There’s been quite a bit of science done about that, and what we’re able to show was that when people go out into these natural environments their cortisol levels drop, as do their stress hormone levels," he said.
"Then exposure to blue spaces as well — so that’s rivers, oceans, wetlands — that all can also have positive effects at a physiological level on our health and wellbeing.
"I thought, well, trout fishing being an activity that exposes people to both, you know, forest and green space environments as well as blue space environments, often at the same time, surely that’s got to have some sort of benefit there.
"That’s I suppose where it all started, and of course being a trout angler myself, I was obviously interested from that perspective as well."
A small group was initially surveyed, which led to a countrywide study of nearly 1900 anglers, one of the largest of its kind globally, which had shown fishing could significantly boost wellbeing and mental health.
The study, which was published in the international journal Leisure Sciences, said active anglers were 52% less likely to report psychological distress or thoughts of self-harm.
Mr Stewart said trout fishing developed social connections, which were very important for mental health.
Fishing also engaged multiple senses — walking, differing temperatures, the sounds of birds and the environment — so it was an immersive experience.
"That connection to the nature element, I think, is also important. And I guess as well, the fact is that it’s pretty clear in the literature that if you do exercise, you get improvements in mental health — that’s pretty well established — and trout fishing is conducive to exercise."
Fishing was a way to get out and about and the results of the survey were what he expected. He said fishing was good for young people and a couple of schools had set up fishing clubs to get people into it.
University of Otago senior research fellow Dr Shyamala Nada-Raja was approached by Mr Stewart to help in the survey.
Dr Nada-Raja, a wellbeing and suicide prevention researcher from the University of Otago, said the findings could reshape approaches to mental health support.
"What we’re seeing here is evidence that nature-based interventions like trout fishing could serve as valuable complements to traditional mental health treatments," Dr Nada-Raja said.
"Some people who might not access conventional counselling services may find heading out to a river for a few hours both appealing and beneficial."
About 140,000 fishing licences are sold annually, anglers spending over a million days fishing New Zealand’s waters.
