New Zealand's 1867 trout introduction drove native fish to extinction

British settlers introduced brown trout to New Zealand in 1867 to promote sport fishing. Over the following years, more than 60 million trout were released into local waterways. The invasive species had a devastating impact on native fish populations, contributing to the decline and extinction of several indigenous species. Their presence also disrupted stream ecosystems and altered the behavior of local insects. Managing brown trout remains a major conservation challenge in New Zealand to this day.