New Zealand released millions of brown trout; native fish paid the price

When British settlers packed thousands of brown trout ova onto ships bound for the Antipodes in 1867, they hoped to recreate the sport fishing they knew from Europe. Over the next five decades, acclimatisation societies bred and released more than 60 million brown trout into waterways across New Zealand. Today, that Victorian passion for fishing is seen as one of the most damaging biological invasions in New Zealand’s freshwater history. According to a major review published in Biological Conservation by Professor Colin R. Townsend, the spread of Salmo trutta caused severe declines in native fish, broke up their populations and led to local extinctions across both the North and South Islands. What began as a colonial project to create better fishing changed entire freshwater ecosystems.Colonial ambition and the 60-million trout campaignThe arrival of brown trout in 1867 was celebrated as a success for acclimatisation.