Stopping stocking – a story 40 years on

Montana’s rivers and streams are on the ​‘bucket list’ of many fly fishers because of their fantastic populations of wild trout. It wasn’t always the case. Like many rivers around the world, they were heavily and sometimes indiscriminately stocked in a misguided attempt to promote fish populations. However, the vision of one fisheries biologist changed that policy. WTT’s friends at Salisbury & District Angling Club have just brought to our attention this video:

The video is based on work from the 60’s and 70’s by Richard Vincent, published in 1987, but his findings are as relevant today as they were then. Among the headlines…

- All experimental treatments were compared to control scenarios on similar stretches of the rivers in question to rule out or confirm whether it was stocking that was causing the effects observed.
- Most of the observed effects listed below under were on 2+ and older fish.
- When stocking of catchable size rainbow trout was stopped on the Madison River, wild brown trout abundance and biomass doubled; wild rainbow trout abundance was 8x higher, and biomass 10x higher.
- Winter river flow variation had little or no measurable impact on wild trout numbers during the same period.
- When catchable size rainbow trout were experimentally stocked for the first time into O’Dell Creek, for a period of three years, wild brown trout numbers decreased by almost 50%.
- Wild brown trout were more prone to movement during the stocking period indicating behavioural interaction and possibly displacement with the introduced fish.

Click here for a copy of the paper by Richard VIncent

Click here for more information on stocking, including case studies from fishing clubs who have stopped or reduced stocking.