Long-term Monitoring Projects
Long-term Monitoring: River Wylye (Hampshire Avon)
The Wylye Grayling and Trout Survey (WGTS) has been monitoring grayling and brown trout populations since 1996 at multiple long-term sites on the River Wylye, Wiltshire. It is a collaborative project between Natural Resources Wales, the Piscatorial Society and the Game & Wildlife Conservation Trust, supported by the Grayling Research Trust and Wessex Water plc.
Location of the River Wylye in the Avon Catchment and wider UK (inset map)
Annual surveys take place in autumn each year. Quantitative electro-fishing is used to estimate the abundances of all grayling and trout age classes, and data are collected on each captured individual’s condition, including a scale sample that is used to verify their age. Captured grayling are tagged to identify individuals that may be recaptured in subsequent annual surveys. This is done with a combination of visual implant (VI) and passive integrated transponder (PIT) tags.
Electro-fishing team surveying grayling and trout in the River Wylye
The WGTS is thought to be the most comprehensive and consistent grayling population survey in Europe. The data it yields are crucial in developing a better understanding of the drivers of change in the Wylye grayling population. Long-term patterns indicate a recent decline in Wylye grayling, but an increase in Wylye brown trout. Completed research projects aimed to identify which environmental factors are causing the changes in these populations, through influences on grayling recruitment, growth rates and survival, and how we might manage river habitats to conserve both fish species more effectively.
Learn more about the WGTS and research findings below:
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