NEW research has revealed salmon numbers are falling in Dorset.

The Game & Wildlife Conservation Trust (GWCT) has revealed warmer winters and cooler springs could be driving the fall in numbers.

Experts from the Trust studied the River Frome in Dorset and found numbers of juveniles, also referred to as parrs, were lower following unseasonal temperatures, which could be associated with climate change.

Dr Jessica Marsh, who led the GWCT research, said: "Our findings highlight that changes to seasonal temperatures in chalk streams – groundwater-fed rivers are considered stable in their thermal regime compared to more dynamic rain-fed rivers – can have detrimental impacts on juvenile salmon recruitment in these systems."

However, at the end of last year the number of young salmon (smolt) leaving the River Frome to migrate to the sea for the first time was the highest in eight years.

A parr is the fourth stage of the life cycle of an Atlantic Salmon, while a smolt is the fifth stage.

Figures released by the GWCT showed more than 13,000 smolts - the stage in the salmon lifestyle when it is ready to migrate to the sea - passed the monitoring station in the river this spring, which experts believe may be due to the size of the smolts.

This figure is 40 per cent higher than the 10-year average for the river.

The GWCT have said freshwater habitats could be managed to produce lots of large juvenile salmon with the best chance of surviving their marine journey to return to their natal river to spawn.

Recent research led by the GWCT found that warmer winters and wetter spring conditions contributed to lower numbers of juvenile salmon in numerous Welsh rivers.

Dr Stephen Gregory, a GWCT Fisheries Scientist, said: "Findings from Welsh rivers also applied to a southern English chalk stream suggests the effects of unusual weather conditions are more widespread than we first thought, and could therefore be usefully incorporated into future salmon recruitment models."

GWCT collected data on juvenile salmon collected at multiple sites throughout the River Frome catchment from 2015 to 2020.

The data revealed a combination of warm winters and cool springs had a negative influence on the numbers of juvenile salmon.

Warmer temperatures during spawning in winter could disrupt adult spawning behaviour or egg development, and cool temperatures during fry emergence in spring could reduce feeding and growth opportunities, and ultimately survival.

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