Atlantic salmon regenerate damaged gill tissue through three distinct molecular phases spanning at least 20 weeks, according to a new study that could help researchers better understand recovery from gill disease and physical injury.
The research found an initial inflammatory and tissue-repair phase lasting up to four weeks, followed by a period of tissue outgrowth and structural development between weeks four and 12. A final consolidation phase extended to week 20, as regenerating tissue recovered functions linked to ion regulation and neural activity.
Researchers tracked gene expression in juvenile Atlantic salmon after surgically removing 50% of selected gill filaments. More than 2,500 genes were differentially expressed during the first week following injury, highlighting the scale of the biological response.
After 20 weeks, the damaged filaments had recovered approximately 38% of their original length, although the fish showed substantial recovery of respiratory and ion-regulatory capacity.
The study also found that successful regeneration was associated with a faster transition away from inflammatory and proliferative states towards differentiated tissue development, suggesting that prolonged repair responses may hinder recovery.
The findings were reported in Transcriptional regulation of gill regeneration and functional recovery after resection in Atlantic salmon (Salmo salar) by researchers from the University of Stirling, the University of British Columbia, Memorial University of Newfoundland and the Atlantic Veterinary College.
The authors said the work provides a molecular framework for understanding gill repair and could help guide future strategies to support gill health and fish robustness in aquaculture.
