Norwegian Research Centre Norce and volunteers have recently been busy hunting down farmed salmon from rivers following a major escape from Danish feed company Aller Aqua.

A total of 35,000 salmon escaped from Aller Aqua's breeding facility in western Norway on Oct. 29.

Aller Aqua confirmed a small number of the escaped fish were ready to spawn, estimating around 1 percent of the males carried milt, or sperm.

Sexually mature farmed salmon can travel up rivers and reproduce or displace wild salmon.