The phrase "trout populations" refers to the number and grouping of trout in a specific area, such as a river or lake. It describes the quantity and distribution of these fish. Full definition
Are brown trout replacing or displacing bull trout populations in a changing climate? (montanaclimate.org)
Owing to this morphological similarity, westslope cutthroat trout populations with less than 20 per cent non-native admixture have been included as part of the native taxon in a recent status review (Department of the Interior (DOI) 2003). (rsbl.royalsocietypublishing.org)
The native bull trout population is exploding, with more nests and some of the highest spawning counts on record. (discovermagazine.com)