In fisheries science terms that BG is age 2 (barley). Common sense dictates another approach. I find it much more useful here to put small fish ages in terms of months as near as possible. That is because of the variation in spawn times that hatcheries have. In the deep south you may see a hatchery with 3 or 4 distinct yoy age groups of BG or more in one spawn season. On Dec 31/Jan 1 a hatchery may have 1 , 2 , 3 , 4 and 5 in. yoy/age 1-2 BG (actually anywhere from 2 to 9 mths old) . Mike's are probably 17 mths +- .