A 4-5 in BG from last fall would be capable of spawning this summer (it would be a year old) unless it was suppressed by one or more factors such as lack of spawning areas or many larger male BG or poor condition due to lack of food.
WRT the BG stocked 6 mths earlier what size were those BG when they were stocked? If they were 2in when stocked then they are all the same year class. BG grow quickly , mature and grow old in a hurry down here. A 5 year old BG is old in a southern location while it is just reaching its prime up north. From a 2006 study :
Differences in Population Metrics between Bluegill and Redear
Sunfish: Implications for the Effectiveness of Harvest Restrictions
STEVE M. SAMMONS*
Department of Fisheries, Auburn University, 203 Swingle Hall, Auburn, Alabama 36849, USA
DAVID G. PARTRIDGE
Georgia Department of Natural Resources, 109 Hatchery Access Road, Dawson, Georgia 39842, USA
MICHAEL J. MACEINA
Department of Fisheries, Auburn University, 203 Swingle Hall, Auburn, Alabama 36849, USA
North American Journal of Fisheries Management 26:777–787, 2006
Copyright by the American Fisheries Society 2006
DOI: 10.1577/M05-159.1
Many studies from northern systems have collected
bluegills as old as age 10–12 (Goedde and Coble 1981;
Otis et al. 1998; Schneider 1999); however, we rarely
collected bluegills older than age 5 in our reservoirs.
Ott et al. (2003) found few bluegills older than age 2 in
a Texas impoundment and attributed this to fast growth
rates and associated high mortality rates. Bluegill
harvest was assumed to be moderate because only 10–
12% of annual effort was directed at bluegills (Ott et al.
2003). However, Belk and Hales (1993) found bluegills
as old as age 9 in a South Carolina power plant
cooling lake where no fishing was allowed, so angling
may affect longevity of bluegills, even at moderate
rates of exploitation (Goedde and Coble 1981). In
contrast to bluegills, redear sunfish older than age 5
were common in our study reservoirs, and fish as old as
age 9 were collected in each reservoir.
Fish longevity has been linked to natural mortality
rates (Hoenig 1983), and the estimated natural
mortality of bluegills was generally greater than that
of redear sunfish in all three reservoirs.