Consider that hatcheries need an ample supply of fingerlings almost year-round. To get larger fingerlings quicker we stock low numbers/acre. If we stock high numbers we maximize production capability in terms of numbers, which can later be spread out for a phase 2 or phase 3 production. Since fingerlings are sold by the head, why limit efficiency by stocking low numbers just to get fast growth. The hatchery still needs to make certain profit/acre of water.
For catfish, bluegill, and bass fingerlings purchased from a reseller in the fall, odds are fair that they are this year's fish. For fish purchased in the spring, these fish of same size are most certainly almost 1 year old.
There are benefits. 1 year old bluegill, even 1"-3" fish can spawn soon after stocking in the spring. Catfish fingerlings that are "held back" can grow faster and be more resistant to disease than new fingerlings.
Certainly do not stock bass fingerlings, I mean 2"-4" fish in the spring as they've lost a year of potential growth and that may affect maximum growth potential. The same is true when you buy adult bass, you have no way of knowing how old that fish is. It may be 4 years old and only weight 1lb. To grow trophy bass, make sure to stock new fingerlings, 2" fish in late may/early june is about right.
As for HSB fingerlings purchased in winter/spring, I am very serious about this, I doubt that their growth rate is affected unless they aren't on feed. All you sacrafice when buying HSB in spring is time that those fish could have been growing in your pond, which will definately affect maximum growth potential as these fish have relatively short lives.
Stunting is not a permanent condition or disease, just a condition too much competition, too little space, and/or too little food. Once stunted fish are stocked out they exhibit similar growth as natural stocks, but they have lost max growth potential.
All the fish on our farm are this year's fish, except some F1 bass and some coppernose that we are growing to adults.
I have been a "reseller" in the past and still buy some fish. Efforts of some farms to maintain a year-round supply of fingerlings is as much of an art as it is a science.
