STOCKING PA LAKES AND STREAMS.... the what for's

Following is an excerpt from a report issued by the PFBC regarding the stocking of Penn's Woods lakes an streams.  Listed at the end is a link to the full article.   I found the report interestiiiii 
 
 
"The period of time necessary for warmwater and coolwater fishes to attain desirable size or legal size typically spans several years (3 to 4 years depending upon the species). Consequently it would be extremely inefficient and very time consuming to attempt to rear these fish to adult size. Most studies show that warmwater and coolwater fish grow faster in the wild as opposed to in a culture setting so it might take even longer for cultured fish to attain adult size. Stocking juveniles into natural, albeit altered habitats leads to the greatest gains in growth. As might be expected, fish stocked as juveniles endure the rigors of life in the wild (ex. predation) much as their wild produced counterparts, and all do not survive. The Pennsylvania Fish and Boat Commission has evaluated survival of a variety of sizes (life stages) stocked at a variety of times, at a variety of density levels, in a variety of water bodies and uses data from these evaluations to guide rearing and stocking procedures such that survival and resulting population levels are maximized. The number of warmwater and coolwater fishes reared and stocked is very large, much larger than the number of adults that would be stocked. Since smaller size fish require much less rearing space, the Fish and Boat Commission can rear very large numbers of a wide variety of warmwater and cool waters fish for stocking in numerous waters.
For a given water body numbers and species of fish to be stocked are very carefully defined. After a biologist (Area Fishery Manager) samples or inventories the water body and carefully evaluates fish abundance and condition, including forage fish abundance, a Fishery Management plan is developed which details the species and life-stage of fish to stock as well as the regulation (harvest) program to be applied to the water body.
Some fish are stocked as fry just a few days old; others are stocked as fingerlings and are several months to many months old. The rearing duration of a fingerling is (1) frequently a function of timing release such that forage organisms are abundantly available in the receiving water (for example if it is known that a particular minnow species or forage species produces an abundance of young in June, fingerlings of a size capable of consuming those young are released at that time), (2) a function of the size defined by Area fishery managers for stocking to avoid predation, and/or, (3) a function of the availability of natural food resources in a rearing pond, regularly checked by fish culturists. On rare occasions small numbers of adult size warmwater and coolwater fishes are stocked in association with re-establishing fish populations in newly constructed or newly re-filled reservoirs. Here the adult fishes are stocked as brood fish that will produce numerous young, and not stocked to be caught as adults by anglers although some capture occurs. Combinations of adult and young fish in an initial stocking can affect the ultimate size structure of adult fishes some years after stocking, great care is exercised in stocking adults in combination with juveniles. For example adult size largemouth bass are stocked in combination with fingerling bluegill to produce a balanced size structure. To simplify it has been shown that this combination yields sizes of bass and panfish that are desirable by anglers without one species predominating or small size fish of either species predominating."`~ PFBC
 
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