When talking to anglers, fisheries biologists are often asked, "How fast do bass grow?" This is particularly true for big fish. An angler who catches a big bass wants to know, "How old is it?"
Fish can be aged by examining scales or various bones. Hard body parts grow as the fish grows, adding annual rings similar to the rings in trees. Because the growth in the diameter of the hard body parts is proportional to the growth in length of the fish, examination of these structures reveals not only the age of the fish but also its length at each birthday.
By examining a sample of bass, information can be obtained about the growth history of a lake’s bass population. Alabama Wildlife and Freshwater Fisheries Division biologists collect this type of information on a regular basis. Most of the fish examined are five years old or younger, but we have seen a few largemouth bass as old as 16.
Growth can vary greatly between individuals. Without examining scales or bones it is not possible to say exactly how old a particular fish might be, even within a single population. Growth is dependent on the abundance of the right size forage and its availability. Food availability varies seasonally, annually, between reservoirs, and even between locations within reservoirs. Knowing this, it is possible to make some general observations about bass growth. The following table shows the average growth of largemouth bass and spotted bass in Alabama reservoirs.