Lets start with length weight comparison. You begin by taking the length and weight collected for each fish caught and chart it in a scatter plot. This will show you the actual weight of each fish at its given length. I then prefer to add a line in the graph to show standard weight. To do this you must first determine the standard weight of each bass caught. This can be done using a formula (10^ (-3.49 + 3.191 * Log10 (L))) or more commonly by using a standard weight chart. Standard weight charts and formulas for many fish species are available below. The standard weight of a fish is the weight it should weigh based on its length. The standard weight relies on the fact that fish do not have an age determined length, instead their growth is dictated by consuming food. Once you add the standard weight line into your graph you would then look at how close the fish that were caught are to the standard weight line. In our example the fish are grouped very tightly but slightly below the standard weight line. This means that the majority of the population is slightly underweight however is not grossly underweight. How we would proceed with our management would be dictated by the past management practices implemented and the results. This weight comparison does not take into account seasonal changes in weight due to spawning activities, weather, or forage abundance.
This is when it becomes extremely important to not only keep this data for one year but instead to keep the data for multiple years so that you can go back and compare the charts, fish growth, culling activities, and everything else that is going on in the fishery. That is when you truly begin managing your pond and making wise decisions.
Thanks for reading and Happy Fishing!!
Steven Bardin M.S.