Time of year can easily be a factor as you noted. LMB are heaviest pre-spawn (March+-). They lose weight during the spawn and gradually gain weight over summer and fall. Depending on location they can lose some weight over winter.

Use length and weight and the standard RW chart. Knowing if the RW ( 86%) was consistent over all size classes would be a good fact to develop. If one size is more under weight than others it indicates a food shortage for that size and thus potential stunting.

My guess is that you are a little LMB crowded . I would suggest that pending a survey and better data across all sizes that you cull some small LMB and all crappie . Take out LMB at a rate of no more than 20 lbs per acre of LMB 8 to 12 inches.