Good questions FishingRod.
Those are all Fall metrics. There are no Spring pre-spawn metrics in their report.
Good observation on the early going being essentially equal. RW was a coin flip as an indicator of sex during the first 5 years (really throughout the study there is no statistical support of RW as an indicator of sex). The reason for the divergence of males late in the study deals with the benefit of being smaller than females. IOWs it takes less forage for a smaller male to put on excess weight (weight above 100 RW) than it does a larger female.
Immediately pre-spawn, lady LMB should be at their highest RW.
I don't think this is necessarily true. For the RW to be higher, the lady LMB must gain weight and this means she must consume enough forage to support her current fall weight and additional to forage for gain. There will be, of course, cases where this takes place but there will also be cases where she is only maintained or even cases where she loses weight through that period. It depends soley on how much she consumes. She may gain length which would be a headwind against RW. In any of the above cases she will grow eggs and the eggs in the spring will be a greater proportion of her body weight than they were in the Fall. In cases where she doesn't gain weight, there will be a transformation of muscle and fat into egg mass. So the pre-spawn ladies have more distended bellies but not necessarily higher RW.
But for sake of discussion. Let's consider the cases where female LMB are of higher RW prior to spawning. In these cases we know the females consumed a surplus of forage over maintenance. But if this is true and conditions prevail that support additional weight gain from Fall to Spawn, wouldn't the conditions also help male LMB gain and improve their RW? Should we presume that it is easier for Females to gain RW than males? For example, is the larger proportionate mass of eggs less energy dense than the male's smaller (by proportion) mass of male gametes? It is really hard to argue that males are at a disadvantage for over winter increase of RW. There is no spring data in their report so it is an unknown for their study.
So one thing I had always previously thought. "Males and Females may have separate Standard Weight Functions". But this seems to be completely debunked by their data. For the first five years there was little difference of RW between the sexes using the same standard weight function. It seems hardly worth the effort to model different standard weight functions for each sex.
