Here's a bit of data from the CT DEP taken from 1984 - 2007. It shows weight/length data detailing # of togs, the lowest weight of those togs by length class, the highest weight by length class, and the average weight by length class. Unfortunately, there is no cumulative data for anything 24" or over (just single fish).
Out of 52, 20" length class fish, the highest recorded weight was 7.4735 pounds. The lowest recorded weight for the group of 52, 20" Tautogs was 5.9965 lbs., for an average of 6.746 lbs or a variable weight for 20" class fish of 1.477 lbs. from highest to lowest weight.
On the other hand, according to the data, only 1 24" fish was involved in the study. It weighed 12.3236 lbs. Look directly below it and you'll see a 26" fish with a recorded weight of 7.3523 lbs., which is a remarkable disparity (4.9713 lbs.) in weight as to what we would think the larger fish should weigh. Also, if you check out the 22" class fish you'll notice the heaviest individual was 10.3616 lbs. and the lightest was 6.9224. A weight variable of 3.4392 lbs.
The conclusion one can glean from this data is that Tautog tend be of uniform weight among length classes, but the study also tells us that the weight of individual specimens can, and will, vary greatly from what one would expect.
What would have been more interesting would be if the girth measurements of these fish were included to compare the weight variables.