What a fish! A 45 inch steelhead is a true monster and one with that kind of girth would weigh in the mid-30s. That said a similarly built fish would have to be at least 47 inches long to have a chance to reach that magically 40# mark
With at least our winter steelhead those true giants are nearly always first time spawners. One in the Sauk winter brood stock program there were 3 seven year old fish. One was a male that went to sea as a 3 year smolt returned to spawn as a 2-salt and was returning to spawn for the 3rd time. It weighted 16.5#. Another was a female that went to sea as a 2 year smolt returned the first time as a 3-salt and always so returning for the 3rd time and it weighted 22#. The third was also went to sea as a 2 year smolt and was returning for the first time and weighted 32#. Typically the fish during after its time in the river and the rigors of spawning typically lose so much weight it takes much of the falling year to recovery and maybe grow a bit.