Rob is correct the male bass selects the bedding site, constructs the bed, escort the female to the site. After the eggs are laid the male guards the nest and in the case of the largemouth guards the resulting fry for a week or 10 days.
It is not uncommon to the see a male to select the same nesting site year after years. And yes, in largemouth populations the male is smaller (at times much smaller). During the 1980s I had the opportunity to fish a couple clear water lakes with expanding smallmouth populations. During the early years the males and females were similar sized; in some cases I could watch the spawning of a pair where the males and females were sized size (often with both in excess of 5#s). As fishing pressure increased, especially the practice of bed fishing in a few years the size difference between the sexes increased. While it was still common to see 4 and 5 (or larger females) in became rare to see males in excess of 3#. The aggressive nature of the nest guarding males resulting in some of those fish being caught multiple times (some of the fish's mouths looked like pin cushions with 10 or more hook wounds) during the spawning season.
Curt
