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from what little reading i've done on menhaden:
large bunker migrate up and down the coast during the year, combined with inshore to offshore migrations within that migration. the largest concentration of bunker at any one time occures off the coast of the carolinas in the winter, which is where most of their spawning occures. in early spring, they migrate both south to florida and north to nova scotia, with the larger ones typically going north (no clue why). as they migrate, they spawn more throughout the year, with spawining occuring closer to shore the further north they move, until spawning actually occures within tidal rivers and backwaters as it does up here. i assume this is based on providing the most favorable conditions for the spawn. the fish spawned up here live in the rivers and backwaters until fall when they begin dropping out and moving south.
seeing that the population of adult bunker is on the rise here, i would suspect that the lack of peanuts could be based on conditions in the spring (heavy rains, strong currents, heavy winds, you name it). maybe they just choose not to spawn up here some years based on a set of conditions no being met. or they spawn, but conditions are not optimal for their survival and only small numbers survive.
since the majority of spawning occures down south in the winter, i would not think that fluctuations in when and where the more minor spawning events happen would have little effect on future populations, unless something needs to be considered based on regional survival rates that i don't know enough about to comment on (ex. maybe the fish born off the carolina are more susceptable to seining?)
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