When NJ Angler did their Delaware River Shad show they mentioned that both shad and herring numbers were significantly lower in the river in the last few years than in any of the years past. From what they said, herring and shad follow similar spawning patterns and always return to the same River where they "hatched." The lower numbers don't mean that the population is in trouble, but that the fish that were born there are not returning or turned into fish bait somewhere else
. This can be very normal and tends to be cyclical at times. Maybe, this is just not a good herring year??