actinopterygii alabama shad alewife allis shad alosa caspia alosa maeotica alosa vistonica american shad animal atlantic ocean atlantic salmon biological classification black sea carboniferous caspian sea clupeidae clupeiformes cretaceous devonian digital object identifier eocene evolve fish fish migration genus habitat herring hickory shad ireland john mcphee jurassic killarney mediterranean sea ordovician paraphyly permian persian gulf pollution roe salmon shad planking silurian skipjack shad subgenus triassic ultrasound vinegar virginia