Rahway River migrations. Fish ladders are inundated structures with small underwater steps that allow fish to navigate around a dam and continue their migration. Other approaches include removing obstructions that are inoperative or no longer serve their purpose, or improving water quality and reducing debris that obstructs passage. The fish targeted for upstream passage at the Rahway River Water Supply Dam are alewife (Alosa pseudoharengus), blueback herring (Alosa aestivalis), gizzard shad (Dorosoma cepedianum), white perch (Morone Americana) and the endangered American eel (Anguilla rostrate). Alewife and blueback herring are collectively referred to as river herring due to their similarity in appearance, range,
Herring scad shallow coastal regions where it inhabits the surface layers of the ocean over a variety of substrates. The herring scad is a carnivorous species, known to consume a variety of crustaceans including shrimps, copepods and decapods as well as other small fishes. It is one of a number of pelagic fish from the Red Sea found to have high numbers of luminescent bacteria in its gut, living symbiotically with the fish as part of the gut flora. Parasites of the herring scad include the philometrid nematode "Philometra austropacifica", which lives inside the ovary of the females. The species is of