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,
Coonamesset River while environmental awareness has increased, bringing the conservation goal to the fore. While the Coonamessett maintained a healthy herring run for many years alongside Cranberry cultivation, in recent years the herring run has undergone a massive decline, following a similar decrease across New England which has been widely attributed to at-sea factors external to the rivers. In 2004, fish counters saw only 640 fish and the only about 2000 herring returned to spawn. Concern over the herring run and the disappearance of sea run trout has led to a consensus in the Town for better protection and improvement of the