Rainbow Smelt in the Parker River
This information was provided by the Parker River Basin Team
Late in the month of March and into April, rainbow smelt (Osmerus mordax) arrive from the estuary to their spawning sites in the mainstem of the Parker River and a few of its tributaries. Jerome et. Al. (1968) reported smelt actively spawning at five separate locations in the basin. These areas were located at the Central St. Bridge in Newbury; Cart Creek, Newbury; Glen Mills on the Mill River in Rowley; Rowley Town Brook, Rowley; and Egypt river in Ipswich. Spawning takes place at night in fast moving shallow waters over clean hard substrate. The sticky eggs rapidly sink and adhere to aquatic vegetation and/or clean substrate. After hatching larvel smelt are passively transported downstream by the river flow.
Smelt populations have fluctuated greatly through the years in the Park River system as is true for most New England coastal runs. However, since the mid-1970s, smelt numbers in the Parker River system have been declining annually. A field study conducted by the Mass. Division of Marine Fisheries in 1991-1992 found low numbers of smelt spawning at only two sites, Central St. and Glen Mills. Despite looking at a variety of physical, chemical and biological parameters, a single cause could not be identified to explain the apparent decline in the smelt population.