Streamside and Instream Incubation
Starting several years ago the Maine Atlantic Salmon Commission’s Sidney office began evaluating alternative stocking methods for early salmon life stages using streamside and instream incubators. Eggs are incubated next to or in the stream where the product will be stocked. Hatcheries serve as an egg source only.
During the winter of 2002 – 2003, ASC tested streamside incubation with flow-through systems constructed from discarded refrigerators. Three incubators held egg filled Whitlock-Vibert boxes and three held eggs between layers of poultry nesting material. Incubators were set up prior to receiving eggs at three sites on two tributaries to the Sandy River. Hatching success average of 90% for six incubators that received 43,496 eyed Atlantic salmon eggs in February. In the fall of 2004 we began a test of in-stream incubators for Atlantic salmon eggs. Atlantic Salmon Commission staff built twelve incubators consisting of baskets containing eight egg trays. The baskets (two per site) were buried in spawning gravel at three sites on the Sandy River and at three sites on the Sheepscot River in early fall. In mid November, half of the trays were filled with eggs immediately after fertilization and water hardening. The eggs were then delivered to each of six sites and placed into the previously buried baskets. The remaining trays in the baskets will be filled with eyed eggs in February 2005.
If hatching success is consistently high for either method, the minimal time expended, and low cost makes them feasible alternative stocking approaches. Further, staff are working with the U.S. Fish and Wildlife Service on the Sheepscot River to compare the survival and growth of fry from these systems with fry stocked from Craig Brook Hatchery.