This past week, HCSEG continued a partnership with WDFW and private landowners on an exciting project! With fall chum eggs secured from George Adams Hatchery in Shelton, WA, five different Remote Site Incubator (RSI) sites were stocked with 190,000 fall chum eggs! Three RSI sites are located near Union, while another is located at Belfair Elementary School, and the last near Poulsbo.
Eggs are deemed ready for RSI when they are “eyed up,” meaning that their eyes (and vertebral column) have become visible in their egg shells. This only takes about 25 days from fertilization to occur! Even more fascinating, if you look closely at the assembly of eggs, you can see the eyes moving in some individuals! Before pick-up for RSI sites, hatchery workers move the eggs from incubation trays to tanks, in preparation for their new home in the RSIs. The eyed stage is the optimal time for transport because it is when the egg shells are strongest and least susceptible to damage from handling or being temporarily removed from water immersion. We kept our eggs wet by laying them gently onto a damp towel in plastic containers or buckets and covering them with damp burlap sacks during transport.
So, let’s talk about what an RSI is comprised of, and how it works! RSIs are used to incubate salmon from egg-to-fry in areas with variable and often poor natural spawning rates. The benefits of RSIs are that they can be used in remote settings (due to being light-weight and portable), require minimal maintenance, are inexpensive, and increase egg-to-fry survival rates in previously mentioned sites. RSIs as they are used today were developed by Washington Department of Fish and Wildlife during 1985-86. They are generally comprised of a single 55-gallon barrel that can successfully incubate over 100,000 salmon eggs at once! Stream water enters the 55- gallon barrel through an inflow pipe that attaches to a water diffuser at the bottom of the barrel. The water flows up through a filter into pea gravel covered by artificial substrate of plastic webbing and up to mesh egg trays, which are full of eggs and stacked on top of each other. Water flows through the eggs and out through an outflow pipe at the top of the barrel, back into the stream. This system utilizes upwelling water, which provides the eggs with clean, oxygenated water. The eggs are covered by a screen and a lid is secured on top of the barrel protecting young salmon and providing their required darkness. Once hatched, alevin will be able to slip through the mesh egg trays and reside temporarily in the substrate at the bottom of the barrel while they button up. As alevin button up, they absorb their yolk sac and become fry. The fry will then naturally exit the RSIs at the barrel’s top outflow pipe into the streams to begin their adult lives! Monitoring of each site will be ongoing until all fry have been released.
Working in partnership with WDFW and private landowners on the RSI program is important to HCSEG because it contributes to the fall chum population in Hood Canal. Increasing egg-to-fry survival rates on streams that would otherwise have poor spawning rates means that we are adding salmon to Hood Canal that would not otherwise survive (or even exist!) Salmon recovery affects us all, and will contribute positively to our community, economy, and watershed. It is our hope that the incubated salmon will thrive on their own and return to spawn where they were reared, contributing to each of these areas and making Hood Canal a healthier place for all!