Fish First obtains over 800,000 fertilized eggs taken from late-run native stocks in the North Fork of the Lewis River. The eggs are "eyed," meaning that they have reached the developmental stage at which the embryo's eye is visible and the egg itself is durable and unlikely to rupture with handling.

Fish First puts the eyed eggs into remote site incubators, or RSIs, located in small tributaries of the North Fork that have depleted or weak native stocks.

The RSI is a 55-gallon plastic drum positioned near the stream, with PVC piping that runs stream water into the drum at the bottom, out the drum near the top and back into the stream.

The coho eggs are placed in a plastic pan with a netted bottom that sits near the top of the drum, so that they are constantly bathed in fresh, oxygenated water. The eggs hatch into alevins--tiny salmon with their egg sack still attached. The newly hatched alevin takes refuge in the gravel substrate at the bottom of the RSI, where it lives off the nutrients in its egg sack.

Once its egg sack has been absorbed, the hungry fish (now called a frye) swims out of the RSI's exit piping into the adjoining pool, where it forages for food, learns to evade predators, and rears for a year or more before smolting and beginning its migration to the ocean.

These frye imprint to the riffle next to the RSI. When these fish return as adults, they will return to that stretch to spawn. This allows the fish runs in the North Fork to rebuild over time.