Outdoor Alaska: Alevins hatching at Trail Lakes Hatchery
It's been four months since the staff at Trail Lakes Hatchery collected eggs and milt from sockeye returning to spawn at Hidden Lake on the Kenai Peninsula, and now those eggs are beginning to hatch.
The hatchery's method for the Hidden Lake fish is to incubate and release unfed fry.
"It's unique because instead of taking the fish and rearing them on the hatchery, we actually stock them out when their yolk is fully absorbed and they're ready to go out and eat and be fish on their own. They never actually live in the hatchery raceways," Trail Lakes Hatchery Manager Brett Jenkins said.
Hatchery strategies with as little involvement as unfed fry don't work well everywhere, but in cases such as Hidden Lake where the technique is effective it can be desirable over other techniques. Not only does less time at the hatchery cost less, but it's closer to the natural process.
"Hidden Lake is a very productive system, and they just do well. We're able to stock them out as fry and they perform well. They don't necessarily need that time on the hatchery to survive and return, and I think it's a desirable technique when it's possible," Jenkins said. "These fish have to go out and forage and find food on their own and survive like a natural fish would, instead of being fed in a hatchery."
The fry will be stocked around May after ice is off the lakes and there is plankton for them to eat.
The eggs have already been thermally marked to imprint a specific pattern on their otolith, or ear stone. The marking will allow every fish from this group to be traced back to the Trail Lakes and this specific group.
"We capture these fish when they're out-migrating from the lake, either at 1 or 2-years-old, and we can tell which percentage of our fish survived to that age. We can tell what percentage of the out migrating fish were hatchery origin versus natural origin, and we'll use those otoliths again on the returning adults," Jenkins said.