Friday, March 15, 2013

Keeping Pulse with the Seasons

You may not think that a hatchery is a place that moves with the seasons. Especially a place like Dworshak, the asphalt, concrete, and steel don’t conger thoughts of natural processes. By design a hatchery is built to keep fish in and keep their natural predators out.  But when you look beyond the man-made ponds and the bird-netted enclosures, when you look at the fish that are reared here, you can see there is a rhythm that is followed. Winter, spring, summer, and fall all hold specific milestones for each brood of fish reared here. 


Chinook Alevin
Like the stillness after a snowfall, winter is a time of calm and preparation at the hatchery. Chinook eggs hatch and alevin quietly develop in the darkness of the incubators. Juvenile Chinook and Steelhead feedings decrease as the water temperature drops and days shorten.  Hatchery staff use the winter months to prepare the nursery for the busy spring by completing annual maintenance and preparing the 128 tanks for steelhead fry arriving in March. Winter is also the time that staff PIT tag our juvenile steelhead, Coho, and Chinook. Of course steelhead spawning begins in winter but is also one of the signals that spring is on its way.


Out-planting steelhead smolts
As the days lengthen and the osprey arrive the pulse of the hatchery begins to pick up. Our Juvenile fish are smolting, ready to make the journey to the great Pacific. Their release is timed as the spring rains, and snow run off raise the water in the Clearwater River. Almost simultaneously the Chinook fry are ready to be ponded. It’s a mad dash to clean, upgrade, and prepare the raceways for the hungry fry. The steelhead eggs that were spawned in the winter are eyed up and ready to be moved into the nursery. Earlier takes have hatched and are ready to start feeding. Like busy bees tending a hive, hatchery staff feed the baby fish 8 times a day, 7 days a week. There is a lot of spring cleaning going on too. Because of all the feed, nursery tanks require daily cleaning. Chinook raceways are cleaned at least three times a week. All the empty Burrows Ponds need to be cleaned and disinfected before the next brood of steelhead can be ponded outside. As spring transitions to summer the Kings of the Clearwater, the Spring Chinook, make their first appearance.


Splitting Steelhead
Opening the fish ladder
Now the sun is high in the sky. The days are long and hot; we are all wishing that the Dworshak asphalt was lawn and the Burrow’s ponds were swimming pools. The fish ladder is opened for the first time since March. We begin trapping Adult Chinook and preparing the incubators for their progeny. The steelhead and Chinook that were ponded in the spring are growing like gangbusters and are beginning to outgrow their homes. Summer is when fish in the nursery are moved outside. The tagging crew is here marking fingerlings as hatchery fish by the removal of their adipose fin. The fish grow even more. They outgrow their homes again! Now the crew splits fish from one Burrows pond or raceway into three. The transferring, marking, growing and splitting continue into fall. 


Chinook Spawning
The pace is beginning to slow, a little. There are Chinook and Coho to be spawned though. We spawn Chinook in September and Coho in October. We keep the eggs on chilled water to make sure they develop in tune with their natural cycle. The eggs will slowly and quietly develop through the fall hatching as fall rolls into winter. Things truly begin to slow down. The fish that are outside aren’t eating quite as much. The nursery is empty. The daily feeding and cleaning schedule lightens. Demand feeders for steelhead come out. The osprey leave, the eagles arrive. Was that a snowflake?

Photos and text by: Angela Feldmann 

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