Wednesday, May 9, 2012

Outta Here!

Springtime is busy at the Dworshak Hatchery.  The smolts have left via truck and forced release into the Clearwater river and its tributaries.  They will ride the spring freshet (high water) down the Clearwater river and into the Snake River system.  Once in the Snake, they will first encounter Lower Granite Dam.  Many of the smolts will be trapped in the smolt bypass system and loaded onto barges for the remaining trip down the Snake and Columbia Rivers.  Some of the smolts are PIT tagged and released back into the hydro system to evaluate the effects of barging.
Crowded steelhead smolts await release

On the Hatchery, releasing fish is a one to two week process in early April.  Chinook salmon smolts are generally released onsite, called “direct release”, into the North Fork Clearwater River.  The fish are forced out of the raceways with crowding screens rather than volitionally released (leave on their own accord).  This process generally takes one to two days.  The hatchery crew releases the smolts in the evening hours when the light levels are low and the seagulls are less apt to spot the young fish.  This strategy gives the young fish the cover of darkness to disperse from the hatchery and avoid initial predation.
Crowding steelhead smolts to the release channel
Steelhead smolts "direct released" to the Clearwater River

About half, 1.2 million, of Dworshak’s steelhead smolts are direct released into the Clearwater river.  The steelhead smolts are significantly bigger than the Chinook salmon smolts (8 inches versus 5 inches), and suffer less bird predation.  The direct release smolts are also forced out with crowders, but are allowed to volitionally release from the transfer channels.  Most of the steelhead swim out quickly, within 1 to 2 days after being forced from the Burrows Ponds.
Getting ready to pump steelhead onto on "off-site" release truck
The remaining steelhead smolts, 1 million, are transported by semi-tanker trucks to offsite release areas in the South Fork of the Clearwater River.  These releases provide fisheries and restoration benefits in the upper reaches of the South Fork.  The smolts are sucked onto the trucks with large fish pumps.  These pumps are specially designed not to damage the young fish when they traverse through the pump impeller.  Once in the transport tanks, the smolts are provided with oxygen and aeration for their trip to the release sites.  The transport times vary between 1 to 2 hours.  Once at the release sites, the fish are released through a large release tube – much like a waterslide for fish!
Releasing steelhead smolts from the transport truck

by Nate Wiese

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