DFG Studying King Salmon Smolts

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April 27, 2002

DFG Contact: Paul Wertz (530) 225-2362

DFG STUDYING SMOLTS

REDDING--While the background noise continues over water distribution within the arid upper Klamath River drainage, Department of Fish and Game personnel are working to improve the life of the basin’s wild and hatchery king salmon.

The DFG’s Region 1 office in Redding said a study under way at Iron Gate Hatchery northeast of Yreka is, among other things, fine tuning production methods on behalf of the 6 million Klamath king salmon the hatchery produces annually.

Fish and Game officials said the 36-year-old hatchery is going to great lengths this spring to improve survival of its newly hatched fall chinook salmon and, in turn, wild juveniles they compete with, by releasing 4.9 million two-inch hatchery “smolts” in six groups based on growth and calendar dates.

An additional 1.1 million yearling chinook are released in late fall, the DFG said.

Monitoring and data collection in conjunction with the new spring release process are at the crux of the DFG study, which itself emanated from a joint DFG-National Marine Fisheries Service preliminary examination of anadromous hatcheries and their operational relationship with the natural, or wild, stocks of fish.

Among parts of the study is a downstream measurement of the migration timing and survival rate of juvenile king salmon released from the hatchery in comparison to those that hatch in the wild. Federal agencies and Klamath tribal representatives are cooperating with the DFG in doing the downstream evaluations, Fish and Game said.

On the hatchery side of the equation, one goal is to see if changes in the normal release of the young fish result in any improvement in the percentage that grow into three- and four-year-old adults and make it back to the Klamath basin to spawn.

“We hope to improve the survival rate of Iron Gate fish by spreading out the releases over a longer period of time and by attempting to hold the salmon until they reach an optimum size for their run to the sea,” said Kim Rushton, Iron Gate manager.

The young salmon are the offspring of adult, fall-run chinook that migrate about 190 miles from the Pacific Ocean to Iron Gate each October. Eggs from the fish are incubated and hatched during the winter and the largest batch of young released in the spring.

In past years, the DFG said, the hatchery procedure called for releasing all 4.9 million smolts over a period of about three days during the first two weeks of June--depending on the river’s flow and temperature. The average weight would be about 90 fish per pound, some much larger and some much smaller.

Under the modified procedure, groups are being released over a period of a month and only when most are at or above the 90-per-pound size. The larger a smolt is during migration, the greater its chances of survival, biologists have found.

By spreading the releases over a period of approximately May 10 through June 10, biologists hope that the hatchery juveniles will not be overly competitive for food and space among themselves and will not displace or out-compete the natural smolts that often are the same age, but smaller. The releases are timed to occur after most wild juveniles are well on their way to the ocean, the DFG said.

This year, Rushton said, the hatchery released its first group of 863,000 king salmon smolts on May 10 and a second wave of 855,000 on May 21. Two more releases are set for early next week and the final one or two in early June, depending on river flows and temperatures.

In past years, the hatchery has walked a tight rope between holding the young salmon until they reach a healthy average size and releasing them before the Klamath River’s temperature reaches a dangerous level. High temperatures can induce disease outbreaks in the young fish or kill them outright, biologists say.

So far this year, river temperatures have been well inside the safe zone, Rushton said, holding at mid week around 56 degrees. Over the years, the DFG has released the hatchery salmon if the river nears 65 degrees, irrespective of the size of the juveniles.

Fish and Game said tiny coded wire tags are being injected into the noses of about 50,000 young hatchery king salmon within each release group. The tags, which tell biologists about the date and origin of a fish, will be recovered from adult salmon caught by anglers.

Rushton said Iron Gate is not making release schedule changes for either its coho salmon or steelhead smolts. The hatchery’s annual goal is to produce 75,000 coho and 200,000 steelhead.
 

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