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Fish hatchery work at top speed

February 8, 2014
By Garry Brandenburg , Times-Republican

TROUT are primarily a hatchery raised critter in Iowa. The Hawkeye state does have a few brown trout naturally reproducing but the majority of rainbow, brook or brown trout are raised in carefully controlled hatchery systems. It is a specialty service that takes a big effort and special facilities and knowhow in order to bring the fish from egg stage, through fertilization, hatching and rearing. It works. And this is where some of Iowa fishing license fees are used to support the field work of hatcheries in Iowa.

The future of trout fishing sits at the present time in trays and raceways filled with cold clear water at the Manchester fish hatchery. The final spawning of rainbow trout has taken place for those fish destined for 2015 stocking. They will be carefully fed during 2014. The year class for 2014 stocking however was at this stage last year. It takes time to allow sufficient growth to occur.

Tiny brook trout and brown trout move within clusters similar to a dark cloud within the raceway water. Every 20 minutes, a timer dispenses a special commercial trout food. The fish have learned that supper is served. Rainbows are now in the sac fry stage, newly hatched but still obviously heavy with the yolk sac that gave rise to their life. A constant flow of cold clear water passes over them from springs within the nearby bedrock. The Manchester hatchery has been operating since the late 1800s due entirely to its volume and quality of fresh water. Prior to Iowa DNR using the facility, it was a federal fish hatchery.

Article Photos

CONTRIBUTED PHOTO
Rainbow trout are one of the species hatched and being raised this winter at the DNR ‘s Manchester facility. Approximately 350,000 rainbow trout will be grown to catchable sizes before spring arrives. Rainbows were one of the trout species released into Sand Lake last year. The cold water should still hold some of these fine fish.

Rainbow trout see an annual total of 300,000 to 350,000 fish raised. Brook trout come in at 50,000 to 75,000. Brown trout raised number between 125,000 and 175,000 and at the two inch stage are ready for May delivery to streams where natural reproduction does not happen. Brown trout stockings supplement about one-half of the spring fed trout stream watersheds of northeast Iowa.

Hatchery spawning begins in October through January. Since this is February, the shift in hatchery work involves feeding the litter critters. The last of the big 6 to 8 pound brood females are stripped by hand as workers gently but firmly rub bellies to steer streams of bright orange eggs up to 4,000 to 6,000 per fish into a net and then into a plastic bowl. With similar motion, sperm is extracted from brood males and mixed into the egg mass. The mix is stirred for 30 seconds with a turkey feather. Why? Because the gentle motion of the feather does not harm the delicate eggs and is proven to allow for 95 to 99 percent fertilization rates. This is dozens of times greater success than what happens naturally in the wild trout streams.

For junior and senior University of Northern Iowa biology students or education majors, a field trip to the hatchery is a wonderful hands on experience. They put on a raincoat and elbow length rubber gloves to hold the brood fish and coax egg streams into the net. For the unit of study on fish, experience at the hatchery is a great learning tool says UNI Dr. James W. Demastes for his Field Zoology class. Hatchery technician Randy Mack watches over the dozen or so students learning the ropes of fish work.

Fertilized fish eggs go into trays, then into incubators units for 30 to 45 days, depending upon water temperature. Once hatched, it takes another four to five months indoors before the fish are moved to outdoor raceways at either the Decorah or Elkader rearing stations. It takes a total of about 1.5 years to bring a trout to the eleven inch mark or about half-pound. This is a desired catchable fish. The public needs to remember that trout stocked during 2014 were raised in 2013. That is what it takes time wise to do the job.

Iowa trout fishermen/women go fishing for browns, brooks and rainbows each year. That number has grown in part due to the expansion of Iowa's cold weather urban trout program. These trout can endure through the winter in 17 small lakes, ponds and renovated quarries throughout the state. Sand Lake is one of the 17. And this scribe salutes the DNR workers at all levels that make fishing for trout a task well worth the effort. Please join me in this pat-on-the-back for a job well done, and a job continued to be diligently followed.

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Our very low and slow running IOWA RIVER is chugging along at a snails pace typical of mid-winter. The snow pack is small but cold weather has locked it up tight. Feeder streams are also locked up. All will change when a several day long thaw does come to pass, the snow melts, and runoff enters streams and the river. As for now the river is flowing unseen under the icy lid of frozen surface water. It's volume of flow is approximately 380 cubic feet per second. That is tiny but typical. To illustrate how the river can change, it was on May 30, 2013 that the crest was noted at 22.08 feet and a flow rate of 23,695 cubic feet per second!

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BALD EAGLES and eagle watching was noted in last week's Outdoors Today story. The question was asked of me how many eagles Iowa hosts during the winter. The answer is hard to pin down precisely since the Missouri River and the Mississippi take the lion's share of over wintering eagles. The small zone of the Mississippi from Fort Madison to Keokuk has at least 2,300 eagles. Extrapolate those numbers all the way to Lansing in northeast Iowa and you will have a really big number, well over 10,000. Then the rest of the state has to be added. I'd speculate (guess) that within Iowa's borders there are at least 15,000 eagles. That is a lot of birds of prey. Locally I have a recent report of one new eagle nest not too far from Le Grand. It was built in 2013. For whatever reason, the old nest that had worked was vacated during 2013. The new nest will be added to during 2014 for sure. The mated pair of eagles is likely to be setting up shop very soon, getting ready to lay a new clutch of one, two or three eggs. The incubation period timing will be just in time for the end of winter beginning of spring. Open water in the river will expose new food sources and fish returning upstream from wintering areas as far away as Coralville reservoir.

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Feb. 2 was GROUND HOG DAY. Old Mr. Woodchuck in Iowa was found sleeping. Good for him. Our weather of late has been not fit for man or beast. People have been 'hibernating' in effect by adapting to severe periods of cold arctic air. It is amazing how a slight track change in the jet stream pathway can allow the severe arctic cold to penetrate all the way to Florida. Holy catfish Batman, that is a lot of cold air. Meanwhile in Anchorage, Alaska, the residents are wearing shorts in 40 degree weather. Go figure.

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My thought for the day is this: If vegetarians eat only vegetables, what do humanitarians eat?

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Garry Brandenburg is a graduate of Iowa State University with BS degree in Fish & Wildlife Biology. He is the retired director of the Marshall County Conservation Board. Contact him at PO Box 96, Albion, IA 50005.

 
 

 

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