Dedicated To The Tribal Aquaculture Program

December 2001-Volume 38

TopicsOf Interest:

Aquatic Plant Control

2000Tribal Fish Hatchery Production

WalleyeSpawning Operations at Bonny Reservoir

HatcheryTips

Aquatic Plant Control(A Power Point Presentation)
By:  Gregg Raisanen, AlexandriaTechnical College, 320-762-4618 

(Please click on the images below to view each picture).

Conclusion

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2000Tribal Fish Hatchery Production
Data submitted by the Bureauof Indian Affairs (Midwest Region).  Table generated by the GreatLakes Indian Fish and Wildlife Commission.

Fish hatcheries play an important role in co-managing interjurisdictionalfishery resources. Midwestern tribes have responded to the modern day challengesof multijurisdictional resource management in their unique role as users andmanagers on over 900,000 acres of reservation inland lakes, treaty cededterritories and the Great Lakes. There are currently fifteen tribal fishhatcheries and or rearing components in the 1999 Midwest Region. Red Lake andLac du Flambeau are the oldest, being established in 1929 and 1936,respectively.  These reservations in serving tribal subsistence andcommercial needs are also contributing significant fish stocks to reservationwaters fished by over 95% non-Indian anglers.  The U.S. Fish and WildlifeService and state Departments of Natural Resources also play an active role instocking fish as a management tool in reservation waters.

2000 Tribal Hatchery Fish Stocking By Species

Walleye Spawning Operations at Bonny Reservoir, Colorado
By:  Charles O. Benneft and James L. Melby~ Colorado Division of Wildlife, 2126 N. Weber, Colorado Springs, Colorado 80907

Bonny Reservoir is a 1,924-acre plains reservoir constructed and operated bythe United States Bureau of Reclamation. The ColoradoDivision of Wildlife and ColoradoDivision of Parks and Outdoor Recreation own the conservation pool andmanage fish, wildlife, and recreation. It is located on the South Fork of theRepublican River in Yuma County, northeast of Burlington, Colorado. Walleye spawning at Bonny historically starts on or about March 20. Thirty to 45million walleye eggs are collected annually from wild captured broodfish.Average hatching rate is 65-75 %.

A two-slip boat house in a protected cove adjacent to the dam is modified forwalleye spawning. A floor is constructed over one boat slip that contains four,4 x 4 x 4 ft x 1 in mesh holding nets, a 100-gal holding tank for receivingbroodfish, a spawning table, and an oblong shallow (50 gal) tank for floatingegg boxes during the egg hardening process. A submersible electric pump provideswater for all phases of the spawning process. Overhead PVC pipes and valvesdeliver water where needed.

Standard neutral buoyancy 2.5 inch bar mesh gillnets, 6x200 ft are used tocapture brood size walleye. Nets are deployed daily at sunset parallel to thedam riprap and in sand/rack rubble shoreline areas. Net placement is in 3-6 ftdeep of water. Gill nets are checked at 7am by a boat crew of 3-5 people. Twocrew members pull the nets while 1-2 personnel remove broodfish. The sex of anetted fish is noted before removing, because removal techniques are differentdue to average size and body shape differences between sexes. Males are usuallyremoved from the nets head first, while females are backed out of the net tominimize egg loss. Standard net picks are used and additional care is given whenin the opercular area to prevent gill damage.

Gravid females that are expelling eggs while in the net are held tail up oron their back, and the vent is blocked with a finger to prevent further egg losswhile handling. Brood fish are placed in a 100-gal tank containing lake waterand supplied with 1-2 L oxygen/mm dispensed with airstones. Fresh water issupplied as necessary with a 12 volt pump. A burlap tank cover is used to reducepotential stress from bright sunlight. The standard project boat is 18 ft long,powered by a 150 hp outboard engine. The size and power of this equipment isdeemed necessary due to payload, distance from the boathouse and potential foulweather conditions.

Broodfish are returned to the boathouse when the carrying capacity of thetank is reached. The actual number of broodfish in any haul varies due to fishsize and sex ratio, but generally 25-50 fish can be held safely in the tank.Fish are transferred to a holding tank inside the boathouse. The tank issupplied with recirculating lake water and provided with 1-2 L oxygen/min. Anoverhead counter-weighted submersible pump is lowered to empty and refill theboat tank for additional trips to the nets. Broodfish are sorted by sex andripeness. Males are placed in a 4x4x4 ft holding net (1-in bar mesh) suspendedthrough the floor of the boat house. "Green" females are held in asimilar holding net. They are checked each morning and ripe fish are stripped.Fish that are still green are marked with a hole punch in one lobe of the caudalfin and held back another day. Females that have not ripened after two suchmarks are released. Males as needed are placed in a tub with oxygen andrecirculating water on the spawning table.

The dry method of spawning is used in Colorado. A female and the spawning panis wiped dry and eggs are extruded from the fish into the pan by firm pressureto the abdomen. We have found that wearing rubber surgical and/or wool glovesand using a closed finger rocking motion from the tips of the fingers to theback of the hand is an effective method for stripping eggs. This technique isthought to be less harmful to the fish. Less scale loss and mucus production isobserved compared with other techniques that have been used. However, personnelwith small bands may have difficulty using this technique. Large females (8-15lb) are always handled by the head and tail rather than by the tail only.Handling a large fish by the tail can only result in skeletal damage.

Fresh semen from two males is used to fertilize the eggs.Extended semen is used when males are in short supply. Fertilized eggs arecovered with water and stirred for 90 s with a feather. Water is then decantedfrom the eggs. This step is done as quickly as possible, and can requireadditional repetitions if blood or fecal matter is present.

Egg clumping will occur if too much time is spent cleaning the eggs.

After fertilization and cleaning, a mixture of Fullers Earth and water (3-4cups Fullers earth to 1 gal of water) is added to the eggs and stirred for anadditional 90 s to remove the sticky matrix that causes eggs to clump duringincubation. The mud solution is decanted and the eggs are washed with cleanwater to remove residual mud and blood. Eggs are then poured into a Saran cloth(32x32 mesh/in) covered egg box. Each box is capable of holding 2 -3 millioneggs. The boxes float in a shallow oblong tank that is supplied with oxygen andlake water. Minimum water hardening time is 1 h. After the eggs arewater-hardened, they are dipped from the egg boxes and placed into anappropriate sized cooler. Coolers should not be filled more than two-thirdsfull. Additional egg swelling can exceed the cooler capacity and oxygendepletion can result in substantial losses. Fresh water is added to completelyfill the containers and lids are secured. The coolers are then transported tothe hatchery for tempering, enumeration, and jar incubation in well water.

HatcheryTips
By:  MTAN

Are you having problems keeping small fry and debris off yourtail screens?  The folks at the Lacdu Flambeau Reservation have developed an air bubbling system that eliminatesthis problem.  The system involves a flexible air line inserted into asection of copper pipe.  The pipe is cut to a length that covers the entiretail screen (or stand pipe) area.  Holes (1/16 inch) are drilled into thecopper pipe that will produce large air bubbles.  The air line has a valvethat allows the operator to adjust a level of air flow to provide water currentswhere fry are floated away from the tail screen area.  Anotherbenefit of this system is that additional oxygen is added to your rearing tank.

The MTAN recently had the opportunity to use the new microbubbleoxygen diffusers that are now on the market.  WaterManagement Technologies is just one of many outlets for this fineproduct.  These diffusers produce a cloud of extremely fine bubbles (100 to500 microns).  The smaller the bubbles, the more efficiently the gas willbe absorbed into the water.  The end result is healthier fish due to ahigher oxygen absorption rate.