Dedicated To Tribal Aquaculture Programs
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September 1994 ~ Volume 9 | |
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Topics of Interest:
Sucker Propagation and Rearing
SUCKER PROPAGATION AND REARING
By: John B. Daily, Aquaculture Consultant, 7300 113th Ave. No., Champlin, MN 55316 612-323-0772
Live bait fish of major importance in Minnesota includes several species of minnows. Bait minnows used include: fatheads, several species of chubs, shiners and certain species of dace. The term minnow is commonly used to include members of the minnow and sucker families and implies a small bait fish.
The white or common sucker is a well known species in Minnesota. It is found in lakes and streams throughout the state but they are mostly in the northern areas. This species is often associated with walleyes, northern pike, and lake trout and is least abundant in lakes of southern and western Minnesota where there are large populations of carp, bullheads, and buffalo fish. The most important bait fish species cultured is the fathead minnow. The second most important, which I will discuss in further detail, is the white sucker.
Back in 1980, when the last complete survey of the minnow industry occurred, the white sucker constituted approximately 34% of sales (which was valued then at $7.6 million dollars), and by the year 2000, the value of sales may be closer to $17 million.
Sucker propagation has been in place within Minnesota for well over half a century. Suckers are anadromus species which run up streams in the spring to spawn, but also may spawn in school areas of lakes. They select sites where they can concentrate their spawning activities. Spawning usually occurs when water temperatures are between 50E and 65E, which is usually the last part of March or early April. In streams the sucker spawning run often follows the walleye spawning cycle.
EGG STRIPPING
Collecting fish on the spawning site requires ample space to crib fish to be sorted before spawning. The most common error which occurs is the desire to collect as many eggs as possible and as soon as possible. To insure the highest amount of fertility (of those eggs taken) you must not force the females to expel all her eggs as many are not completely ripe. Stripping only those females which are clearly mature will result in a higher percentage of eggs to become fertilized. Female maturity is dependent on water temperature, current, and weather conditions. Even though female suckers have been known to contain as many as 130,000 eggs, stripping operations will not produce that many per female. The yield is from 4,000 to 40,000 eggs because not all their eggs are ready for release at the same time. If some green females are cribbed do not hold them for very long, especially if they do not ripen within 72 hours. After this time they should be released. Sorting of fish may be done by hand or dip nets. Do not pick fish by the tail or across the eyes. Do not crowd fish too tightly, so that ripe females prematurely eject their eggs. Stripping can be performed standing or sitting, but it's generally easier if a small table is used.
If during the stripping process, water temperatures began to warm-up, then any cribbed fish should be checked again for ripeness. When stripping fish, hold the fish in a natural position. Do not bend the body or tail to extremes. Use the flat of the index finger at right angles to the belly. Do not apply extreme pressure, as eggs should discharge easily if the fish is ripe. Undue handling and pressure can cause ruptured eggs and or internal injury to the fish. Do not hold the fish upright and shake, as few eggs are obtained by this method. NOTE: Sucker eggs are naturally semi-buoyant and somewhat adhesive.
The next operations are critical and should be fully understood to ensure a high percentage of fertilized eggs.
Strip the female(s) in a semi-dry container, with no excess water. Using a hard plastic bowl seems to work best, as the eggs are less likely to adhere to the surface, and the bowl's shape permits easy mixing of the eggs and sperm. The trigger which starts the egg and sperm to interact is water. No more than 2 or 3 females to a pan should be considered. No excess water should be allowed in the pan until sperm and water are added at the same time.
Sperm in water is capable of fertilizing eggs for a maximum of only 20 to 30 seconds. While some fertilization may take place after this time, it is so negligible it can be disregarded. This means the operator has no more than 30 seconds to thoroughly mix the eggs and milt. After 30 seconds, fresh sperm from another male is needed. Two males to each female is the preferred ratio.
It is also believed that eggs are capable of being fertilized for up to 2 minutes, but after 1 minute when coming in contact with water, the number of eggs which retain their ability to become fertilized drops drastically. By mixing eggs and sperm rapidly and thoroughly with water you should be able to raise the percentage of fertilized eggs to about 90%. To mix, use a block of goose feathers, a soft rubber spatula, or other suitable soft device. Use extreme care not to rupture the eggs. Stripping of females should be done keeping in mind the allotted time limits. After fertilization the bowl should be set aside for another minute or two then the eggs should be "mucked". Muck (composed of bentonite-a fine clay) should be added in sufficient quantity to coat the eggs to prevent clumping and to remove the adhesiveness of the egg. Muck can be mixed in with the eggs using a block of feathers, or swirling the bowl. Eggs should remain in the clay for 1 to 2 minutes to obtain a proper coating. The eggs may then be washed in a screen cradle below the stripping site and the clean eggs can be water hardened in the cradle or placed in a tub or other holding container. The screen washing cradle may be constructed of a brass screen that has 58% open areas and 24 openings per linear inch. CAUTION: Eggs are very sensitive to UV light and must be covered at all times whether in the cradle or in a tub. Fresh water should also be added to the egg holding container every 10 to 20 minutes.
EGG HARDENING
If eggs are allowed to water harden in a cradle, allow 4 quarts per 30 inch cradle and hold them in good flowing water. A lesser amount of eggs should be used if there are suspected water problems. If tubs are used, allow approximately 15 quarts of eggs per tub. This will also require periodically changing the water for oxygen renewal. In most instances, egg hardening may take place in the hatchery, by siphoning water from the battery or attaching a hose to a spigot, then to the tub of eggs. To prevent eggs from sticking to the bottom inside edges of a tub you may add a bead of silicone caulking around the bottom edge. If possible, protect eggs from UV light and weather extremes inside or outside the hatchery.
Sucker eggs must be allowed to water harden before they can be counted and placed into hatchery jars for further incubation. Eggs not properly water hardened and placed in jars will have a tendency to adhere in masses. After fertilization cell division will begin in approximately 8 hours, unless the water is very cold. There should be no further handling of the eggs until eye-up.
EGG TRANSPORTATION
Depending on the distance of travel from the stripping site to the hatchery, garbage cans, plastic bags or milk cans may be used to transport the eggs. Avoid undue shock from splashing of the water. This may be accomplished by using containers with tight lids filled half with eggs and the rest with water. As a general guideline a garbage can will hold approximately 10-20 quarts of eggs, and a plastic bag 5-8 quarts. Add oxygen to plastic bags and tie shut, unless your trip to the hatchery is less than 30 minutes. Plastic bags can be placed in another suitable container (filled with water) that can further cushion the eggs. Upon arriving at your hatchery the eggs may have to be tempered. NOTE: A temperature variance of more than 5E F. will require some tempering.
HATCHERY OPERATIONS
To reduce the potential for early fungal and bacterial infections within the hatchery system, it is best to disinfect the facility (before use) with chlorine.
Transferring eggs to jars is best achieved by dipping from the egg container (tub) into a tipped jar (with some water in it), or by using a funnel which is placed in the jar of water. This technique will help to avoid induced shock to the eggs. Do not dip eggs dry, but always have water for buoyancy. If incubation jars do not have quart graduations along the side, then you should have a measuring stand to avoid overloading the jar. Incubation jars can be marked by using a good quality transparent tape marked with one quart graduations. Each jar may contain 2.5 to 3 quarts (maximum) for incubation.
As the jars are put on the hatching battery, water flow rates should be adjusted to prevent eggs from flowing out or from lumping together. Use the least amount of flow to achieve these objectives. Hatching jar stand pipes should be centered to roll eggs equally in the jar (plastic jars will center the stand pipe automatically). A number of empty jars should be available for use as hospital jars for egg clean up. This is done to prevent dead or fungused eggs from affecting the good eggs within each jar. During the incubation process the eggs are very sensitive to shock until they are eyed, so to remove the bad eggs use a siphon hose, with the bad eggs being placed in the hospital jars. NOTE: Removing bad eggs will also remove some good eggs, this is why the hospital jars are used.
It is quite common for dead eggs to develop fungus during incubation. If not controlled the fungus can spread to live eggs and reduce hatching success. A formalin-F drip station at the water inlet can be used which delivers a ratio of 1:6,000 parts in 15 minutes. This treatment process should be avoided during the first 7 days of incubation or after eye-up. If eggs are not treated it's possible the eggs will clump and start to float out of the jars. This can be stopped by slowing water flow, siphoning, or stirring the eggs with a feather. Higher incubation water temperatures will accelerate egg decomposition and fungus growth. Dead egg removal must be done until the eggs are well eyed. CAUTION: When removing bad eggs into a tub, observe if a oil slick appears on the tub water surface, if this occurs then the eggs are being handled too roughly and the eggs shells are rupturing. After the eggs are fully eyed the jars can be cleaned, the eggs measured and then rejarred. Fry tanks should also be cleaned and made ready for the fry hatch prior to egg eye-up.
EGG MEASUREMENT
The hatchery operator should know the egg size to determine the actual amount of eggs on hand. Once the eggs are placed on the hatching battery, a cross section of eggs should be taken for measurement. A "pig trough" is a measuring device that allows the hatchery operator to determine the actual size of the egg and then convert the number of eggs in a 6-inch metal trough to the number of eggs in one quart. Taking random samples across the hatching battery and making 10 individual counts will give you the overall average size of the eggs which will allow for the number of eggs per quart.
OTHER HATCHERY PROBLEMS
Debris in water can usually occur if water is drawn from a pond, lake or stream. Debris can slow or stop water flow to the jars and injure the eggs. Debris may be removed by using a screen box beneath the water inlet to each battery. Brass screen similar to that used in egg cradles is preferred because it is durable, and can be scrubbed many times. Plastic screen can be used but isn't quite as durable.
A sudden increase in water temperature can cause gas bubbles to appear. This may occur if using surface water or heating well water. This problem may develop at any stage of rearing (including the eyed stage). Gas bubbles can float eggs out of the jars unless the spigots are screened. To reduce this problem you can add colder well water to the inflowing surface water. If you are heating water then heat the incoming water several degrees above the temperature you want to mix with the eggs, then add cooler well water to bring the temperature down to the proper level. Extreme agitation of water at the head box will assist in dispersing air bubbles and some gases. Pure oxygen injection will also reduce gas bubble problems. Water should be run slowly through the jars and the top row of jars should not be used for hatching if possible.
EGG HATCH
Once the eggs are fully hatched, sucker fry tend to stay in the jars. At this point you may wish to dump them in distribution containers, or place the fish into the fry tank for later distribution. Egg shells can cause the fry tank screens to clog. Bubblers against each outlet screen will be necessary. Do not allow the fry tank to become heavily loaded; stocking of fry should began when sufficient numbers appear in the tank. NOTE: Within 4 days of hatching a thunderstorm can cause a premature hatch of your eggs. Also, never chemically treat eggs within 3 days of hatching. Screens may have to be brushed when fry and egg shells begin to plug the screen openings. If screens become plugged than the tank will overflow and the fry will be lost. Throughout the whole hatchery operation, it is very important to have a knowledgeable person on night duty to monitor the development of the hatchery program.
FRY DISTRIBUTION
To move the appropriate number of fry to ponds the weight displacement method should be used. Using a floor scale and a tub, add water to the tub to a preset weight. When fry are removed from the tank (using a fry seine), drain most of the water from the net and place the fry into the tub. By knowing the number of fry per ounce you can calculate an average number of fry in each tub. Should you wish to measure smaller amounts of fry I have another method which works very well . Please contact me should you wish further details.
Fry can be distributed in a number of ways depending on pond location, distance to travel and number of fry to be moved.
A standard distribution tank (130 gallons of water capacity) can hold 750,000 fry (with the use of oxygen). This is the least approved method.
Large plastic bags can be used with about 75,000 fry/bag injected with pure oxygen.
A garbage can with 20,000 fry and no air can be used for very short trips (less than a 2 hr.).
NOTE: Before stocking you must avoid thermo-shock. Taking pond temperatures is very important. Again the 5E variance holds true. Pond temperatures greater or less then this require tempering the fry. Place the container in the pond and slowly add water to acclimate the fry. Stocking should be on a quiet shoreline or even off shore to avoid fry from being washed back into shore. If possible, fry should be stocked when pond temperatures are rising, and a good plankton population is developing.
TIPS ON PONDS
EXAMPLE OF A POOR POND--Ponds less than 5 feet in depth with water fertility of more than .100 ppm of phosphorus and 1.75 ppm of organic nitrogen, or a maximum blue-green algae population of more than 300 pounds per acre foot of water will not produce suitable crops of sucker fingerlings.
EXAMPLE OF A GOOD POND--Ponds best suited for sucker propagation are generally 5 to 10 acres in size, 5 to 10 feet deep, moderately fertile, and fairly free from summer kills. Most ponds have adequate natural sucker food supplies for suitable growth in a summer period. Length of growth is generally a function of sucker density. A survival rate of 20 to 30% for stocked fry is very acceptable. Understocking produces fewer fish, but overstocking wastes fry.
Average Minnesota production in sucker ponds shows a high of 25,000 to a low of 1,500 fingerlings per acre. Periodic cropping greatly increases sucker weight. Also, be sure to monitor oxygen levels throughout the growing season and throughout the winter period (should you wish to over winter your fish).
Management Options To Consider When Planning A Fee Fishing Operation
By: MTAN
Fee fishing operations should have limited access for security purposes. Irregular shaped ponds of 1/2-2 acres will provide a more natural and aesthetic fishing environment. Smaller ponds are also normally easier to manage. Two or three ponds provide management advantages over a single pond operation. If fish are off flavored, become diseased, will not bite, or if pond repairs are needed, the business will not meet its full potential. Drain structures should be installed to allow rapid pond dewatering.
Shallow pond areas, less than 2 feet in depth, should be avoided since they promote aquatic plant growth and unfavorable water temperatures. If possible, fee fishing ponds should be constructed with a 3-5 foot depth. A smooth pond bottom permits the seining of the pond for good pond management. Adequate parking facilities and a combination ticket/concession stand should be located at the main entrance. Property liability insurance should be considered, or accident release forms should be signed as customers enter the property. Some fee fishing operations are open 24 hours, 7 days a week, while others have limited hours of operation.
Fee fishing operations often charge either a general admission fee and an additional fee per pound of fish caught. Selling fish by the pound provides more accurate fish stock records but requires an attendant to weigh the fish as customers leave. Customers should be discouraged from returning captured fish to the pond since the fish often do not survive.
Bonus ponds may be stocked with larger fish and have been used successfully to attract fee fishing customers. Stocking other than the primary fish of interest into a fee fishing pond can make pond management difficult and should be avoided. Feeding the fish while they are in the pond will allow the fish's immune system to combat disease and to maintain its body weight. Supplemental feeding will keep the fish healthier and hungrier.
Fee fishing operations make most of their profits from the sale of concession items. Fishing tackle, baits, soft drinks, and candy are commonly sold. Fishing rods and reels may be sold or rented. Cane poles or spin casting gear is most frequently used. Deposits may help discourage rental equipment vandalism. Many fee fishing operations use holding tanks to sell additional fish to fishermen, or to customers not interested in fishing. Fish cleaning ($.25-.35 per lb or per fish) and food vending services could also be provided. Adequate restroom facilities are necessary to insure the success of the operation. Consult the county health department about existing regulations regarding these types of facilities. Some fee fishing operations provide alternative activities for nonanglers such as pony rides, game rooms, playgrounds plus picnic and camping.
Aesthetics, facility cleanliness and safety are important details which can determine an operation's success. Providing paved, or gravel pond banks which are clear of vegetation near the waters edge will improve accessibility. Benches, picnic tables, shelters, and shade trees may be located a short distance from the pond. Litter containers and life saving gear should be readily accessible. Entrance signs displaying regulations such as the limit of two fishing rods per person, fish size or quantity limits, and prohibiting the use of alcohol and abusive language are also useful management tools.
Many fee fishing operations depend on repeat customers and word of mouth advertising to attract business. Attractive roadside signs as well as radio, television, and newspaper advertisements may also attract customers.
A fee fishing operation's success will depend on the manager's ability to run a business and manage the public, in addition to managing the fish. It is important to remember that fee fishing customers expect to catch fish.
Comparison of Two Methods of Oxygen Supplementation for Enhancing Water Quality in Fish Culture
By: Speros Doulos, Anthony Garlind, John Marshall and Mark White
U.S. Fish and Wildlife Service, Erwin National Fish Hatchery, Erwin, Tennessee 615-743-4712
Taken from the Progressive, Fish-Culturist 56:130-134,1994
In recent years, several methods of injecting pure oxygen into fish-rearing water have been developed. The use of pure oxygen for fish culture can increase fish production and reduce nitrogen saturation. Some oxygen supplementation techniques contribute to excessively high total gas pressures that can adversely affect fish health. The sealed column, however, has proven to be one of the most effective devices for adding pure oxygen to fish-rearing water.
The spring water supply at Erwin (Tennessee) National Fish Hatchery consistently produces water with dissolved oxygen (DO) at less than 90% saturation. The combination of limited spring water flow, serial water reuse, and pumped reuse results in dangerously low DO levels throughout the hatchery. In addition, nitrogen saturation levels regularly exceed 120%. An oxygen supplementation system was installed to increase DO and reduce nitrogen saturation where water first enters the facility at a place where two different methods of oxygen supplementation can be used. Pure oxygen can be added directly to two sealed columns or injected into the main pump line through a pipeline manifold. This study was performed to evaluate the effectiveness of these two methods of oxygen supplementation.
Results and Discussion
Data collected from the main spring water supply standpipes (no oxygen supplementation) were consistent throughout the study. Incoming DO averaged 8.6 ppm (range, 8.4-8.7 ppm); mean oxygen saturation was 86.3%. Mean nitrogen saturation was 121.2% (range, 120.5-121.6%), and average TDG saturation was 113.7% (range, 113.3-113.9%). These data are consistent with baseline water quality data collected during the previous year.
The sealed column oxygen injection site provided higher raceway DO, lower nitrogen saturation, and lower TDG saturation than the pipeline manifold site. These data were obtained from the mixing of 358 gal/min of oxygenated pumped water effluent with 1,044 gal/min of main spring water that received no supplemental oxygen. The highest DO levels were achieved with sealed column oxygen supplementation at a gas-to-liquid ratio of 2.2%, which resulted in a 73.5% increase in raceway DO (to 6.33 ppm) and increased oxygen saturation to 149.3%. This method of oxygen supplementation reduced nitrogen saturation to 93.1% and TDG saturation to 105.0%. By comparison, pipeline manifold oxygen supplementation at a gas-to-liquid ratio of 2.2% resulted in a 53.7% increase in raceway DO (to 4.83 ppm) and increased oxygen saturation to 134.6%. Nitrogen saturation was reduced to 99.0% and TDG saturation to 106.1%.
The greatest oxygen transfer efficiency was achieved when oxygen was added to the sealed columns at a gas-to-liquid ratio of 0.7%. Oxygen supplementation via the sealed columns was consistently more efficient than oxygen additions through the pipeline manifold. Oxygen transfer efficiency was reduced as the gas-to-liquid ratio was increased for both methods.
Dissolved oxygen measurements taken directly from the sealed column effluent showed small variation, 1.5-2.7%. Percent variation was far greater when supplemental oxygen was added through the pipeline manifold, 54-63%. Column water flows were checked following the collection of effluent DO data. Column water flows were initially set at equal flow rates (179 gal/min through each column). Whereas minor variations in water flow occurred when oxygen was added directly to the sealed columns, pipeline manifold oxygen injection resulted in a 21% variation in column water flow. Colt and Watten (1988) described bubble formation when pure oxygen was injected into air-saturated water. These bubbles typically form at elbows, pipe transitions, and other areas of low pressure or high turbulence. Oxygenated water within the pumped water line at the Erwin hatchery flows through five elbows and several pipe transitions. It appears that gas bubbles collected near the top of the pipeline, reducing the cross-sectional area of the pipe and ultimately changing water flow. Resulting variations in column effluent DO were impossible to control when supplemental oxygen was added through the pipeline manifold.
Based on our tests, oxygen injection directly into sealed columns is a more effective means of oxygen supplementation than oxygen injection via pipeline manifolds.
WARTS ON A WALLEYE
By: Terrence Ott, U.S. Fish and Wildlife Service, La Crosse Fish Health Center, La Crosse, WI 608-781-6238
Warts or Lymphocystis, although rarely lethal, is a chronic infectious viral disease caused by an iridovirus that results in uniquely enlarged cells, appearing as warts, in the skin and fins of walleye and most centrarchids in North America.
The highly dermatotropic lymphocystis virus infects the cytoplasm of fibroblastic cells of the interstitial connective tissue. Infected skin and fin cells in the course of their cytological change do not multiply, but enlarge from their normal size by a factor of 50,000 to 100,000.
The name lymphocystis disease was coined by an investigator during the early 1900's on the presumption that the giant skin cells represented a protozoan parasite. The parasite said to be involved was Lymphocystis johnstonei the source of the modern accepted name of the disease.
The viral disease has been reported in at least 81 species of fishes from 33 taxonomic families and seven taxonomic orders. The most susceptible species are walleye, sauger, pike, and panfishes. The disease has not been reported in salmonids.
The viral pathogen is typically dermatotropic (has affinity for dermis) and superficial. It is considered to have low virulence, since the course of this disease is exclusively chronic and liver functions are hardly impaired. Numerous warts can be unsightly and the marketability of obviously infected walleye is limited. Mortalities due to lymphocystis disease are probably rare, but the disease can occur year round depending on water temperatures. The developmental period for the virus to produce warts in the walleye takes about two weeks at 12EC.
Infected walleye behave normally but extensive warty growths on the fins can slightly affect swimming speeds, and heavy infections on the head region may hinder vision and feeding movements. Any walleye living with lymphocystis lesions for a few months to a few years without being destroyed by the disease will spontaneously slough the warty growths and remain free of the disease. Contact transmission is the principle means by which the viral agent is spread. External surfaces, including the gills, are the chief portals of entry. The oral route seems not to be involved, and furthermore, no evidence exists for vertical transmission (via the gametes). Factors such as high population density, external parasites, and trauma enhance transmission of the disease. External trauma has been implicated in transmission of the disease during spawning from aggressive behavior over spawning and mates, as well as, from human activities such as netting, fin clipping, or tagging.
A prophylaxis treatment is only possible by placing walleye in quarantine for at least 2 months. The best method to eradicate the contagious viral agent from a walleye population is by destroying all infected fish from the population.
Remember! Transporting walleye with warts is the fastest way of spreading the virus from one watershed to another.
THE CAILLOUET FLOATING RACEWAY SYSTEM A STEP FORWARD FOR FISH CULTURE
By: Dan Selock, Mid-Continental Fisheries, P.O. Box 1177, Marion, Ill. 62959 618-997-2117
As aquaculturists, we often search for the "ideal culture fish," depending upon our length of growing season, average water temperature, and markets. For some it's channel or blue catfish, baitfish, tilapia, largemouth bass, or even crawfish. For others it's trout, salmon, hybrid striped bass, walleye, or yellow perch. Along with this search for the best fish species is also a search for the "ideal culture method." Which method, open pond, cage, raceway, or recycle system, best fits our resources of land, type of water impoundment, water supply, existing equipment, labor force, and investment capital? We all have our unique situations and problems.
Recently, an innovative fish culture method has surfaced - the Caillouet Floating Raceway System (patent pending). It is the reorganization of existing, proven ideas into a new form. The system incorporates the advantages of raceways with the economy of airlift pumping and the need for solids removal, all done in an existing body of water. The system consists of four raceways divided by wooden walkways. Pond water is airlifted into one end of the raceway at a rate of 300 to 500 gallons per minute. It flows through the solid walled raceway, passes through a clarifier, and is discharged back into the pond for denitrification and aeration. Each raceway is four feet wide, four feet deep, forty feet long and holds about 500 cubic feet of water. A complete water exchange can be made in as fast as eight minutes. Solid wastes are collected in the clarifier at rate of 60% to 90%, depending on fish species and size, and removed from the pond to be used as fertilizer on land. Channel and blue catfish and trout have been successfully stocked at the density of 12 fish per cubic foot of water. Higher stocking densities are predicted with more experience. Due to the economy of airlift pumping, nearly three million gallons of water can be moved through the system for about $4.00 per day.
Drs. Michael Masser and Kyung Yoo at Auburn University presented information on a prototype floating raceway system for channel catfish in March of '92, and Masser, Hawcroft and Yoo presented information on raceway waste removal in January of '94. Both systems were similar to the Caillouet system, but not as commercial in size nor believed to be as efficient in waste removal and water movement. Regardless of the size and design, the researchers stated that "data from '92 suggested that growth, survival, and feed conversion of the In-pond Raceway system are superior to that of floating cages." Several aquaculturists feel there is a need for further research to compare floating raceways to open pond methods regarding production rates and costs, especially using the raceways as nursery facilities.
A World Aquaculture Note in March of '89 written by a fellow aquaculturist in Norway stated that for salmon culture "sea cages represent a simple and inexpensive technology, but problems from self-pollution due to waste feed and feces, high levels of ammonia, reduced water circulation, and availability of oxygen due to fouling of nets, sea lice, algal blooms, and disease are often experienced...raceway (floating) fish contained more white muscle, which is higher quality, than red muscle." After slaughtering and quality ranking, 97% of the raceway fish were of superior quality , compared to 87% of the net pen fish. At the end of the experiment, the total growth of the raceway group was 38% higher than the control group. It was mainly the swimming muscle that had increased in weight. Raceway fish also had a higher condition factor and lower mortality than fish in net pens.
John Morrison and others at the Southeastern Fish Cultural Laboratory in Marion, Alabama, used the Caillouet design and recently compared the survival of floating raceway reared catfish fry to pond reared fry. Predation by insects and/or wild fish and feeding efficiency were better controlled in the raceways. Difficulty was experienced with predation and feeding efficiency in the open pond. Losses were reduced in the raceway.
Currently there are two Caillouet Floating Raceway Systems in operation. One, which is in Brewton, Alabama, is rearing channel and blue catfish at a stocking density of 12 fish per cubic foot and using demand feeders. Wayne Caillouet, the system's inventor, is pleased with growth rates, feed conversions, and rate of survival. The other four-raceway system is near Marion, Illinois, and contains channel and blue catfish and yellow perch at this time. Rainbow trout were raised during the winter months. A small hatchery was constructed on the floating dock during the spring and used air from the system to hatch channel catfish eggs. Catfish broodstock were paired-up in one of the raceways with dividers - "motel rooms." The fertilized eggs were moved from spawning cans in the raceway to the hatchery tanks, only a matter of about 12 feet apart. The eggs hatched, sac fry were moved to holding tanks, also on the floating dock, where swim-up fry were fed until they reached about an inch in length and then stocked back into one of the raceways. So, the system allows the fish culturist to manage all stages of fish growth, from broodstock to egg to fry to fingerling to stocker or food size. Bird predation started to be a problem before a roll of poultry netting was installed to cover the raceways. This was especially important with the smaller fish. The solid waste collected from the clarifiers has been found to have a nitrogen - phosphate - potash ratio of 18 - 13 - 3. Water temperatures have remained relatively steady compared to the air temperatures, and no water quality problems have been experienced. Fourteen more raceways are being constructed for the next growing season to raise yellow perch, hybrid striped bass, blue catfish and white suckers. A processing plant is also in the planning.
Is this the "ideal culture method?" Well, nothing is ideal, but this system does allow you to raise a variety of fish species in a small space, observe feeding behavior, and sort and grade easily. Treatment for external parasites can be performed with a controlled bath in a single raceway at a time, versus treating the whole pond. Off-flavor is not much of a problem, since current flow keeps the entire pond mixed and aerated. Harvest is simple and inexpensive at any time, in any weather. Most labor costs are less. An existing body of water deeper than six feet can be used. And this system offers the aquaculturist a practical way to protect small fish from those darn birds. You be the judge. Call Wayne at 205/809-0241 in Alabama or Dan at 618/997-2117 in Illinois for their testimonies.
Is There A Phone Dialer In Your Hatchery's Future
By: Steve Mortensen, Fish and Wildlife Biologist, Leech Lake Reservation, Division of Resources Management
The MTAN contacted us awhile back and requested that we put together a short article on the phone dialer we use in the fish hatchery to monitor its vital functions and to alert us in the event of a problem. We have been using phone dialers for close to 10 years now, and during this time they have paid for themselves many times over by alerting us to problems before they become disasters. This is not to say that they have averted all disasters and that we advocate them as a substitute for simple, reliable systems and good routine maintenance, but they are definitely useful pieces of equipment.
Phone dialers come in a variety of models and can cost anywhere from about $100.00 to thousands, depending on features and manufacturer. The particular dialer we are using at this time is a Sensaphone7 Model 1100, and it has proven to be more reliable than previously-used models and has more features. As I recall, it cost between $200.00 and $300.00 when purchased four years ago.
Basically, a phone dialer is an alarm system that has a built-in telephone that will call you in the event of a problem. This particular model monitors the electrical power, room temperature, noise level, and up to three separate external circuits of your choosing. The temperature monitor portion of the dialer can be set to call you in the event that the temperature goes higher or lower than the levels you set. Remote temperature sensing is also possible with an optional probe. If you need to monitor more than three items at your facility you can wire more than one sensor to each of the three circuits. Almost any type of switching device that opens or closes a circuit can be used with the alarm. These switches will have to be purchased or built to suit your hatchery's needs.
In the event the alarm is tripped, it will start calling the phone numbers you have programmed into it until it contacts someone and that person calls the alarm back to prevent it from calling the next person. In addition, you can call the alarm at any time and it will give you a run-down of temperature, electrical power, and alarm conditions.
Overall, the Sensaphone 1100 has proven to be a reliable unit with few problems. The manual does a good job of explaining its features and how to program it, but it will take a little study. You should remember that you will also need to provide all the external alarm sensors, and unless you have a basic working knowledge of electricity you will have to hire someone for this work.
For more detailed information on our experiences with phone dialers, feel to call us at 218-335-8240. Information on the Sensaphone can be obtained by writing to Phonetics, Inc., 901 Tryens Road, Aston, PA 19014 or by calling them at 215-558-2700.
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Product and company names mentioned in this publication are for informational purposes only. It does not imply endorsement by the MTAN or the U.S. Government. |
