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Minnow Propagation

By JOHN DOBIE Aquatic Biologist Division of Game and

CONSERVATION BULLETIN NUMBER 13

MINNESOTA DEPARTMENT OF CONSERVATION CONSERVATION BULLETIN NO. 13

Published by the Minnesota Department of Conservation, Bureau of Information, 1948.

Permission to reprint is granted if proper credit is given. Send marked copy.

STATE OF MINNESOTA

Luther W. Youngdahl, Governor

Chester S. Wilson, Commissioner E. V. Willard, Deputy Commissioner Minnesota Department of Conservation

FRANK D. BLAIR, Director H. G. WEBER, Director DIVISION OF GAME AND FISH DIVISION OF FORESTRY C. T. EKMAN, Director L. E. FIERO, Director WATER RESOURCES AND ENGINEERING DIVISION OF STATE PARKS RAY D. NOLAN, Director CARL W. MOEN, Director DIVISION OF LANDS AND MINERALS BUREAU OF INFORMATION

PUBLICATIONS Brendan J. Connelly, Editor 633 State Office Bldg., Saint Paul 1

Thirteenth of a series . . . Propagation is the thirteenth of a series of conservation bulletins published by the Minnesota Department of Conservation. The aim of each publication is to present a comprehensive treatment of a single natural his- tory or conservation subject. Such coverage, which is more detailed than is possible in a single issue of THE CONSERVATION VOLUNTEER, our official maga- zine, constitutes a progressive addition to the informational services offered by the Department of Conservation. Requests constantly come to our department for authentic information about the propagation and management of . In order that the pub- lic may have a better understanding of the subject, John Dobie, one of our aquatic biologists, has prepared this series of informative articles. Chester S. Wilson Commissioner of Conservation CONSERVATION BULLETIN NUMBER THIRTEEN

Minnow Propagation

PREFACE

Postwar fishing pressures in Minnesota have resulted in heavy de- mands for more bait minnows. Minnow dealers have been forced to obtain bait from already heavily fished streams, and have found it necessary to search for new waters. The Minnesota Department of Conservation feels that the present bulletin will help bait dealers to make better use of the minnows they now obtain from native streams and to rear their own in artificial ponds when necessary. It is hoped that this bulletin will contribute towards easing the bait minnow shortage. Frank D. Blair Director Division of Game and Fish

Minnesota Department of Conservation Saint Paul, Minnesota 1948

0,410010, w

BRASSY MINNOW

BLUNTNOSE MINNOW About 2,890,000 minnows are sold to fishermen each week. Artificial Propagation Needed To Relieve Minnow Shortage

John Dobie A large percentage of tourists fish that are killed during seining come to Minnesota in order to operations or those that are lost in to enjoy the good fishing of transportation and holding of the fish. Eour 10,000 lakes. They arrive in such This heavy drain on the natural sup- numbers that the tourist business is ply of bait fishes has resulted in the third largest in the state. many periods of acute min- The sale of minnows and Minnow now shortage. suckers for bait is an impor- The natural habits of the Propagation tant part of this business. minnows have contributed to There are about 1,700 retail ' • ' this shortage. When spawn- and 150 wholesale dealers Number One ing, these little fish congre- in operation each year. gate along the lake shores The 1,700 retail bait dealers have and in streams where they are easy to an average sale of about one gallon seine. The bait dealer can then ob- of minnows a week. The number of tain all that he wants but there is minnows in a gallon varies according very little demand for minnows early to the size of the fish but 1,700 is in the spring. By midsummer, when an average number. Therefore, about the demand is large, the fish have 2,890,000 minnows are sold to the spread over the lake and are difficult fishermen each week of the 17 or 18 to catch in large quantities. Some week season. While this is a tremen- dealers have solved the problem dous figure, it does not include the by building or leasing ponds large enough to hold a supply from spring JOHN DOBIE is an aquatic biologist with to midsummer. the Bureau of Fisheries Research of the Divi- sion of Game and Fish, with which he has The geographical distribution of been associated since 1940. He previously was fishes has further complicated the employed by the U.S. Forest Service, the Wis- shortage of bait. The demand for consin Conservation Department, and as a bait fishes is heaviest in the northern wildlife technician with the Minnesota ECW resort area where the deep lakes and program. He is one of the authors of Propa- gation of Minnows and Other Bait Species. cold streams do not produce large

3 4 MINNESOTA DEPARTMENT OF CONSERVATION quantities of minnows. Consequently, tinues, the dealers may find them- large numbers must be hauled hun- selves in the same situation that ex- dreds of miles from the warm south- ists in Missouri where all the game ern lakes where the production is fish waters of the state are closed. high and the demand is low. Most In the northern part of the state of the long hauls are during hot where there are very few lakes that weather and the losses are high. can be managed entirely for min- A supply of minnows is necessary nows, the bait dealer will find it nec- to provide forage for the large game essary to raise his own supply in fish populations of our lakes and is ponds. For many years dealers have so important to the sport fishing in- been raising bait fishes in both natu- dustry that the Game and Fish Di- ral and artificial ponds and some have vision has developed a program of produced over 200,000 minnows per regulations to safeguard this resource. acre. In lakes and streams where the tak- There are many advantages in ing of minnows has endangered the minnow propagation. game fish populations, the seining of (1) The dealer can raise the spe- minnows has been prohibited. Exact cies of fish most suited to his trade. specifications on net mesh size, type (2) The dealer can be more sure of transportation equipment that can of a regular supply of minnows of be used, minimum aeration require- suitable size. ments for transportation and holding (3) Since the minnows are always tanks, and maximum load capacity available, they do not have to be for these tanks have been formulated seined up in large quantities with in order to eliminate much of the loss the resulting loss from handling and that occurs when minnows are han- holding of large numbers. dled. Some shallow lakes have been (4) The fisherman will be able to set aside as minnow lakes to be man- obtain a better conditioned bait and aged entirely for bait fishes. A few one that is more suited to his needs. have required stocking and others (5) The cost of raising minnows needed to be closed for one or more will often be less than seining and seasons but all are opened to com- transporting them from distant wa- mercial fishing whenever the fish ters. population is large enough to justify In Minnesota, an increasing num- that action. The operation of these ber of dealers have become interested lakes is an important step in improv- in raising minnows, so the Game and ing the bait situation. Fish Division has cooperated with If the present trend of closing wa- the Wisconsin and Depart- ters to the taking of minnows con- ments and the U. S. Fish and Wild- ARTIFICIAL PROPAGATION NEEDED 5 life Service in putting out a bulletin difficulties. There are many questions on the propagation of bait fishes. It that cannot be answered at the pres- is written to present all of the avail- ent time, but when the answers are able information on the subject and available, the bulletin will be revised to help the beginner over his first to include them.

One of Minnesota's many natural minnow ponds. Fertilizing a minnow pond.

Seining operations in an artificial minnow pond.

Many factors determine ideal pond site. Artificial vs Natural Minnow Ponds

Minnows can be raised in vari- sirable. ous types of ponds, either 4. At least one sloping, solid bot- natural or artificial. Natural tom shore is needed for seine land- ponds have no inlet or outlet and are ings. dependent on surface runoff for a 5. A pond with a high natural fer- supply of water while artificial ponds tility is more economical to operate are formed by a dam or dyke along because less fertilization is required. a water course. 6. Game fish in the pond will often Types of Ponds reduce the minnow popula- The natural pond is very MI N now tion to nothing. desirable because it can be Propa gation Natural ponds cannot be put into operation without expected to produce as many the expense of a dam or fill. minnows per acre as artificial All natural ponds, however, Num be r Two ponds, but when the cost of are not suitable for minnow purchase or rental is not too propagation. The shallow ones are high, they can be very practical. subject to oxygen depletion during These ponds cannot be harvested hot weather; those with a heavy completely because after the second growth of aquatic plants waste valu- seine haul, the catch of minnows is able fertility, and a pond full of too low to justify the cost of con- weeds and brush is difficult to seine. tinued seining. A natural pond should fill the fol- While the artificial pond is more lowing requirements if it is to be easy to operate and is more produc- used in minnow propagation: tive of minnows than the natural 1. The pond should be small be- pond, in many localities the low price cause a large one is difficult to seine of minnows will not justify the expen- and cannot be harvested completely. ditures of large sums of money for The most practical size is 1/2 to 1 acre. the dams and dykes needed in the 2. A depth of 5 feet must be main- construction of ponds. Construction tained throughout the summer if the and maintenance costs can be re- fish are to survive the hot weather. duced to the minimum by careful Fifteen feet of water is necessary to selection of the site. The pond should over-winter the minnows. be located in a natural depression 3. Aquatic vegetation is not de- where only a small amount of dyking 7 8 MINNESOTA DEPARTMENT OF CONSERVATION is required. A heavy soil will facili- concentrated in a pool of roily water tate the construction of dykes and during the period of seining. will eliminate the work of sealing the Minnows Most Suitable for pond with bentonite. A tight bottom Propagation is necessary to prevent seepage and Operation of natural and artificial the consequent loss of fertility. ponds will be similar in that both will require stocking, fertilization, weed Either springs or creeks are suit- control, and harvesting of the min- able for a water supply but those sub- nows. Before either type of pond can ject to violent floods are undesirable be started, the dealer must determine because of the danger to dykes and the species of minnow or minnows dams. In any case, provision should that will be raised. Local demand be made for by-passing the entire and the nature of the pond will often water source around the pond during determine the species that can be floods and when no additional water raised in any area, but over most of is required in the pond. Gravity flow Minnesota the golden shiner, fathead for the pond inlet and outlet are minnow, and the common sucker are necessary for efficient and economical the most practical. operation. Stocking the Pond Most artificial ponds are equipped Stocking the pond with the correct with a seining basin at or near the number of fish is very important be- outlet. Two types are in general use. cause it has a direct effect on the One is a walled depression a foot number and size of the minnows pro- deep inside the pond at the outlet. duced. An understocked pond will The water in the pond is lowered have a low production but the fish gradually until all of the minnows are will be of large size. An overstocked congregated in the basin. Seining can pond will produce a large number of then be done very easily with a small fish but they will be small. A pond net and a complete harvest of fish is receiving fertilization or artificial possible in a very short time. The feeding can be stocked heavier than other type consists of a seining basin one that receives no additional food. 3 feet deep outside the pond. This The stocking of fatheads has been basin is filled with water from the recommended at the rate of 1,000 to pond and all minnows are seined out. 5,000 adults per acre and golden The basin is emptied, refilled and shiners at the rate of 500 to 2,000 seined until the pond is empty. The per acre. Considerable work is neces- harvest by this method is complete sary on this subject before exact re- but requires more time. The main commendations can be made for all advantage is that the fish are not types of ponds. Even then the bait

MINNOW PONDS 9 dealer will have to try different rates are staked a foot off the bottom of on each of his ponds. the pond. The tray is constructed so For maximum spawning, the fat- that the fry can only escape when head should be supplied with spawn- they are strong enough to swim out ing boards. Rocks and limestone rub- through the coarse mesh of the top. ble on the bottom of the pond also This helps to prevent smothering of offer suitable spawning sites. The the fry in the silt and reduces preda- golden shiner requires aquatic vege- tion by carnivorous insects. Ponds tation on which to lay its eggs. Fil- heavily infested with insects should mentous algae is recommended for be treated with a thin layer of kero- this purpose. sene two days before stocking time in Suckers and stream minnows do order to kill the insects. not spawn in ponds so they are When suckers are stocked as eyed stocked as eyed eggs or fry. The eggs, the survival to salable-sized fish adults are caught in their spawning averages 10 per cent while the sur- runs and stripped of their eggs. The vival of fish planted as advanced fry eggs are fertilized in pans and are is 50 per cent. Consequetnly, the hatched at the hatchery. When the stocking rate for eyed eggs must be suckers are stocked as eyed eggs higher than for advanced fry. The (just ready to hatch), the eggs must following rates have been recom- be placed in cheesecloth trays that mended: State Method of Propagation Stocking Rate per Acre Minnesota Natural feeding 40,000 adv. fry Michigan Natural feeding 100,000- 500,000 eyed eggs Michigan Natural feeding 25,000- 100,000 adv. fry Michigan Artificial feeding 500,000-1,000,000 eyed eggs or fertilization 100,000- 300,000 adv. fry Pond Fertlization apply 500 pounds of barnyard manure For maximum production of min- per acre at least two weeks before the nows, the pond must be fertilized to fish are stocked. The manure will act increase the supply of natural foods quickly to produce the necessary or the fish must be fed artificially. foodstuffs for microscopic organisms Most Minnesota dealers prefer to fer- that are needed for food by the young tilize because it is cheaper and does fish. This bloom is maintained not require daily applications. The throughout the season by periodic ap- pond should be fertilized heavy plications of commercial fertilizer at enough to produce a bloom so thick the rate of 300 pounds per acre per that a hand is not visible at the depth season. Natural ponds should be fer- of a foot. The usual procedure is to tilized at a lighter rate because of 10 MINNESOTA DEPARTMENT OF CONSERVATION the danger of oxygen depletion at well the pond was planned and oper- times of heavy bloom. This effect ated. A pond that has been stocked can be eliminated in artificial ponds with the proper amount of fish and by running large amounts of fresh has been fertilized enough to produce water into the pond when the fish the maximum amount of food can be show signs of distress. expected to yield a large number of salable-sized minnows. On the other Artificial Feeding Large populations of fish have been hand the pond that has only received raised by artificial feeding of the min- haphazard treatment will yield poor- nows. A good food formula contains ly and may even be a complete 275 pounds of cooked cornmeal and failure. oatmeal, 200 pounds of bone meal, The time of harvest will depend and 400 pounds of clam meal. The upon the size of fish needed by the fish should be fed all of this that they dealer, the species of fish being raised, will clean up in two hours. An excess the method of propagation, and the over this amount will pollute the pond method of harvesting the fish. If the and endanger the oxygen supply. dealer needs crappie bait, he will be Weed Control able to. harvest his fish by midsum- The control of aquatic vegetation mer, but if he has to have pike size is an important problem for the man minnows, he cannot expect to harvest propagating minnows. The weeds in the pond until late in the summer. a pond must be kept in check be- Fathead minnows require three cause they not only use up valuable months to become 2 inches in length fertility in a form that is not useful and in some ponds will not become to the minnows for food but their bait size until the second year. Gol- presence greatly increases the seining den shiners may be M inches in three difficulties. It is best to select a pond months but they are too delicate to that is fairly free of weeds and then seine at that time of summer. In to operate so they never become Michigan, shiners have been success- established. Heavy fertilization early fully taken during hot weather with in the season will produce such a a baited dropnet. The net is made heavy bloom that the rooted plants of cheesecloth and is handled very will be shaded out. In ponds where carefully so that the fish will not be weeds have become established, the injured. Suckers grow to bait size in weed killer 2-4-D offers the best con- a very short time but unless the trol. amount of food they receive is re- Harvesting the Pond duced, they soon get too large for The size of harvest of minnows bait. from the pond will depend upon how-ow The number of minnows that can MINNOW PONDS 11 be produced in a pond depends on a have suitable bait sizes throughout large number of factors that will be the season. Golden shiners should be discussed fully in the third article of raised for spring and fall bait where this series. they are easy to handle. This, of Practical Operation course, will require one pond deep During June of 1947, pike-sized enough to over-winter the fish. Suck- minnows had a wholesale value of ers grow fast and are hardy enough $5.00 per gallon. All considerations to be used for bait during the warm concerning the propagation of min- summer months. nows must revolve around that figure. At the present time this plan seems As long as minnows are that cheap, to offer a sound method of operation the most practical method of raising that will develop into a profitable them is in small, natural ponds that business. Any dealer or resort owner can be leased for a reasonable sum. considering the establishment of a These ponds should be fertile enough minnow hatchery must realize that so that little or no fertilization is while the raising of minnows may pay needed. Those located in or near the operator fair wages, he cannot barnyards receive sufficient low cost expect to get rich quick. Success (as fertilization from the surface runoff. in all fields) depends on a sound Over most of Minnesota, the dealer knowledge of the fundamentals and will find it necessary to raise at least a willingness to learn the best methods two species of minnows in order to by experience.

•

FISH BREEDING During the early days of European carp farming, much time and effort were expended in selecting brood stock from the native fish in such a way as to produce a fast-growing and attractive fish. This line of research pro- duced some excellent strains such as the mirror and leather carp. Similar in- vestigations may be necessary in Minnesota because most minnows do not get to pike bait size in one season and must be held over winter at consider- able expense. Attempts have been made to find a minnow that will grow to bait size in time for sale the first season, but the results are not satisfactory. By selective breeding, however, it may be possible to develop a rapid-growing minnow that is not too large for bait when full grown. BUFFALO FISH

DOGFISH or BOWFIN

1§AUDMINNOW

GOLD FISH

MINNOW IDENTIFICATION CHART DORD Al TAIL OR CAUDAL FRI / ii

aar be I

A na Pcct o rd I Fin NIT; ic Fin "' MIRROR CARP

COMMON SUCKER

GOLDEN SHINER

MINNOW IDENTIFICATION CHART A pond may produce 180,000 minnows per acre Minnesota Minnow Production

During 1946, 53 private hatcheries ers, 21 per cent suckers, and 18 per were producing minnows in Minne- cent fatheads. A 24 per cent produc- sota ponds that covered approxi- tion reported for chubs is probably a mately 735 acres. All fish hatcheries misleading figure. Creek chubs are are licensed by the Minnesota Game difficult and expensive to raise in and Fish Division and are required ponds so most of the chubs reported to furnish a report of their were probably only held in operations at the end of each Min now the pond while they put on season. Complete 1946 re- Propa gallon more growth. Also, many of ports were received from 30 the chubs may have been of the hatcheries represent- • • • dace that are more easily ing the production from 587 Number Three propagated. Table 1 pre- acres of ponds. sents the total production of A summary of the reports shows each species of minnow. that 8,690,890 minnows were raised The Fish Propagation Unit pro- at an average production rate of vides the private hatcheries with 14,805 per acre. The actual total sucker eggs at the rate of 40,000 per yield was much higher but there is acre. The figure represents an equit- no way of arriving at the exact figure. able distribution of the supply and is The reports estimate that 4,089,300 not a recommended stocking rate. minnows were still in the ponds at Thirteen of the hatcheries reported the end of the season but there is no the number of eggs they received record of the stock on hand at the from the state and the number of bait beginning of the season. The produc- size minnows that were obtained from tion in these ponds, however, is very the plantings. These dealers planted low when compared with the 200,000 11,229,820 eggs and harvested per acre that have been raised in 598,240 sucker minnows. Therefore, Michigan. only 5.3 per cent of the eggs devel- While 19 of the hatcheries raised oped into minnows. When the re- suckers and only ten raised golden ports of the six hatcheries that had shiners and fatheads, 27 per cent of complete failures in their sucker the total production was golden shin- ponds are removed from the tabula- 14 MINNESOTA MINNOW PRODUCTION 15

TABLE 1— Minnow Production in Private Ponds — 1946 Season Percentage of Number of hatcheries Species of Minnows Number raised Total Production raising each species Golden shiner ...... 2,346,200 27.0 10 Common sucker ...... 1,791,940 20.6 19 Fathead minnow ...... 1,597,550 18.4 10 "Chub" ...... 2,079,500 23.9 7 Redbelly dace ...... 62,000 0.7 2 Mudminnow ...... 601,200 6.9 4 Brassy minnow ...... 212,500 2.4 1 Total sold ...... 8,690,890 Minnows held over ..... 4,089,300

tion, the survival rate rises to 9.6 per ing time, and an over-abundance of cent which is close to that obtained aquatic insects are the three most im- in other states under similar methods. portant factors. When the sucker eggs are placed The following recommendations for in a tray staked up off of the pond the raising of suckers in ponds are bottom, a higher survival rate is ob- made with the hope of eliminating tained. The sides and bottom of the some of the losses. First, the eggs tray must be of fine enough mesh so should be placed in trays and feath- the fry will not fall through when ered daily until all have hatched. Any first hatched, but the top must be dead eggs should be removed prompt- coarse enough to allow the advanced ly. For the 1947 season, the Fish fry to swim out. The highest surviv- Propagation Unit has taken a step to al, however, is obtained when the help eliminate the early losses by sup- eggs are allowed to develop in the plying the dealers with advanced fry hatchery and the fish are stocked as instead of eyed eggs. advanced fry. Most sucker ponds should be fer- A number of dealers have reported tilized at least two weeks before the the complete failure of many sucker stocking date with 500 pounds of ponds. The Fisheries Research Unit barnyard manure per acre. The easi- has not been notified of these failures est method of application is to spread often enough or soon enough to be it on the ice during the winter. Early able to determine the causes. The fertilization will produce a heavy Unit would greatly appreciate the bloom by the time the sucker fry are chance to study the problem in de- ready to feed on the microscopic ani- tail. The few failures that have been mals. When the fry reach this stage, observed indicate that lack of egg the food must be available or they trays, lack of food for fry at hatch- will die in a very short time. The Top photo—Seining a minnow pond. . Below—Weighing fish in a seining well of an artificial pond. MINNESOTA DEPARTMENT OF CONSERVATION 17 bloom is maintained through the sea- greatly understocked and that the 350 son by periodic applications of, com- adult fish had produced all of the mercial fertilizer. young possible. The average number During 1946, the Fish Propagation of fish produced by each female was Unit operated some experimental min- 650. As the females in the one-acre now ponds in order to obtain more pond also averaged 650 young, it is detailed information on the subject. apparent that the extra space and the The 12 ponds, formerly used to raise excess of food in the five-acre pond game fish, covered 26.5 acres and had no effect on the total number of produced 554,533 minnows for an fish produced. The excess of food average production of 20,918 per showed in the size of the fish at time acre. The heaviest yield obtained was of harvest. In the fertilized pond, 46 180,018 bluntnose minnows per acre percent of the population averaged from a pond at Detroit Lakes. Mud 21/2 to 31/2 inches total length, while puppies and salamanders consumed in the unfertilized pond, only 16 per the entire fish population at two cent of the fish reached those sizes. ponds and game fish in other ponds Fish in the fertile pond grew to 31/2 greatly reduced the total yield of inches in 11 weeks while the fish in minnows. the poorer pond required 16 weeks." The production figures of the state Two ponds at St. Paul demonstrate and private ponds are presented here the effect of stocking and fertilization in order to show that the yield of a on pond yield: (Quotation from "Prop- minnow pond may vary from zero to agation of Minnows and Other Bait over 180,000 fish per acre depending Species".) on the conditions in the pond and the "A five-acre pond stocked with 350 skill of the operator. Whether the golden shiners (70 per acre) was fer- pond produces at maximum capacity tilized with 4,650 pounds of commer- or at less may be the difference be- cial fertilizer and 450 pounds of dried tween financial success and failure. sheep manure. An unfertilized one- The propagation of minnows is not a acre pond was stocked with 200 gol- simple job of stocking fish and reap- den shiners. This pond received some ing harvest in the fall. In order to be fertilization from pasture drainage. successful, the hatchery operator must The fertilized pond had a total yield become acquainted with the habits of 421 pounds of fish which is 85.6 and requirements of the fish he is pounds per acre, while the one-acre raising and must be willing to learn pond produced 245 pounds. This in- by experiment as he goes along. dicates that the five-acre pond was There is no easy way. Cutting down minnow losses

Handling and Holding of Minnows

Minnesota bait dealers are of- A seine full of fish should never be ten troubled with a heavy loss pulled up on shore but should be of minnows in holding tanks. bagged loosely and floated to deeper Studies by the Fisheries Research water for sorting into floating live Unit of the Division of Game and boxes. When the fish are being trans- Fish show that most losses result from ferred to the truck tank, neither the injury to fish during seining, dip nets nor the carrying con- shock caused by improper Min now tainers should be overloaded. the tempering, suffocation from Propa gation "Soft" minnows, like inadequate aeration or tem- golden shiner, should never perature control in holding be seined during hot weather and transporting tanks, and Number Four because the mortality is too the disease that abounds in high. They can be harvested unclean tanks over-crowded with by means of a baited drop net hung minnows. The warm water in lakes with cheese cloth to minimize the in- and the injury from wave action pro- jury. Dip nets used to transfer fish duce a high loss of minnows in live should also be covered with a soft boxes. Some dealers have noticed a material. heavy mortality when stream min- Tempering nows have been held in ponds not Slow tempering is the most import- suited to their needs. For minnows ant method of preventing loss of held in small tanks, prevention of in- minnows. Fish have no means of jury and disease infection are the adapting themselves to rapid changes only practical methods of reducing of temperature. A sudden change of loss. There is no magic formula. more than ten degrees F. will give the fish a fatal shock, though death Careful Seining Methods may not occur for several hours or Prevention of injury must start at even until the next day. As fish can the time of seining. The net should be be hauled better in cold water than landed along a solid bottom when- in warm, it is often necessary to trans- ever possible in order to avoid the fer the minnows from the warm lake roily water that is so injurious to fish. or stream to the cold water of the

18 HANDLING AND HOLDING OF MINNOWS 19 truck without injuring the fish. Safe most of it is due to an accumulation tempering requires at least 20 min- of seining and handling injuries. The utes for each ten degree change in ill effects of rapid tempering will be- temperature. A small diameter syphon come apparent by the time the fish hose will mix these waters at a gradu- are transferred to the holding tanks. al rate, but a thermometer should Since the minnows will remain in the be used to determine the differences holding tanks for a number of days, of temperature. the tanks should be operated so as to minimize injury and disease infesta- Transportation Minnows will stand the strain of tions. transportation best when the hauling The holding tanks should be equipment is carefully designed. The smooth on the inside so the fish will tank should be of sufficient size to not lose scales when rubbing against handle the number of minnows to be the sides and to facilitate cleaning carried, and the inside should be and sterilization operations. The aera- smooth enough so that the fish will tion system must maintain at least not suffer injury. The aeration system, three parts of dissolved oxygen per whether oxygen or sprayed water, million parts of water when the tank must supply a minimum of three parts is full of fish, and the tank should be of dissolved oxygen per million parts deep enough so that the fish are not of water when the tank is fully loaded injured by the stream of water from with fish, but a concentration of five the jets. or six parts is preferable. The fish The water for tanks should be fil- are more hardy at low water temper- tered (spring water is filtered by na- atures so the water in the tank should ture). A number of small tanks are be maintained at 65° F. or lower, es- more desirable than one large one. pecially when the fish are hauled long Diseases can be controlled better be- distances. Missouri minnow dealers cause fewer fish are held in one place often haul fish 1,000 miles in truck and the turnover is more rapid. The tanks insulated with four inches of tank should be small enough so that cork, which are iced when necessary the entire contents can be sold in along the route. Minnows that have four to six days. No additional fish been "hardened" for 24 hours in cold should be added until the original lot water will stand long hauls much bet- has been disposed of, otherwise, some ter than fish taken directly from warm minnows may remain in the tank for water. several weeks. The longer that fish Holding Tank Operation are held in unnatural conditions, the The greatest loss of minnows will more susceptible they are to fungus be noticed in the holding tank, but disease. When one batch of minnows 20 MINNESOTA DEPARTMENT OF CONSERVATION has been sold, the tank should be pollute the tank and increase the drained, cleaned and thoroughly ster- danger of fish loss. ilized in sodium hypochlorite. The Minnows in holding and transport- ;ides and bottom of the tank should ing tanks are living under very ad- be scrubbed with a solution of one- verse conditions. They have been half pint of bleach (Hilex or Chlo- handled roughly, they have been rox) in 15 gallons of water. The tank crowded, and now they are living must be rinsed until all traces of the without food in water that is entire- bleach are gone before it can be re- ly lacking in natural disease prevent- filled for a new batch of fish. All ives, so even under the best of con- tools and dippers should be soaked ditions they will have a hard time in the hypochlorite solution for sev- keeping alive. The bait dealer can eral hours. keep the loss at a minimum by mak- ing the conditions as favorable as Disease Treatment possible. There is no magic formula Though the methods outlined here that can be used at this time. will keep fungus disease at a mini- mum, there are times when the fish Measuring Minnows will become infected in spite of good There may be considerable loss care. Minnows that are infected or from the common practice of selling have been exposed to fungus disease minnows wholesale by the gallon. can be dipped in a solution of one- This procedure necessitates the meas- eighth ounce of malachite green in uring of minnows in a nearly dry 15 gallons of water for ten seconds. state. It is impossible to imagine This treatment is effective as a pre- that such measuring can be done ventive or as a cure. The solution without injury to the fish. Minnesota loses its strength in 24 hours and hatchery men weigh fish by first fill- should not be saved. All dead and ing a metal basket half full of water, dying fish should be disposed of as weighing the basket and water, and soon as they are noticed. Dead fish then adding the fish and reweighing. floating in the tank are a breeding The difference in weight is the weight grounds for the fungus and, conse- of the fish. By counting the num- quently, aid in its spread. ber of fish in a pound, it is possible Fish that are held for long periods to determine the number of fish sold. of time should be fed daily. Soybean By this method it is possible to whole- meal, finely ground oatmeal, or simi- sale fish by numbers, pounds, or by lar foods can be used. The fish should gallons, allowing eight pounds to the be fed only the food they will clean gallon. There is very little injury to up in 15 minutes. An excess will only the fish during weighing. Know your good minnows Identification Of Undesirable Bait Fishes

Certain fishes, such as the carp, minnows in Minnesota that can be goldfish, and dogfish should never be used for bait. Many are difficult to used for bait because of the chance identify but the following character- that these undesirables will be in- istics can be used to separate the true troduced into new waters to the de- native minnows from other species of triment of game fish. Such accidents fish. have occurred due to the dif- 1. Mouth small but not ficulty in identifying these Min now sucker shaped. fish from the many that are Propa gation 2. No teeth on the jaws. suitable for bait. This sec- 3. Small barbels present at tion is presented as an aid • • the corner of the mouth to those who seine their own Numb er Five in only a few species. minnows in sorting out the 4. Dorsal fin with less that' undesirable species. Characteristics of ten rays. both the useful and the undesirable 5. No spines in any of the fins. species have been presented for com- 6. Scales small. parison. 7. No scales on the head, cheeks, or Two rules that can be followed by gill covers. those uncertain of the minnows they have caught are: There are six other kinds of fish 1. When in doubt, never use a some good and some undesirable, fish with more than ten dorsal rays which are often found in bait min- for bait. now pails. These are common or 2. When in doubt, never dump white sucker, quillback and buffalo- live minnows in any lake but the one fish, goldfish, mudminnow, and dog- from which they were seined. fish or bowfin. Many of the terms used in the iden- The common or white sucker is tification section are not commonly closely related to the minnows and used by most fishermen. The picture can be used for bait. It can be dis- of the mirror carp has been labeled tinguished from other fish by the fol- to show the location of the parts lowing characteristics: mentioned. 1. Mouth sucker-shaped. There are at least 40 species of 2. No teeth on the jaws. 21 29 MINNESOTA DEPARTMENT OF CONSERVATION

3. No scales on the head. tinguish between small carp and min- 4. Fine scales near the head and nows or suckers, many carp are in- coarse ones on the tail. advertently transferred to new lakes 5. Dorsal fin with more than ten and streams. The following will help rays. in the identification of the carp: 6. No spine on the dorsal fin. 1. Mouth small but not sucker- shaped. 7. Anterior rays of the dorsal fin not elongated. 2. No teeth on the jaws. 8. Small specimens have three 3. Two barbels at each corner of large dark blotches on each side of the mouth. the body. 4. Dorsal fin with more than ten While the quillback and buffalofish rays. are members of the sucker family, 5. A toothed-spine on the leading they should not be used for bait be- edge of the dorsal and anal fins. cause of the danger of introducing 6. Scales large except in the scale- them into waters where they would less "leather carp". become a nuisance. The two fish are 7. No scales on the head, cheeks, so similar that it is very difficult to or gill covers. tell the young apart, but the follow- The goldfish is another fish that ing characteristics will distinguish cannot be used for bait in Minne- them from other fish: sota. When released into lakes it los- 1. Mouth sucker-shaped. es its gold color in a few generations 2. No teeth on the jaws. and grows to large size. The fish is 3. No barbels at the corners of as undesirable as the carp. The fol- the mouth. lowing characteristics can be used to 4. Dorsal fin with more than 25 identify the goldfish. rays. 1. Mouth small but not sucker- 5. No spine in the dorsal fin. shaped. 6. Anterior rays of the dorsal fin 2. No teeth on the jaws. much elongated. 3. No barbels at the corners of 7. Scales large. the mouth. 8. No scales on the head. 4. Dorsal fin with more than ten It is illegal to use the carp for bait. rays. This regulation is enforced in an at- 5. A smooth spine at the leading tempt to prevent the entry of carp edge of the dorsal and anal fins. into new lakes where it would live at 6. Scales large. the expense of the native game fishes. 7. No scales on the head, cheeks, As many people are not able to dis- or gill covers. IDENTIFICATION OF UNDESIRABLE BAIT FISHES 23

The western mudminnow can be greatly resembles the mudminnow used as bait though it is not a true should not be used for bait. It can minnow. The following characteris- be distinguished from the mudmin- tics can be used to distinguish it now by the following characteristics: from other fish: 1. Mouth large. 1. Mouth large. 2. Jaws well armed with teeth. 2. Many small teeth on the jaw. 3. No barbels at the corners of 3. No barbels at the corners of the mouth. the mouth. 4. Dorsal fin very long, extending 4. Dorsal fin far back on the body, to the tail. as in northern pike. 5. Young have a dark line along 5. More than ten rays in the dorsal the edge of the dorsal and tail fins. fin. 6. Scales large and oblong. 6. A dark vertical bar at the base 7. Males possess a black spot of the tail. rimmed with yellow at upper base of 7. Scales small and round. the tail fin. 8. Head covered with scales. 8. Head covered with hard bony The dogfish or bowfin which plates but no scales.

PHOTO CREDITS Front and back cover photographs and all others are by the author, John Dobie. Photos of the buffalofish, mudminnow, and mirror carp, on pages 12 and 13, are used through courtesy of University of Minnesota Press. 24 MINNESOTA DEPARTMENT OF CONSERVATION

A HISTORICAL NOTE Although only recently seen in the United States, pond culture is actually one of the oldest agricultural practices in use today. Its genesis, as far as can be discovered, is somewhere in the background of a treatise on agriculture containing a volume on the husbandry of fish ponds written by the mandarin Fanli, a minister of the State of Yu (Cheh-kiang Province) about five cen- turies before Christ. Though it may not have been conspicuous, centralized first in Asia, then in Europe, and not receiving wide attention in the United States until only the last few years, it has gathered around itself a complex and sophisticated methodology. Since that time pond culture has remained a more or less prominent method of winning food. John Neese University of Wisconsin

OVER-WINTERING FISH The over-wintering of minnows in natural ponds is a difficult problem. If the pond is deep enough to prevent a winter kill, it is too deep for economical harvesting. Consequently, many ideas for supplying fish with dissolved oxygen have been tried on shallow ponds. Circulating water and cutting holes for aeration are expensive and are very ineffective. Dr. Greenbank of Michigan has demonstrated that ice free of snow trans- mits enough sunlight for the photosynthetic action of plants and the dissolved oxygen produced as a by-product is sufficient to keep minnows alive. There- fore, the most practical method of supplying fish with dissolved oxygen is to keep the ice free of snow. Owners of small ponds will be able to accomplish this with a scrapper like those used on skating rinks. For large ponds, Dr. Hasler of the University of Wisconsin has recbmmended using a centrifugal pump to spray water over the pond and melt the snow. A more recent idea worked out by John O'Donnell of the Wisconsin Con- servation Department makes use of the heat absorbing power of soot. A light soot covering on a pond has been known to melt 6 inches of snow and 3 inches of ice during 2 cold sunny days. The dissolved oxygen content was raised from 2.4 to over 7 parts per million which is ample for fish life. Suggested Reading

The information presented in this bulletin is of general nature and is pre- sented for those who are mildly interested in the care and raising of minnows. Those considering the propagation of minnows a business will want more detailed information on the methods of propagation and the habits of the different minnow species. The following articles contain important informa- tion and are available at libraries or from the publishers.

1. Some results of the forage fish investigations in Michigan by Gerald P. Cooper, Transactions of the American Fisheries Society, Volume 65, 1935, pp. 132-142. 2. Propagation of minnows and other bait species by John Dobie, 0. L. Meehan, and George Washburn, U. S. Fish & Wildlife Fishery Circular No. 12. 3. Northern fishes by Samuel Eddy and Thaddeus Surber, University Press, Minneapolis, 252 pages, illustrated, revised edition. 4. Treat—think—and be wary, for tomorrow they may die by F. F. Fish, Progres- sive Fish Culturist, No. 39, 1938, pp. 1-9. 5. Minnows of Michigan by Carl L. Hubbs and Gerald P. Cooper, Cranbrook Institute of Science, Bull. No. 8, 1936, pp. 1-95. 6. Facts and comments on raising two common bait minnows by A. D. Hasler, H. P. Thomsen, and John Neess, Wisconsin Conservation Department, Bull. No. 210, 1946. 7. Bait Culturists Guide by T. H. Langlois, Department of Agriculture Bulletin No. 137, 1937, pp. 1-13. 8. Propagation of bait and forage fish by H. C. Markus, U. S. Bureau of Fish- eries Circular No. 28, 1939, pp. 1-19. 9. The role of fertilizers in pondfish production by 0. L. Meehan, Transactions of the American Fisheries Society, Volume 64, 1934, pp. 151-154. 10. Organic materials as fertilizers for fish ponds by E. V. Smith, Transactions of the American Fisheries Society, Volume 72, 1943, pp. 97-102. 11. Fertilizers for increasing the natural food for fish in ponds by H. S. Swingle and E. V. Smith, Transactions of the American Fisheries Society, Volume 68, 1939, pp. 126-135.

12. Pondfish culture by Percy Viosca, Jr., The Pelican Publishing Company, New Orleans, , 1937, 260 pages. 13. Propagation of the creek chub in ponds with artificial raceways by G. N. Washburn, Transactions of the American Fisheries Society, 1947, in press.