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Ashland NFWCO
 Midwest Region
 ***Dedicated To Tribal Aquaculture Programs***
      Fish Jumping
          **December 1993 ~ Volume 6****Coordinator:
                  Frank G. Stone 
                  (715-682-6185) Ext. 12
                  U.S. Fish and
                  Wildlife Service
                  Email: [email protected]** Topics
  of Interest: MTAN ArrowIntensive Culture Techniques For Lake Whitefish
  MTAN ArrowAlternative Methods For Anesthetizing Fish
  MTAN ArrowEggs, Apples and Fish
  MTAN ArrowApplications For Synthetic Liners In Fish Hatchery Rearing Ponds
  MTAN ArrowPlastic Pond Liners At Lac du Flambeau
  MTAN ArrowWisconsin Aquaculture Advisory Council  Intensive Culture Techniques For Lake Whitefish **By: Steve Mortensen and John Ringle, Leech Lake  Reservation Tribal Hatchery, Division of Resources Management** The interest in intensive culture of lake whitefish for  stocking and as an aquaculture species has increased dramatically over the last  10 years. This interest, along with some prodding from MTAN, has resulted in  the following outline of the techniques we use to rear whitefish in our  hatchery. The lake whitefish is not a particularly easy species to rear, and  when we started almost 10 years ago our success was rather dismal. Refinements  in rearing techniques, proper rearing conditions and better feed now make it  possible to rear these fish on almost a routine basis. **Egg collection** All of our eggs are collected from wild broodstock. Gametes  from enough broodstock (400) should be used to insure genetic variation. The  timing of egg collection varies considerably from location to location,  dependent on water temperature and possibly strain differences. Temperatures in  the 4-6 C range seem to generate the most ripe fish. Our earliest fish spawn in  late October and the latest ones, in a lake only 15 miles away, spawn about 2  weeks later. We get our eggs from commercial fishermen, which is a very easy  and cost-effective means of gathering them. This also gives our fishermen an  opportunity to be directly involved in the stocking effort. Using this method of egg collection we routinely get 60-70%  eye up. This percentage can only be achieved using live fish. Early in the run  when water temperatures are still warm and many of the gill netted fish dead,  percentages will be lower. We have achieved eye up rates of 93% using fish that  hatchery personnel caught, but this was at considerable effort and cost. Eggs are stripped using a dry method of spawning. Eggs from  several females are stripped into a dry pan, milt from 3-4 males is added and  thoroughly mixed before lake water is added to activate the milt. The eggs are  left in milt and water for several minutes and stirred occasionally before  being rinsed in a screen box and allowed to water harden in the lake. Eggs are  placed in a large cooler filled with water and transported back to the  hatchery. **Egg Incubation** Upon arrival at the hatchery the eggs are tempered to  hatchery water. Eggs are incubated in Big Redd incubators, but not hatched in  them. We can adjust the temperature to get the eggs to hatch whenever needed.  The range of temperatures that will give you high percent hatch is from 4-7.5  C. There is an excellent paper on the effects of temperature on whitefish hatch  by L. T. Brooke in Trans. Am. Fish. Soc., 1975, No.3, pp 555-559. Our normal  temperature regime starts out by maintaining the same temperature as the  falling lake temperature until all our eggs are collected. We then set the  temperature to about 50 C and incubate for about a month. We then start  increasing the temperature to time the hatch of the eggs for after January 1.  Our total incubation time is about 70 days, and the total daily temperature  units (DTUS) is about 650. Eggs are treated with formalin (1:600) at 3-day intervals to  prevent fungus problems. Dead eggs are siphoned off as needed throughout  incubation. Once the eggs are ready to hatch we remove them from the Big Redds,  measure out the quantity of eggs we want to hatch, plus about 10% to make up  for eggs that don't hatch, into each rearing tank. The eggs are then placed in  a conventional McDonald jar that is placed directly into the rearing tank. By hatching in this manner we have a fairly accurate idea of  how many fry are in each rearing tank, and we never have to handle the fry,  thus greatly reducing handling mortality. Hatching can also be enhanced by  increasing the water temperature several degrees once the eggs are ready to  hatch. **Rearing** Whitefish are reared in circular tanks initially at a rate  of about 100 fry per gallon. Initial water exchange rate is about 2 (tank) per  hour. Fry do not have to be fed right after hatch, because they are absorbing  their yolk sack. We start feeding about 1 week post-hatch. Water temperature is  set at 12-13 C to stimulate the fry to start feeding. Fry are started on  BioKyowa B-400gm larval fish feed. This is a very high-quality, and expensive  feed, but it is the only feed we have been able to attain a high percentage  fish survival with. Don't waste your time trying to feed brine shrimp nauplii.  The larval feed is fed at a rate of about 10% of body weight (BW) at half hour  intervals 24 hours a day. Tanks are illuminated 24 hours a day. Larval feed is  fed until the fry go through metamorphosis (they get silvery sides at this  stage) at a length of about 18mm. This usually takes about 20-30 days,  depending on temperature. Once the fish have gone through metamorphosis they  can be gradually switched to a high-quality salmon starter feed. We feed this at  about 6% BW. Fish are switched to larger sizes of feed as they grow and percent  of BW fed is decreased. Tank water exchange rates are increased as the fish grow to  maintain a dissolved oxygen level of 6 ppm or greater in the tank drain  standpipe. We have reared fish at densities as high as 7 lbs. per cubic foot  using an oxygen injection system, but do not recommend going over 3 lbs. per  cubic foot for fingerlings. Tanks must be cleaned every day to maintain high  quality rearing conditions for the fish. This also greatly reduces the chance  of disease problems. Salt baths at 2% to 1.0% can be used to reduce stress and  as a pretreatment. The only disease problem we have ever had is bacterial gill  disease. We treated the fish with Chloramine-T at 6.5 ppm for 1 hour. Nitrogen  gas (N2) appears to be a real problem for whitefish so you need to maintain it  below 100% saturation. Packed columns, vacuum degassing or oxygen injection is  usually a must when using ground water. At water temperatures of 13-14 C whitefish will grow almost  an inch a month, and we usually grow them up to 3-4 inches by June 1 when they  are stocked into lakes. We have also reared them to 6-7 inches. They have been  reared to market sizes in other aquaculture facilities. Barring any disasters,  we will get a survival rate of about 75% from feeding fry to stocked fish. We  transport fish in water with a salt concentration of 0.5%. The information provided above is only a general outline of  procedures we use to rear lake whitefish at our facility, but changes and  improvements are made almost every year. Please feel free to contact us if you  have any questions or need further information. Alternative Methods For Anesthetizing Fish During Fin  Clipping Operations **By: Michael   Donofrio Keweenaw   Bay Biologist   Keweenaw Bay  Fish Hatchery** The Great Lakes Fishery Commission recommends that all lake  trout which are stocked into Lake Superior,  must have at least one fin clipped. At the Keweenaw Bay Indian Fish Hatchery,  we will stock lake trout in November and May. During normal inquiries about the  availability of MS-222 to anesthetize our fish (during fin clipping), we were  told that MS-222 could not be permitted without an EPA discharge permit. Since  EPA permits often take a long time to obtain, we felt a need to pursue the  availability and use of other fish anesthetics. Some hatcheries in Wisconsin and possibly  other fisheries professionals, have experimented with the use of seltzer water  as a fish anesthetic. During our work with Jeff Slade (Fishery Biologist for the  U.S. Fish and Wildlife Service), in the summer and fall of 1993, we became  acquainted with seltzer water as an anesthetic. Frank Stone (USFWS) provided us  with a Wisconsin DNR memo on the experimental use of non-MS-222 anesthetics on  fish. After consultation with Frank and review of local availability, we  decided to use Seltzer water without sodium to anesthetize our fish for fin clipping  before stocking into Lake Superior. We planned on anesthetizing approximately 6,700 lake trout  (30 fish/lb. or 5 inch fish) over a 2-3 day period with two people. The trout  were in a 1,600 gallon fiberglass tank inside our hatchery building. We use unfiltered  well water with packed columns for aeration. The water temperature is 7.5 C and  pH is approximately 7.5 units. We purchased Canfield's Seltzer water from local  grocery stores. The ingredients of this water were only triple filtered  carbonated water. There are several kinds of seltzer water on the shelf, but  all others had artificial flavors, colors, and/or preservatives. We also  purchased two 10 gallon tubs to serve as anesthetizing and recovery tanks. We  used two 2"x4" boards across the tanks as a temporary work station.  This work station would hold our 10 gallon tubs, data sheets, dip net,  scissors, stop watch and anesthetizing tub. We then added 1 liter of seltzer  water to create an approximate 1:20 solution. Groups of lake trout (60-300)  were netted and placed in the anesthetic tub, the induction time was recorded.  Then each fish was clipped and moved to a recovery tub. We placed a cover on  the anesthetic tub to prevent the fish from jumping out prior to the induction  time. To better monitor the effects of the test, we waited until each group of  fish were clipped before transferring them from the recovery tub back into the  main rearing tank. The initial induction time for each group of fish was 2  minutes, the 2nd group was 2.5 minutes, and the third from 3 to 3.5 minutes. We  could usually clip four groups of fish for each anesthetic solution. The last  group would usually take 4 minutes for induction. The induction time was  variable for each group and depended on the number of fish in the tank and the  time interval since the seltzer solution was made. Most fish recovered from the  anesthetic within 3 minutes. We tried to make sure the fin clipping procedure  lasted no more than 15 minutes, (from initial netting, until final placement  into the rearing tank). We clipped approximately 1,600 fish the first day, 2,500 the  2nd, and 2,600 the third day. During the fin clipping process, a few fish,  (< 10%) were seen to exhibit hemorrhaging at the base of the ventral fins.  We were concerned that maybe there was too much stress in the anesthetic tank  or too high a concentration of carbon dioxide in the water. However, after fin  clipping all of the fish, we only recorded 3 dead fish after the first day, 1  dead fish after two days, and 0 mortality after three days. We used 13 bottles of seltzer water to anesthetize these  fish at a cost of $0.70/ bottle or $9.10. A bottle of carbon dioxide gas would  be considerably cheaper as long as there was a simple formula to follow for  adding the right amount of gas to a given amount of water. We will consult with  other fishery professionals to decide on anesthetic use for our Spring clipping  of 45,000 lake trout. We will definitely hire temporary help to aid in the  clipping process. The Keweenaw   Bay fisheries program  will soon begin to investigate the possibility of inserting a coded wire  identification tag into each fish we stock from the hatchery. Since other  state, federal, and provincial hatcheries are stocking lake trout into Lake Superior, we would like to evaluate the survival of  the fish we stock. All Keweenaw Bay Indian Community stocked lake trout will go  into lower Keweenaw   Bay. Survival of the fish  will be monitored through sampling of commercial catch and summer small mesh  assessments commencing in 1995. Eggs, Apples and Fish **By: Tim Goeman, Minnesota Department of Natural Resources** Thanks to the watchful eye of Mike Gallinat (Fisheries  Biologist for the Red Cliff Indian Reservation), the following article was  submitted for our MTAN readers. The article was composed by Tim Goeman (MNDNR)  and was taken from a recent issue of the Mainstream newsletter. Mr. Gallinat is  concerned that as natural resource managers, we all need to remember the number  of fish we may stock is NOT as important as determining whether they need to be  stocked in the first place. Mr. Gallintat was also concerned that natural  resource managers not be pressured to stock out large numbers of small, poor  quality fish, in lakes that already have good natural reproduction. This may  lead the sports angler to believe that tribally speared, or commercially netted  lakes, may need a fish stocking program. The fisheries manager watches the irate resort owner drive  away from his office. The last two hours have not been pleasant. The resorter  wanted walleye stocked in his lake. The manager's best efforts at explaining  adequate natural reproduction, exploitation, harvest, year class variability,  and recruitment seemed to fall on deaf ears. Finally, the resorter stormed out  with a threat of going to the Governor. The manager wondered at the lack of  progress fisheries professionals have made in communicating sound fisheries  principles to the fishing public. Meanwhile, in a separate building only 100 yards away, the  assistant fisheries manager has begun his fourth hatchery tour of the afternoon  for school children. The batteries of eggs always intrigue the wide-eyed  youngsters. The egg-take has been good this year. The hatchery is running at  near-full capacity. Soon, millions of fry will emerge. These scenarios are guaranteed to continue until fisheries  professionals begin realistically assessing the long-term costs of the way we  do business. What has the fisheries manager really communicated to his  clientele when the most significant public relations effort of the year is the  hatchery tour? The message conveyed is: 1) That fish come from hatcheries.
  2) That habitat degradation is so severe that naturally  spawning populations are inadequate or no longer exist.
  3) That the long-term health of the fishery resource depends  on hatchery technology. Fisheries professionals are quick to pontificate about the  value of habitat protection , watershed management, and preserving genetic  integrity of fish stocks. But when was the last time a school group was guided on a  tour that emphasized habitat and the importance of this ecological component? It's so easy to give a hatchery tour. It's convenient for  everyone. It always gets rave reviews and it helps give a fisheries program  some visibility. The long-term costs, however, reach far beyond the mere  dollars and cents of a cost-benefit analysis. I am convinced the real cost  shows up years later when the child has taken ownership of his parents' resort,  a poor year of fishing starts cutting into his profits, and he remembers his  third-grade field trip of years earlier. Is it really so amazing that the  resorter will not believe the fishery manager's reasoning for not stocking  fish? Well-managed hatchery and stocking programs do have a place  in fisheries management, but only as they fit within a sound ecological plan  that has fully considered the long-term integrity of the resource. Hatchery and  stocking programs are not an excuse for habitat loss and poor fisheries management.  Such programs merely serve as treatments for symptoms rather than remedies for  the real problems. At least three times during my short fisheries career of  about 15 years, Aldo Leopold's land ethic has emerged in an effort to give new  life to natural resource management. One reason his thoughts are still valid  today is that most people are urban dwellers with little practical appreciation  for natural and wild processes. The fact is, for most people, eggs come from  the dairy case, apples from the produce aisle, and fish from the hatchery. The  fisheries manager can change some of this thinking, if we change the way we do  business. Applications for Synthetic Liners in Fish Hatchery Rearing  Ponds **BY: Timothy A. Duhe Construction Industry, DuPont Polymers  DuPont Bldg. 5066-3, Wilmington,   DE 19898  302-773-2206** **ABSTRACT** In this paper I will present information on synthetic liners  that are on the market today. An increasing number of fish hatcheries are  including flexible membrane liners based on HYPALON Synthetic Rubber in their  hatchery rehabilitation program. We will review some of the technical reasons  why this trend exists. **Introduction** Accessing technology is always a challenge for our engineering  and designing disciplines. Successfully applying that technology can be one of  the most intensive experiences one might have, especially if that technology is  new. We are fortunate today because a large number of major companies have made  major commitments to take existing technology to new industries. This is the  case with synthetic liners in the Aquaculture Industry. In 1930, Wallace Carothers, a young chemist working at Du  Pont, invented the first synthetic rubber, Neoprene. Over half a century later  you can see Neoprene in over 1500 products and the next 100 applications are  right around the corner. Since Neoprene, a large number of other rubbers and  plastics have been introduced to a variety of industries. Several of these are  raw materials for synthetic liners. Synthetic liners have served industries for  over 20 years in applications from radioactive waste to fish rearing ponds. In  most cases you would not use the same liner for both applications. An  evaluation of the expected performance will often help engineers "design  by function". There is no one single liner material that will satisfy all  applications. **Brief History Of Liners** One of the earliest applications of impervious linings is  reported to have occurred over 3,200 years ago in the construction of the Tigris River  embankment lining at Assur. Since then, natural materials have been used in a  variety of engineering applications, but today most countries in the world are  using synthetic flexible membrane liners. Flexible membrane liners have  achieved the status of "Best Available Technology". Natural materials  are being used less frequently as the sole protector of the environment. Natural soils or clays generally have a permeability value  in the range of 1 x 10-7 cm/sec. and only retard the flow of liquids. Synthetic  liners on the other hand are considered to be impermeable because they have  permeability values approaching infinity. (1 x 10-11 cm/sec.) **Synthetic Flexible Membrane Liners** A flexible membrane liner or pond liner can be defined as a  continuous plastic or rubber sheeting used to cover the bottom of ponds, pits,  and lagoons with the purpose of containing liquids and preventing seepage.  Flexible membrane liners are the leading technology for long lasting economical  barriers for such applications. A wide variety of liner materials are being manufactured and  marketed today. These materials vary considerably in physical and chemical  properties, methods of installation, cost and interaction with various  chemicals. The base "polymers" used make the variations even greater  because of differences due to compounding, manufacturing seaming and  installation techniques of suppliers. Choosing a flexible membrane liner  material is no easy task today for many industries, especially those in the  waste containment business. One of the first things to remember is to "design by  function". Project requirements will determine the proper liner material.  Rarely will the lowest priced material be the "best" liner for the  job. Compromises are usually made if price is the major factor rather than  performance. Price should only be a factor when more than one material meets  all your project requirements. Some of the applications where synthetic liners  are being used in the fish hatcheries include: Rearing ponds and race ways.
    Intensive culturing facilities.
    Relining concrete and asphalt ponds.
    Wastewater treatment ponds and settling basins. **Why Use A Synthetic Liner** The use of synthetic liners in fish hatcheries has been  rapidly increasing for several reasons. These include: Prevention of Water Loss. By preventing the loss of water,  hatchery managers have found pH control to be much more consistent. Temperature  control and oxygen balance are also more manageable when the water level in the  rearing ponds are maintained. Disease Control. Some early experiences indicate that  control of diseases is much easier to attain in a synthetically lined pond.  Effective bacteria treatment has been attributed to the elimination of  contaminated soils. A soil layer on the bottom is not necessary and is counter  productive to parasite elimination. We hope to see further research on this  subject in the near future. Automation. Several fish hatcheries have reported 40-60%  cost reductions in harvesting of small fry and fingerlings because of the  elimination of the soil bottom. These synthetic liners are designed to drain  into the kettle area. The slopes are engineered to insure against  "puddling" thus making dipping and seining obsolete. A synthetically  lined pond that is left exposed to the weather (no soil cover) can be harvested  with a minimal amount of labor. **Choosing A Synthetic Liner** Recognizing that there are numerous types of synthetic  lining materials on the market today, let's take a look at the most widely used  materials for lining rearing ponds and similar applications. Without trying to  go down a line and list every liner on the market, let's take a look at it from  a generic approach, a polymer approach. Every material on the market will fit  into one of four generic categories. Each of these generic categories has  strengths and weaknesses and by understanding these you will be better able to  match a liner material with your specific project needs. **What's A Polymer** Polymers include such chemically different compounds such as  plastics, rubbers and even some of the proteins. The word "polymer"  means repetition of structural chemical units, such as linear chains. These  polymer chains can align themselves in different ways. In some cases they  intertwine like strands of spaghetti-amorphous structures. In other situations,  they align themselves in parallel crystalline structures. So called crystalline  polymers are semi crystalline only, for amorphous portions invariably persist  which fill the intervening space between the crystalline chains. The level of  crystallinity or "semi crystallinity" has a marked effect on physical  properties. (An amorphous polymer may be a very viscous liquid in the extreme  state while a highly crystalline polymer may be very hard or rigid). This level  of crystallinity is what physical properties of lining materials ultimately  relate back to. **Four Classifications Of Polymers Used In The Liner Industry** As previously mentioned, all liners on the market today can  be categorized in one of the following generic classifications: 1) Rubber/thermosets (Neoprene, EPDM, Butyl)
  2) Compounded plastics (PVC, CPE)
  3) Crystalline plastics (HDPE)
  4) Thermoplastics elastomers (HYPALON) The types of liner listed next to the classification are  just a handful of lining materials that are on the market, however, these are  the materials that you would most likely see in water containment applications.  Let's take a look at each of the generic classifications! Each of these has  strengths and weaknesses and please remember that there is no single material  that will work in every project. You should become familiar with these advantages  and disadvantages and make your liner decision on which is the best material  based on the technical requirements of a specific project. **Synthetic Rubber/Thermosets** Neoprene, butyl and ethylene propylenediene monomer, EPDM  thermosets were the first generation of liner materials. By definition  rubbers/elastomers are materials which at room temperature can be stretched to  twice its original length and upon immediate release will return with force to  it's original length. Due to difficulty in producing good seams with cured  materials, thermosets are not generally used today in containment applications. **Compounded Plastics - Polyvinyl chloride (PVC) and  Chlorinated polyethylene (CPE):** By definition, thermoplastics are heat formed products that  gain their strength from their crystalline structure. Polyvinyl chloride is a  versatile thermoplastic which can be compounded with materials such as  plasticizers and other modifiers to produce a flexible membrane. You may be  familiar with PVC in its more rigid form such as plastic pipe and siding,  however, compounding plasticizers into the material will produce a very  flexible rubber-like material. There is a wide choice of plasticizers (both the  traditional liquids and polymerics) that can be used in PVC sheeting, depending  upon the application and service conditions under which the PVC membrane will  be used. Carbon black is added to prevent ultraviolet attack of the  PVC polymer. The carbon black causes the absorption of solar energy when left  exposed, raising the temperature to a high level to cause migration of the  plasticizer making the PVC less flexible. Plasticizer loss during service is  the key source of PVC degradation. The effects of plasticizer in fish ponds is  not known. A soil or other suitable cover material used to bury the liner  protects it from ultraviolet exposure and reduces the rate of plasticizer loss. Newer PVC formulations are designed to retard the loss of  plasticizer for longer exposures. CO polymer alloys and nitrile butadiene are  two examples of improved plasticizers. PVC's are generally lower in price and  have good seaming characteristics. PVC is the most widely used compounded  plastic on the market today. Life span is limited and the added expense of a  dirt cover makes PVC less attractive for rearing ponds. Plasticizer migration  is the major concern. **Seaming and Repairing PVC** PVC is prefabricated into large panels and then delivered to  the site for field seaming. Prefabricating the panels provides better quality  control and reduces the amount of field seaming. PVC can be heat welded or  solvent welded in the field. Any repairs that are to be made to a PVC liner can  be done in a similar manner following the manufacturers instructions. **Crystalline Plastic - High density polyethylene (HDPE):** Polyethylene is widely used for liners because of its good  resistance to chemicals and was needed for extremely hazardous waste disposal  sites in spite of other mechanical and physical problems. The properties of  polyethylene are largely dependent upon its crystallinity and its density. In  fact, it is this crystallinity which accounts for almost all of its recognized  problems today. HDPE has a high coefficient of thermal expansion, causing  stress in the seam areas. The polyethylene being used today in the liner market  is generally a medium density polyethylene, but many producers still refer to  it as "HDPE". HDPE polymers do exhibit good resistance to oils, solvents  and permeation by water. Unprotected clear polyethylene degrades readily on  outdoor exposure but the addition of 2-3% of carbon black can produce improved  protection from ultraviolet attack. Polyethylenes for the most part are free of  additives such as plasticizers. Polyethylene membrane liners are made by sheet extrusion  processes. The width of the sheet can be as much as 22 to 34 feet. Thickness is  usually between 40 to 100 mils. These thicker sheets are very stiff in  comparison to the other membranes described in this paper. Thinner sheets are  more difficult to field seam due to temperature sensitivity and are also  punctured easily under impact such as when rocks are dropped on the liner. {A  Note from MTAN} You may want to fence your ponds in to ensure deer will not  puncture holes into the liner. **Seaming and Repairing HDPE** HDPE is supplied to the job site in rolls that are the same  width as it is produced. Because of the stiffness of the HDPE it would be very  difficult to prefabricate panels and then fold them as is done with other  flexible membranes, i.e. HYPALON and PVC. The rolls of HPDE are unrolled at the  job site and each sheet is seamed to the adjacent one using either an extrusion  welding technique or some other type of heat seaming such as a heated wedge,  double wedge etc. Seam integrity is very dependent on operator skill. If using the extrusion welding process, the beaded extrudate  used to cap the overlapping sheets must be of the same resin type as the  original sheeting to assume a homogeneous seam. HDPE cannot be solvent welded. Polyethylene is more difficult to seam, although it appears  easy if you watch the process in the field. If you inspect the seams, most will  look good and you'll walk away satisfied. What you don't see is that the act of  melting the polyethylene during any of the processes has caused a realignment  of the crystals, in effect producing a polymer having different properties  along the seam area than found in the center of the sheet. This melting and  cooling process builds in stresses which can produce cracks in the liner with  time. Also, if repairs are needed on a HDPE liner after the installation crew  has left the site, then all the heavy seaming equipment must be brought back.  Various suppliers of HDPE have placed heavy emphasis on improving seam  methodology, which undoubtedly is to the benefit of the reservoir owner. HDPE is more subject to environmental stress cracking. We  will discuss environmental stress cracking in the "physical  properties" section of this paper. In summary, a strict (QA/QC) Quality Assurance/Quality  Control program is highly recommended. **Thermoplastic Elastomer - HYPALON / Chlorosulfonated  Polyethylene:** HYPALON is made from high density polyethylene but with some  important differences to address previously discussed problems of straight  HDPE. To solve the problems associated with the crystallinity of HDPE, the  chlorine in HYPALON interrupts or reduces the crystallinity and produces an  amorphous, rubbery product. Since the crystallinity is the source of strength  to HDPE, the addition of chlorine has reduced this inherent strength. A small  amount of sulfur is then added to get back to a stronger but much more flexible  liner material. HYPALON is characterized by ozone resistance, ultraviolet  stability, heat resistance and excellent weatherability. Compounded HYPALON has  achieved wide recognition as a sheet membrane for roofs due to its excellent  performance as an exposed membrane. Since 1958, HYPALON has been used in protective applications  such as wire and cable, HYPALON coated fabric such as the Good Year Blimp and  many other demanding applications where weatherability and durability are major  criteria. Membranes based on HYPALON are available in a variety of colors other  than black. Potable water reservoirs use the colorability of HYPALON to enhance  aesthetics while providing the environmental protection to our drinking water.  Compounded HYPALON has no plasticizer and so has good resistance to growth of  mold, mildew, fungus and bacteria. Flexible membranes liners based on HYPALON are available in  industrial and potable grades. The potable grade of HYPALON is approved by the  American Water Works Association for storage of drinking water. Flexible  membrane based on HYPALON are produced by calendaring a coating of HYPALON on  both sides of a polyester scrim. The HYPALON encases the scrim by bonding to  itself through the openings between the fibers. This double encapsulation  avoids possible pinholes that can occur in unreinforced films. The scrim reinforces  the HYPALON and provides dimensional stability, increases tensile and tear  strength and improves properties at elevated temperatures. The most commonly  used scrim is a 10x10x1000D which has 10 counts per inch in both directions. A  membrane with a single ply of scrim is generally used with a total thickness of  36 mils. Scrim reinforced HYPALON is produced in five foot wide  rolls. The rolls are fabricated "in house" under controlled  conditions (without the typical field variables of air temperature, air velocity,  relative humidity, equipment speed, etc.) into larger panels custom sized to  specific site specifications, drastically reducing the number of necessary  field seams. **Seaming and Repairing Hypalon** HYPALON is seamed with solvent cements or with heat. Any  field seaming is usually done with a bodied solvent consisting of 10% HYPALON  compound dissolved in a solvent, which evaporates after bonding leaving the  composition of the seam to be the same as the remainder of the membrane. Any repairs that are to be made to a HYPALON liner can be  made using the manufacturer's instructions with only scissors, brushes, bodied  solvent and a hand roller. Designing With Synthetic Liners - Physical Properties The design process should include full consideration of all  aspects of expected performance. Designing is much more than specifying a liner  based on thickness as is being done more often than not today. A full evaluation of physical performance is recommended to  obtain the most appropriate liner for your individual site. It is not an easy  task to compare reinforced membranes to unreinforced membranes. The following is a review of some physical test data that  can help you specify your liner requirements. A. Strength in Tension - Strength in tension measured in one  direction: HDPE produces a curve with a yield point in the range of 15  to 20 percent elongation. At the yield point it starts to "neck-down"  in a localized area until the polymer chains are highly oriented and they  resist further elongation. As the tensile test continues the adjoining areas  start to neck-down until they are also highly oriented. This process continues  until the test specimen breaks. This performance seems impressive, but the stress-strain  curve does not adequately describe what is happening to the HDPE as it is being  stretched. The high strength indicated by the stress-strain curve is realized  only in the direction the specimen is being stretched. The strength in any  other direction is very poor. For this reason, tear strength and puncture  resistance are also very poor after the HDPE starts to neck-down. This can be  demonstrated by taking a stretched test specimen, placing it on a soft surface  and pushing a ballpoint pen into the surface of the specimen. It will easily  penetrate completely through the membrane where it has been stretched. After it  has been punctured, it can be torn very easily. Scrim-reinforced HYPALON provides a stress-strain curve with  a sharp yield point at about 20 percent elongation when the longitudinal scrim  fibers break. The membrane still provides a continuous barrier of HYPALON, but  the longitudinal strength is now much lower than it was. The useful part of the  stress-strain curve is primarily the part before the fabric break. To compare the strength of HDPE membrane with that of a  scrim-reinforced membrane of HYPALON, the strip tensile method of ASTM D751 was  used. This test uses a 1 inch strip pulled at 12 inches/min. The maximum  strength at yield or a fabric break was measured for each membrane material. At room temperature scrim-reinforced 36 mil HYPALON is  stronger than 60-mil HDPE and is almost as strong as 80-mil HDPE. At 158 F  HYPALON is equivalent to 60-mil HDPE. When elongated at 2 in./min, the 36-mil scrim-reinforced  HYPALON has higher strength than 60-mil HDPE. HYPALON also has significantly  higher elongation at yield compared to HPDE at any thickness. Similar  stress-strain tests were run at a much slower strain rate (.02 in/min) to  simulate the very slow strain rate that occurs when differential settling is  encountered in a pond or landfill. At this slow strain rate, all materials have  lower tensile strength but that of HYPALON is slightly better than 80-mil HPDE. B. Biaxial Strength - Strength in tension measured in two  directions at the same time: Stress imposed on flexible membrane liners in actual service  is often in two directions rather than the one measured by typical  stress-strain test. Special testing equipment is required to obtain this type  of stress-strain data and only limited study has been conducted in this area.  However, in June 1984, Steffen reported the results of his work with a number  of commercial membrane liners (International Conference on Geomembrane in Denver). He found that  HDPE fails at relatively low elongations when stressed in two directions. He  also found that the elongation at failure was dependent on the thickness of the  membrane. Steffen expressed the belief that there was further evidence  supporting the need for a minimum thickness requirement for HDPE membrane  liners of 2.O mm (79 mils). Scrim reinforced HYPALON was not included in the original  work, but has since been tested on the same equipment and by the same test  procedure. HYPALON was found to have a failure elongation of 30.3 percent,  which is 3 times greater than 60 mil HDPE. The higher elongation provided by  HYPALON is very meaningful for liners for ponds or landfills. The stress  applied to the liner by the tons of liquids or solids it supports would far  exceed the strength of any liner if it were not supported by the soil  underneath. To avoid rupture and failure of the liner, it must be able to  accommodate the movement caused by any differential settling of the soil  without exceeding the failure elongation of the liner. The high elongation of  scrim reinforced HYPALON provides a big safety factor compared to HPDE. C. Environmental Stress Cracking: Crystalline and semi-crystalline polymers, such as HDPE, can  develop stress cracks when exposed to certain conditions while under stress.  Some of these conditions include chemicals that only attacked these polymers  when they are under stress. This problem is generally labeled as environmental  stress cracking. HDPE is known to be sensitive to a variety of chemicals of  which the most common types are soaps and detergents. Environmental stress  cracking is receiving a great deal of attention. Several organizations are  researching and trying to explain the cause of this phenomenon. D. Coefficient Of Thermal Expansion: The amount of expansion or contraction that occurs when a  membrane is heated or cooled is expressed as its coefficient of linear thermal  expansion. It is determined by accurately measuring the dimensions of a test  section at two different temperatures and calculating the percent change/degree  F or C. HDPE has a very high coefficient of thermal expansion (.018%/ C). This  means that a liner on a 500 foot berm will expand more than 6 feet on a day  when the temperature starts at 32 F and the black liner gets up to 158 F in the  early afternoon sun. To accommodate this much expansion, the liner develops  large undulations or waves on the berms and exposed side slopes. Besides  providing a poor appearance, this results in severe stress in the region  between the exposed membrane and the membrane that is below the liquid level  which expands very little. This high linear expansion also placed limitations  on when seaming can be done. Seaming on hot sunny days can result in split  seams or the liner lifting away from the corners at the top of the side slopes  as the liner contracts during cooling in the evening. Scrim reinforced HYPALON has a coefficient of linear thermal  expansion of .006%/ C (1/3 that of HDPE). With the greater flexibility of the  HYPALON liner, it can easily accommodate this much expansion without causing  problems. A high coefficient of linear thermal expansion will add tension to  the seam areas causing failed seams. **Private Sector** As the demand for fish as a major food source continues to  increase, intensive culturing is becoming more necessary. Extended life of  ponds as well as water quality are becoming factors that are critical to the  success of fish farming. The ability to control the factors that influence the  health of the fish is being achieved by utilizing the latest available  technology, flexible membrane liners. Flexible membrane liners have also  contributed to the elimination of "off taste" fish. A phenomenon that  has cost some fish farms as much as 80% of their harvest to go to second  quality at second quality prices. **Sport Fish Restoration Program** Thanks to programs such as the sport fish restoration  program, utilizing the latest available technology has become attainable. The  state wildlife and fisheries organizations have been successful in qualifying  fish hatchery rehabilitation as a sport fish restoration program, thus utilizing  the federal funds that are available. Each state has a federal aid contact that  handles compliance to this program. Handbooks are also available from the U. S.  Fish and Wildlife Service that better define the program requirements. **Conclusions** While there are many liner materials to choose from, only  the requirements of the individual project should dictate which material is the  best choice. In buried applications the choice for a liner material varies  greatly. In applications where the liner will be left exposed to the sun in  order to enhance drainage and harvesting then the choices are fewer. Each  material's strengths and weaknesses should be considered. Flexible membrane  liners based on HYPALON synthetic rubber have demonstrated decades of proven  performance. Approval by the American Water Works Association combined with its  excellent weathering properties have made the potable grade of HYPALON  synthetic liners the "best available technology".  Plastic Pond Liners at Lac dU Flambeau **By: Larry Wawronowicz, Fish and Game Director, Lac Du  Flambeau Band, Lac Du Flambeau,   WI** The Lac du Flambeau Fish Culture Program has purchased and  installed 135,746 square feet of plastic liners for six 1/2 acre ponds located  on Highway 47 North and Longs    Point Lane. The liners were purchased from Yunker  Plastics of Lake Geneva, Wisconsin. Over the past several years, seepage in ponds one through  six started to become a problem which was having an negative effect on walleye  fingerling production. The fertilization program was becoming unpredictable and  pumping costs were increasing. Since clay is a very rare commodity in Lac du  Flambeau, Wisconsin,  plastic liners were chosen to seal the ponds. The Lac du Flambeau Fish Culture  Program purchased the plastic liners from Yunker Plastics because they provided  an excellent product within budget and friendly service. The program is always  conscious about supporting businesses located in Wisconsin. The plastic material purchased is described as AW 1616-16A  Black HDPE/LDP woven. Physical characteristics include coating, color, weight,  total thickness, flex abrasion, low temperature bend, tear strength, bursting  strength, tensile strength, hydrostatic resistance, dimensional stability and  carbon black. The plastic material includes carbon black to provide some UV  stabilization, is approximately 20 mils thick, and has 16 x 16 counts per inch  which makes the material strong yet flexible at cold and warm temperatures. The  material reminds me of black strapping tape with strapping going in both  directions or perpendicular to each other. Installation of the liners was easier than anticipated. One  major advantage was that they are in one piece. No in pond seams have to be  welded. Ponds were prepared by removing vegetation, rocks, sticks and other  sharp objects from the pond bottoms and levees. A trench was dug around the  perimeter of each pond with a "witch-ditch" and attachment sites for  the liners around the water supply lines and drain lines were installed. The pond liners, which are folded like an accordion, were  rolled out along the crown of the long levee with a tractor. Approximately 20  people lined up and grabbed the free end of the liner with sticks and on count,  ran down the levee, across the pond bottom, and up the opposite levee. The air  trapped under the liner makes the liner float over the pond causing the liner  to be installed in one quick and easy coordinated motion. If the installers  became uncoordinated and the liner hit the bottom of the pond before everyone  is on the opposite levee, or if the liner had to be repositioned, air had to be  pumped under the liner by simulating the "stadium wave". After the  liner is properly positioned, the ends of the liner are inserted in the trench  in a "J" configuration and dirt from the ditch returned to lock the  liner to the levee. Holes are cut into the liners to accommodate the water  supply and drain lines and then sealed. **For more information on the material, its physical  characteristics, or installation procedures, 
            please call Mr. Brian Yunker of  Yunker Plastics (Yunker Plastics 200 Sheridan Springs Road, 
            Lake Geneva, WI  53147, Phone 414-249-5233).**  Wisconsin Aquaculture Advisory  Council **By: Larry Wawronowicz, Fish and Game Director, Lac Du  Flambeau Band Lac Du Flambeau,   WI** Many of our Wisconsin readers may not know Wisconsin has an Aquaculture Industry  Advisory Council (WAIAC). The purpose of the WAIAC is to: Assist in implementing the Wisconsin Aquaculture Plan. Advise legislators and other interested agencies on how  aquaculture is going to develop in Wisconsin. The Council is chaired by Mr. Bud Sholts and consists of 12  voting council member and non-voting ex-Officio council members. All council  members are industry representatives and ex-Officio members are representatives  from the Department of Natural Resources, the University system and Department  of Agriculture, Trade and Consumer Protection. Currently, the member tribes of the Great Lakes Inter Tribal  Council are being represented by Mr. Dick Hartmann (715-349-2195) of St. Croix and Mr. Larry Wawronowicz (715-588-3303) of Lac  du Flambeau. If your tribe has any ideas, comments, suggestions, information,  or problems in dealing with aquaculture, feel free to contact Mr. Hartmann or  Mr. Wawronowicz. Your tribe's input would be greatly appreciated and required  in order to represent your tribe accurately. WAIAC meetings are held on a  quarterly basis. The meetings are open, so feel free to attend.  **Return
          to MTAN selection pageReturn to Ashland NFWCO home pageReturn to Region 3 U.S. Fish and Wildlife Service** 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.
 
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