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Ashland NFWCO
 Midwest Region
 ***Dedicated To Tribal Aquaculture Programs***
      Fish Jumping
          **March 1994 ~ Volume 7****Coordinator:
                  Frank G. Stone 
                  (715-682-6185) Ext. 12
                  U.S. Fish and
                  Wildlife Service
                  Email: [email protected]** Topics
  of Interest: MTAN ArrowSwim Bladder Inflation in Walleyes
  MTAN ArrowSurface Water Spray, Diet and Phase Feeding
  MTAN ArrowProtecting Genetic Resources
  MTAN ArrowTherapeutic Salt Treatments for Preventing Transport of Zebra Mussels
  MTAN ArrowTrap and Gill Nets
  MTAN ArrowLarval Diet Studies for Lake Sturgeon
  MTAN ArrowDiet Preferences for Lake Sturgeon
  MTAN ArrowPond Liners for Hatchery Rearing Facilities (two reports)  Survey of Swim Bladder Inflation in Walleyes Reared in  Hatchery Production Ponds **By: Greg A. Kindschi and Frederic T. Barrows, U.S. Fish and Wildlife  Service Bozeman  Fish Technology  Center, Bozeman, MT 406-587-9265** Noninflation of swim bladders in intensively reared larval  walleyes has been identified as a problem in culturing this species. Walleyes  inflate their swim bladders somewhere between days 7 and 14 posthatch when they  are reared at a water temperature of 15NC. These physoclistous fish must gulp  atmospheric air to initiate the inflation process. Any factor that prevents  them from gulping air and reaching the air-water interface, will prevent the  initial inflation and the normal development of the swim bladder. Physoclistous  fish will survive in captivity without inflated swim bladders; however, they  are in much poorer condition than fish with normally inflated swim bladders.  Prior to our survey of production facilities, there were no documented cases of  pond-reared walleyes exhibiting uninflated swim bladders. Barrows determined that spraying water on the water surface  in circular rearing tanks can significantly increase swim bladder inflation  rates among larval walleyes compared with rates in unsprayed tanks. The  increase in surface water turbulence may allow fish to gulp air or it may  prevent buildup of a surface film of feed or oil that can inhibit gas exchange. Young walleyes depend on zooplankton as their initial food  source, and zooplankton density is a major factor affecting survival and growth  rate. Walleyes without inflated swim bladders must expend a great deal more  energy to capture prey than fish with inflated bladders, and they are more  susceptible to stress. Consequently, survival of fish lacking an inflated swim  bladder may be reduced, particularly after fish are distributed in the wild. If  pond-reared walleyes without inflated swim bladders are observed frequently,  the probability is high that survival rates and overall fish quality are  suffering. The objective of this study was to determine the extent to which  noninflation of swim bladders occurs among pond-reared walleyes raised at  hatcheries around the USA. **Results and Discussion** We examined 120,064 walleye fingerlings from 188 ponds at 15  facilities in nine states. Only 3.5% (4,229) of the fish examined during the 3  years lacked an inflated swim bladder, but the incidence reached 55.3% in one  pond. Fish with uninflated swim bladders were observed in 101 of the 188 ponds  sampled (53.7%). Walleye fingerlings with inflated swim bladders were longer  and weighed more than walleyes from the same pond with uninflated bladders.  Fingerlings examined had been reared in ponds from 24 to 56 days posthatch.  There seemed to be no relation between size of fish at harvest and the  incidence of swim bladder noninflation in any pond. Walleye with inflated swim  bladders averaged 2.45% body fat, whereas fish lacking an inflated swim bladder  averaged 1.45% body fat. This difference in fat content might have occurred for  two reasons. First, fish lacking an inflated swim bladder may not have been  able to capture as much food as the normal fish and thus were unable to build up  fat stores. Second, fish lacking an inflated swim bladder may have been  capturing as much food as normal fish, but expending so much energy in doing so  that fat stores did not develop as fully. A small percentage (not recorded) of walleyes with uninflated  swim bladders exhibited lordotic (spinal) deformities. Kitajima observed this  anomaly in striped bass and suggested it was a result of the uninflated swim  bladder. We concur with this observation and feel these confounding factors  would impede survival. The stocking of pond-reared walleyes that lack inflated swim  bladders may partially explain why certain year-classes do not survive well  after distribution. Even though only 3.5% of the walleye fingerlings examined  in this survey exhibited uninflated bladders, the problem occurred in over half  of the 188 ponds sampled and at all of the 15 facilities. We feel this  indicates that uninflated walleye swim bladders is a significant abnormality  that warrants further monitoring and evaluation to ensure production of quality  fish. Barrows determined that a water surface spray dramatically improved the  inflation rates of intensively reared walleye fry, and this may prove to be a  method for alleviating uninflation problems in ponds as well. During the swim  bladder inflation period (7-14 days posthatch), if there is no wind, a pond  surface spray of water may help break up the surface film and aid in the  inflation process. Recording other hatchery information relevant to pond  production such as weather, water quality, fertilization rate and type, forage  available, brood-stock origin, egg incubation temperature and period, pond  design, and chemicals used, may all be beneficial in case any of these factors  contributes to swim bladder noninflation. This information was informally  collected during this survey but no relation could be determined between these  and the lack of swim bladder inflation. A simple sampling and diagnostic  procedure when ponds are harvested would identify walleye swim bladder  inflation rates before fish are distributed.  Effects of Surface Water Spray, Diet, and Phase Feeding on  Swim Bladder Inflation, Survival, and Cost of Production of Intensively Reared  Larval Walleyes **By: Frederic T. Barrows, Ronald E. Zitzow, and Greg A.  Kindschi, U.S. Fish and Wildlife Service, Bozeman Fish Technology Center,  Bozeman, MT** Walleye eggs have been collected, incubated, hatched, and  stocked into various waters since the late 1800s. Walleye fingerlings have been  reared with formulated feeds since 1971, and research into the intensive  culture of walleye fry has been conducted since approximately 1973. Efforts to  intensively culture fry with formulated feeds have met with poor survival and  low levels of swim bladder inflation. Greater survival was obtained by Hokanson  and Lien (1986), but practical rearing densities and conditions (i.e.,  formulated feed) were not used. Walleyes must inflate their swim bladders  sometime between days 7 and 15 posthatch, when reared at 70NF; inflation will  not occur later. Walleyes without inflated swim bladders can be identified by  their vigorous swimming and head-up orientations. Even when swim bladder  inflation rates of 57-60% were obtained, survival rates were still less than  10% by day 21. Using a deep cylindrical rearing system, we conducted three  trials in 1991. The objectives of these trials were (1) to determine if a spray  of water onto the surface of the rearing tank would increase swim bladder  inflation, (2) to determine the effect of feeding various commercial larval  feeds on survival and swim bladder inflation, and (3) to determine the effect  of phase feeding-giving first a high-quality starter diet, then a lower cost  commercial or experimental diet-on survival, swim bladder inflation, and  growth. **Results and Discussion** Experiment 1: Surface Spraying A layer of oil and fine feed particles developed on the  water surface of tanks not receiving spray. Spraying water on the surface  prevented this layer from developing. The spray did not affect fish length,  production, or survival. Swim bladder inflation was determined after 30 days on  feed, and the inflation rate therefore was influenced by mortality during that  period. The true inflation rate would be best determined immediately following  the inflation period, approximately day 15. The practical measurement includes  mortality that may or may not be influenced by inflation status. In the present  trial, swim bladder inflation was higher for the fish reared in tanks receiving  spray (98.4%) than for fish in tanks without spray (51.7%). The improvement in  swim bladder inflation when the oil and feed layer on the water surface was  dispersed supports the hypothesis that walleye must gulp air to initially  inflate their bladders. Experiment 2: Diet Comparisons Diet affected the growth and survival of walleye fry. Fry  fed BioKyowa-B were larger and had a higher survival rate (33.1%) than fry fed  EPAC (San Francisco Bay Brand) or Larval AP200 (Zeigler). There was no effect  of diet on swim bladder inflation; fry fed BioKyowa-B or EPAC had 95-100%  bladder inflation rates. Each of the three tanks receiving AP200 were drained  on day 9 posthatch, because only a few fish remained and none were feeding. The  small particle size of AP200 might have been responsible for high mortality due  to poor feed consumption, although some fish were observed with feed in their  gastrointestinal tracts. Diet BioKyowa-B is expensive on a per kilogram basis,  but it is a very effective first feed for walleyes. Experiment 3: Phase Feeding Diets BioKyowa-C and WS9112 (manufactured at Bozeman Fish Technology   Center) were readily  consumed by walleye fry after they had been fed BioKyowa-B for 7 days. Survival  at the end of the 30 day trial was similar for fish fed BioKyowa-B, BioKyowa-C,  or WS9112 during phase 2 (30-33%). There was no difference in final length or  swim bladder inflation among fish on the various diet regimens. A considerable  economic advantage was realized with the phase-feeding technique. Overall feed  cost per fish produced was 76% less for the fish shifted to BioKyowa-C than for  the fish kept on BioKyowa-B throughout the trial. The cost of WS9112 cannot be  calculated because some of the ingredients were manufactured in the laboratory.  We estimate that production-scale costs of WS9112 would be similar to those of  BioKyowa-C. Diet regimen affected the body composition of walleyes. The  fish fed WS9112 in phase 2 had less body protein and more body fat than fish on  the other two diet regimens and they grew less, suggesting an imbalance in the  protein and energy levels of WS9112. However, WS9112 is an open-formula diet  that, with the present manufacturing methods, ingredient choice, and binding  system, adequately supports growth and survival of larval walleyes. We have  tested numerous other laboratory-scale diet manufacturing techniques, and  WS9112 is the only one to support survival of larval walleyes as well as the  BioKyowa-B diet does.  Protecting Genetic Resources of Aquatic Organisms:  Elimination of Stock Transfers **By: David Philipp, John Epifanio, and Martin Jennings** As a follow-up to the "Eggs Apples and Fish"  article MTAN published in our December newsletter, we wanted to provide our  readers with another perspective regarding this issue. The following article  (shortened to conserve space) was published in the December 1993 issue of  Fisheries, a bulletin of the American Fisheries Society. **Issue Definition** The culture and introduction of aquatic organisms have been  used by managers to enhance fisheries throughout North   America for well over 100 years. Introductions can be classified  into three types: (1) introduction of a species into an area in which it  previously did not occur naturally (termed non-native introduction); (2)  introduction of individuals from one stock of a given species into waters  inhabited by another, genetically distinct stock of the same species (termed  stock transfer); and (3) reintroduction of individuals cultured from one stock  into waters inhabited by that same stock (termed genetically compatible introduction).  Throughout this position statement, stock is used as the operational unit of  genetic and management concern. The potential dangers associated with the introduction of  non-native species have become well-recognized by biologists. The genetic  integrity of local stocks, acquired as a result of the evolutionary processes  that lead to differentiation and adaptation, is now at risk. However, if we are  to conserve the biological diversity of our aquatic resources on a long-term  basis, that genetic integrity needs to be protected. **Technical Background** Genetic Resources Genetic variation within a species can be partitioned into  two distinct components: (1) intrastock variability, i.e., among individuals  within a stock; and (2) inter-stock variability, i.e., among stocks. Because  both components of variation are important to the evolutionary process, new  efforts to protect aquatic organisms from actions that would reduce either type  of genetic variation are necessary for the long-term survival of species. Genetic variation among individuals within a stock is the  raw material upon which natural selection acts. Loss of genetic variation  within a stock reduces the adaptive potential of that stock. Risks associated  with a loss of this type increase greatly as a consequence of small effective  population size because of the heightened potential for inbreeding and genetic  drift. Culture and management programs that incorporate genetics theory can  minimize those risks; however, many public and private culture programs still  neglect this important task. Several authors have reviewed the evidence  documenting that ignoring genetic principles can reduce the genetic variability  of hatchery stocks of fish. Genetic variation among stocks represents the evolutionary  product of their becoming genetically tailored to the different environments  they inhabit. That is, fish species generally occur as groups of related, yet  distinct stocks rather than as single, randomly mating panmictic units. Because  local environments vary in physical, chemical, and biological characteristics,  each environment has a unique suite of characteristics that affects a different  selection regime on the organisms that inhabit it. Further, because fitness is  maximized through the process of natural selection, individuals acquire  adaptations that make them better suited to the specific environments they  inhabit. Among diverging stocks, gene combinations that prove  advantageous in each different environment become established, eventually  forming coadapted gene complexes. Disruption of these favorable complexes  results from the interbreeding that commonly follows a stock transfer and can  produce individuals that are less "fit" for the local environment.  This decline in overall fitness, known as outbreeding depression, may increase  among individuals of successive generations. Although natural selection will  act on the novel gene combinations that would occur after introgressive  hybridization, the result of that process is unpredictable. Furthermore,  restoration of fitness to preintroduction levels, even if achieved, may require  many generations, and the coadapted gene complexes that previously existed may  be irretrievable. Stock Concept of Management According to the stock concept of management, a species  typically is comprised of multiple, genetically distinct groups (stocks) that  have diverged from other such groups as a result of temporal, spatial, or  behavioral isolation. Thus, the stock, rather than the species as a whole,  needs to be considered the operational unit of management concern. Although the  identification of all stocks within any single species has yet to be completed,  there is overwhelming evidence to indicate that genetically divergent units  occur within many, if not all, fish species. A consensus on the criteria that define a stock has yet to  be achieved among biologists. However, if the genetic resources of native  species are to be protected, actions to curtail stock transfers cannot wait for  absolute refinement of such criteria, emergence of unequivocal methods for  assessing divergence, or development of more complete data bases. Stocking Procedures Each state, provincial, tribal, and federal government in North America has its own culture system, and many  aquatic organisms are introduced annually into waters within its jurisdiction.  Because so many distinct bodies of water currently receive introductions of  aquatic organisms, donor broodstock often originate from a body of water other  than the one actually receiving the introduction. These activities are usually  conducted to satisfy specific short-term goals, but the longer-term ecological  and genetic consequences of such introductions on recipient stocks have seldom  been considered. Three scenarios illustrate the kinds of problems that can  occur because of unwise stocking practices. First, single hatcheries can serve  expansive geographic regions, as is the case with many federal system  hatcheries, and as a result, recipient stocks are often geographically distant  from the source of the donor broodstock. Second, in times of "need,"  a state, province, or individual facility may trade excess production of one  species to another agency or facility in exchange for individuals of some  different species for which production fell short. Third, many private  hatcheries produce aquatic organisms for an undefined and unregulated private  clientele that may introduce them or permit their escapement into waters  containing wild populations of those same organisms. All three scenarios  represent stock transfers that can have deleterious effects on the genetic  structure of native aquatic organisms. Course of Action Because stocking programs can harm the genetic resources of  native aquatic organisms, the American Fisheries Society urges federal, state,  tribal, and provincial fisheries agencies as well as the private sector to: (1) evaluate current culture and enhancement practices to  develop new management programs that will protect the biodiversity of aquatic  natural resources by eliminating stock transfers within their jurisdiction; (2) eliminate any "trading system" designed to  meet quotas for achieving production goals in which agencies exchange organisms  of different species or stocks resulting in stock transfer; (3) develop more stringent regulations governing the  production, sale, and transport of aquatic organisms by the private sector and  promote the adequate enforcement of those regulations to prevent intentional or  accidental introductions into waters containing native stocks; (4) cooperate in achieving a consensus on the criteria that  define a stock and lead in developing informational data bases that include  assessment of genetic variation among stocks of native sport and non-game  aquatic species; (5) form species-level working groups for all managed  aquatic species that will: a. propose boundaries describing component native stocks and  recommend preferred protocols that relate to introductions,
  b. identify areas that would be designated as genetic  reserves to be specifically managed to prevent contamination from stock  transfers, and
  c. assess management goals and objectives to develop  ecologically and genetically based management plans for each species. (6) develop a public education program to promote public  awareness of the issues involved and public acceptance of the proposed  management strategies.  Effectiveness of Therapeutic Salt Treatments for Preventing  Transport of Zebra Mussels With Hatchery Fish **By: Diane Waller, John Crowther, and Jeff  Rach National  Fisheries Research  Center, La Crosse, WI** The zebra mussel is spreading progressively through the  waterways of North America and threatens major  rivers and inland lakes. One potential mechanism for overland dispersal of the  mussels is the transport of baits and hatchery-reared fishes. The transport of  early life stages of the mussel is of particular concern to hatchery personnel.  The larvae, or veliger, is planktonic and remains suspended in the water column  for several weeks. These early life stages are microscopic and can occur in  high densities. Consequently, large numbers of larval mussels can be  inadvertently transported as veligers with fish and introduced into stocked streams,  lakes, ponds, and other fish-holding facilities. There, the veliger may settle  and metamorphose to a plantigrade mussel. Transported fishes are commonly subjected to a saltwater  treatment to reduce disease and stress related to handling. We determined the  toxicity of therapeutic salt treatments to veligers and juvenile zebra mussels  as part of our study to develop a strategy for killing zebra mussels during  fish transport. **Toxicity of Chloride Salts to Fishes and Zebra Mussels** A recommended therapeutic salt (NaCl) treatment for fishes  is from 0.5 to 1.0% for an indefinite period-during hauling-or a 3% dip  treatment for 10 to 30 min. Using this initial treatment guideline, we  determined the toxicity of selected concentrations of the salts NaCl (1.0 and  2.0%), KCL (0.25, 0.5, and 1.0%), and CaCI2 (1.0 and 2.0%) to fishes and  juvenile zebra mussels in 6, 12, and 24 hour exposures. Test fish (48 to 56 mm  and 1.2 to 1.4 grams) included rainbow trout, channel catfish and bluegill. Juvenile  zebra mussels measured 2 to 5 mm shell length. Following the exposure period,  organisms were placed in untreated well water for 24 hours to monitor recovery  or latent mortality. Latent mortality commonly occurred in both mussels and  fishes and the final mortality was underestimated without the postexposure  period. The treatments that killed juvenile zebra mussels caused  significant mortality in fishes. Exposures of 12 hours in the highest test  concentrations were necessary to produce greater than 50% mortality of juvenile  mussels. These exposure conditions, however, also produced from 13 to 100%  mortality of fishes. A 24 hour exposure in the highest test concentration was  needed to kill all juvenile zebra mussels in the treatment. Of the three salts tested,  potassium chloride was the most toxic to the mussels; the percent mortalities  of mussels in a 1% solution of salt during 12 (80%) and 24 hour (100%)  exposures were high in KCL, compared with 0% in NaCl and 35 to 68% in CaCl2. **Therapeutic Levels Are Effective Against Early Life Stages  of Zebra Mussels** Following tests with juvenile mussels and fishes, we tested  the effectiveness of treatments that were safe to the three fish species  against veliger and plantigrade mussels. Tests were conducted using the methods  previously described, except that veligers were not held in clean water for 24  hours after exposure. Several treatment schedules in these test conditions killed  veliger and plantigrade stages of the zebra mussels. The mortality rate of  veligers was 100% in several common NaCl treatments including 1% NaCl for 24  hours, 2% NaCl for 1 hour, and 3% for 15 minutes. In addition, all  concentrations and exposures of KCL caused >90% mortality of veligers.  Plantigrade mussels were less sensitive to the salts; however, 1% NaCl and  CaCI2 for 24 hours and 0.25% KCL for 24 hours were effective against the  mussels. **Control Options for Hatcheries Are Limited** Currently, there are no fishery chemicals approved for use  in hatchery facilities against zebra mussels; yet, aquaculturists are  immediately threatened with infestation of their facilities by zebra mussels or  the unintentional dispersal of mussels into stocked lakes and streams. Chlorine  has been the chemical of choice for control of zebra mussels in industrial  settings-it is nonselective, however, and highly toxic to fish. Nonchemical  methods of control (i.e., filtration, acoustics, and thermal shock) may be too  expensive or impractical for general application. Our results indicate that the NaCl treatments presently used  in many hatcheries to reduce transport-related stress and disease will kill  microscopic stages of the zebra mussel. Furthermore, several treatment levels  of potassium chloride and calcium chloride were highly effective against early  life stages. Higher treatment levels of calcium chloride and potassium chloride  were also effective against larger zebra mussels but not without some risk to  fishes. For example, a 2% CaCl2 treatment for 12 hours killed 100% of the  juvenile zebra mussels but also caused 15% mortality of rainbow trout and 100%  mortality of bluegill. Juvenile and adult mussels can also be removed by visual  inspection of tanks and by filtering of the water supply.  Trap and Gill Nets **By: Steve Mortensen, Leech Lake  Tribal Fish Hatchery** Steve Mortensen (Fish hatchery manager at the Leech Lake  Reservation), provided MTAN with the following information regarding the making  of fish collection nets. These devices work well for the capture of wild fish  for broodstock or gametes. MTAN felt that because many Tribal hatchery managers  are also involved with fishery management responsibilities, that they may  benefit from this information. If you would like to have more details about the  cost of these products, contact "Ojibwe Fish and Foods", RR 3 Box  100, Cass Lake, MN 56633, or call 218-335-6341 **Trap Nets** Our trap nets are constructed with a solid steel framework,  so they sink fast and are quick to set. The hoops are made from galvanized  steel and the frames are formed from solid steel rod, welded and then painted  with an enamel primer. Hoops are of a standard 30" diameter. Stock frames  come in two sizes, 30" x 48" and 36" x 60". The inner  winker frames come in 3", 6", or 12" widths. If you have the need  for custom frames we can accommodate your needs. Because of its lower abrasiveness to trapped fish, we stock  a high-quality, knotless delta netting, in 1/4", 3/8"",  1/2", and 3/4" mesh. Standard dimensions for the small mesh is one  throat at 4" diameter. The large mesh nets are double-throated, one at  8" and the other at 6" diameters. The throats and seams on the  smaller mesh are sewn with a triple-stitch industrial surger. The larger ones  are sewn by hand with #12 tarred seine twine. All ties on the outside framework  are made with #18 tarred twine to give them extra durability. Leads are a standard 4' deep by 40' or 50' long. They are  tied in 4" spacings on 5/16" black twisted polypropylene at top and  bottom. Float line has 2" x 1 1/2" PVC sponge floats every 2', and  weight line has 1" lead balls every other tie. Float line and lead line  are in stock and available on request. **Gill Nets** Our gill nets are made from your choice of top-quality  multifilament or monofilament nylon gill netting. Our nets are made to stay  limp, but deliver extra strength and durability. The mono nets, while not as  flexible, are great in clear water. All nets are tied tightly at the top line on #6 tubular  braided polypropylene, with 1 1/4" x 5" hard plastic floats every 6',  and on the bottom line we use 1/4" 30-lb. leadcore line. Lead inserts or  lead balls are available on request. For hanging, #12 tarred nylon seine twine  is used with an 8" tie spacing. Multi-panel experimental nets are available on request. We  carry, in the multifilament, 1/2" through 2", 2 3/4", and  3" mesh, and in the monofilament, 1 3/4", 2", and 2 3/4"  mesh. Our standard gill net is 6" deep, but other depths are available. We  also now offer 3' x 100' personal gill nets. Seines and Holding Boxes Our seines are made from the same top-quality, knotless  delta mesh found in our trap nets, in 1/4", 3/8", 1/2", and  3/4" mesh sizes. We also stock 1/8" and 3/16" square mesh. Each  seine is tied at the top on 5/16" black polypropylene, with 2" x 1  1/2" PVC sponge floats every foot. For the bottom we offer either a  9-strand mud line or a weighted line. All are tied every 4" with #12  tarred twine and are hung to bag properly. Our holding boxes have triple-stitched seams sewn on our  industrial surger, and are bordered at the top with black polypropylene with  2" galvanized rings tied at the corners. Floating boxes are available on  request.  Larval Diet Studies In Rearing of Lake Sturgeon  For Restoration **By: Martin N. Dilauro, William F. Krise, National Fishery  Research and Development Laboratory, National Biological Survey, Wellsboro, PA.  and Kofi Fynn-Aikins, Tunison Laboratory of Fish Nutrition, National Biological  Survey, Cortland, NY.** A 60-day intensive culture experiment was conducted to  ascertain diet-related differences in fish growth and survival in work  supporting lake sturgeon restoration efforts. Lake  sturgeon first-feeding fry were presented five different artificial diets which  were fed in combination with brine shrimp (live food). These artificial dry  diets were BioKyowa, Biodiet, Tunison, ASD, and SD-9. A sixth separate brine  shrimp-only treatment represented the control. The fry were reared at 16.0 C +  0.7 C in 95 L tanks. Tanks were stocked with 9 fish per L and the fish were  exposed to daily light equivalent to that of natural daylight for the date and  region, with weekly adjustments. The BioKyowa/live food treatment fished to  daily light equivalent to exhibited the highest survival (67.4%), while those  in the SD-9/live food group produced the lowest survival (58.3%), however,  these differences were not significant (P < 0.05). The live food treatment  fish exhibited significantly greater mean length (60.4 m) with BioKyowa/live  diet group indicating the lowest (44.2 mm). The mean weight of the live food  treatment was significantly greater than all other treatments (0.74 g), while  the Biodiet exhibited lowest mean weight (0.37g). Of the treatments tested, the  live food treatment appears to be the diet of choice for first-feeding lake  sturgeon.  Diet Preferences and Growth of Cultured Juvenile Lake Sturgeon **By: William F. Krise, Martin N. Dilauro, National Fishery  Research and Development Laboratory, National Biological Survey, Wellsboro, PA.  and Kofi Fynn-Aikins, Tunison Laboratory of Fish Nutrition, Cortland, NY.  and Frederic T. Barrows, Bozeman Fish Technology  Center, Bozeman MT.** Two 30-day studies, of method for conversion from brine  shrimp to dry diet and diet preference of lake sturgeon 2 month old juveniles,  were conducted to measure differences in diet effectiveness and fish survival.  In the first study, lake sturgeon were weaned from brine shrimp to a dry diet  by reducing the brine shrimp ration 60% over two weeks, then feeding only the  dry diet. The dry diets tested were ASD salmon diet, SD9 trout diet, Biodiet,  BioKyowa and a semi-purified diet. Fish kept on a control diet of 100% brine  shrimp had the highest survival (98%), followed by those fed ASD salmon diet  (69%), then those fed BioKyowa (62%), those fed SD9 (53%), semi-purified diet  (49%), and Biodiet (44%). Fish fed ASD, brine shrimp or SD9 were largest (72-74  mm length), while fish fed other diets averaged 57-59 mm. Condition factor was  lowest for fish fed brine shrimp (0.287), lower than those fed dry diets  (0.300-0.350). Fish fed ASD and SD9 diets were heavier (1.28 and 1.25 g,  respectively) than fish on other dry diets (0.66 to 0.72 g each). In the second  study, fish previously fed only brine shrimp were converted directly to the  diets listed above, plus sturgeon starter #9316. Survival was greatest for fish  fed sturgeon starter #9316 (29%) followed by those fed BioKyowa (15%). Survival  of fish fed other diets was < 10%, and included 0% survival in the  semi-purified diet and SD9 fed groups. Fish fed the #9316 diet averaged 81 mm  and 1.7 g, while those fed BioKyowa averaged 74 mm and 1.4 g. It appears that  feeding brine shrimp to lake sturgeon enhances early survival and allows for a  gradual weaning to dry diets. Benefits of the brine shrimp diet on growth are  lost after about two months of feeding.  Selecting the Appropriate Geomembrane Can Enhance Breeding,  Reduce Cost for Fish Hatcheries **By: Brian McKeown, GSI Geo-Synthetics, Inc., 428 N. Pewaukee Road Waukesha, WI 53188 1-800-444-5523** In the December 1993 issue of the MTAN, we promised our  readers two additional perspectives regarding applications of plastic pond  liners. MTAN hopes that the two articles which follow will not only help you  better understand the different liners that are available, but also provide you  with a source of different manufactures which produce and install this product. In Wisconsin,  lined fish hatchery ponds must be able to withstand a variety of  conditions-frigid winter temperatures and accumulations of snow and ice;  blistering summer heat and continuous exposure to damaging UV radiation, and  different soil and sub-grade characteristics. At the same time, hatchery  operators are looking for products that can enhance breeding and simplify  maintenance. Many hatchery operators are using geomembranes as  containment liners for their ponds. Geomembranes can withstand abusive climatic  conditions and eliminate problems with mud bottoms resulting in better breeding  conditions. There are several basic liner materials that offer various  advantages for fish hatcheries. It is extremely important to use materials that  will meet your specific site characteristics. For a fish hatchery in northern Wisconsin, selecting a  more suitable liner material saved the Fish and Wildlife Department more than  $100,000. Knowing the features and advantages of the different geomembranes can  help you make the right choice. Following are descriptions of various liner  materials offered in industrial and fish-grades. Polyvinyl Chloride (PVC)-is a highly flexible membrane that  withstands uneven surface contours and shifting of subgrades. These qualities  minimize leakage potential, which is why PVC is used as a containment liner.  The material works well under frigid or sub-tropical temperatures, and is  available in standard grade and UV-stabilized material. It comes in thicknesses  from 10 to 60 mm. High Density Polyethylene (HDPE)-is specified for hazardous  waste landfills and other applications where the liner comes into contact with  various chemicals. This liner material offers excellent tensile strength and  resistance to tears. it is also highly resistant to the damaging effects of UV  radiation. It is available in thicknesses from 40 to 100 mm. Very low Density Polyethylene (VLDPE)-is flexible and used  in situations where the membrane must conform to varying ground contours or  shifting and settling subgrades. The material has good resistance to punctures  and stresses, but does not have the overall tensile strength of HDPE and is not  recommended for exposed applications. It is available in thicknesses from 40 to  100 mm. Coex Seal-is a relatively new product, having been on the  market for only a few years. Coex Seal is a coextruded geomembrane containing  VLDPE layered between HDPE. The VLDPE provides 60% of total composition and  each HDPE layer is about 20% of the total thickness. This liner combines the  most desirable properties of HDPE and VLDPE, to offer optimum strength,  flexibility and resistance to UV. It is available in 40, 60, 80 or 100 mm  thicknesses. **Fish Hatchery Case Stud** The Wisconsin Department of Natural Resources needed to  construct seven new ponds and re-line five existing ponds at a fish hatchery in  northern Wisconsin.  The liner would be exposed to sunlight and needed a life expectancy of 20  years. Originally, 650,000 square feet of VLDPE liner was specified  in the bid for the project. Previous tests on VLDPE showed that it would not  provide adequate durability, and UV resistance; the needed characteristics for  this application. Working with the general contractor, GSI requested the  opportunity to modify the specification. Based on the characteristics, we felt  Coex Seal, (manufactured by National Seal Corporation), would be the optimum  choice for the job because of its flexibility and resistance to UV rays. Switching to the Coex Seal geomembrane also reduced the  liner costs significantly as more than $100,000 was saved on the project. In  addition to providing the liner, GSI installed and field welded the liner  panels. With Coex Seal, the VLDPE core offers added flexibility for greater  contact with the soil, while the HDPE exterior provides the UV resistance. This  makes the installation more efficient and economical. GSI also conducted performance and quality control testing  throughout the project. The seams must be as strong as, if not stronger than,  the liner material, to withstand the stress of water pressure, shifts in the  soil and other conditions. We test every inch of the seams to help ensure that  there are no leaks. To date, seven of the twelve fish hatchery ponds have been  completed. The last five will be lined in the spring of 1994. Coex Seal has been used in a variety of applications, but  this was the first time it was used to line fish breeding ponds. We think  you'll see Coex Seal being used more and more for fish hatcheries because it  has durability to withstand the elements, flexibility, for ease of  installation, and could even reduce overall liner costs.  Flexible Membrane Liners for Fish Hatcheries **By: Janice Hall, Technical Services Manager, JPS  Elastomerics Corp. Environmental Products Division, Northampton, MA 01060, 1-413-586-8750** The days of traditional aquaculture have almost faded  completely: when fish hatcheries were comprised of earthen ponds; when facility  operators labored over drying and reshaping ponds after cleaning them; and when  30 to 35 percent yields were considered good. The industry is in the midst of a revolutionary change that  will take hatcheries into the 21st century. The change, driven by the simple  installation of liners on pond basins, is environmentally friendly, makes good  economic sense, and is easy to install. **Geomembrane Lining Systems** The two most commonly specified lining systems utilize  geomembranes based on two different--and each in their own right, highly  successful--polymers: DuPont's Hypalon7 cholorosulfonated polyethylene (CSPE or  CSM), and Himont Advanced Polymers' Polypropylene. The largest and most recent JPS aquaculture installation is  the Dundee Fish Hatchery in Wichita    Falls, Texas, and is  the largest in the state. The Texas Parks & Wildlife Department specified  flexible liners on 73 of Dundee's 99  warm-water ponds totaling 59.5 acres. This was undertaken with the objective of  combating bacterial contamination, to which unlined ponds are very susceptible.  Bacteria can emanate from the basin of an earthen pond and combine with  existing bacteria in the water, creating a greater risk of disease and a  correspondingly lower fish yield. Testing had shown that ponds with liners have less bacterial  build-up from uneaten food and fish waste because they are easier to clean and  maintain. The healthy growth and development of fingerlings is dependent upon a  clean environment which will ultimately result in a higher yield. The high  pressure hoses used to clean a pond work best on the smoother surface of a  synthetic liner, thus providing the cleanest environment possible in the least  amount of time. A liner system also helps the pond maintain its shape by  reducing silting and erosion problems. **Geomembrane Construction & Properties** JPS Aquaculture Liners are typically reinforced with a 10 x  10, 1000 denier polyester scrim for increased tear and puncture resistance. At  the same time, they are flexible enough to easily conform to irregularities in  the pond basins. Both Hypalon and Polypropylene-based liners are NSF-61  approved. The JPS Polypropylene Liner has the added advantage of having a  somewhat rougher surface than other geomembranes, providing better footing for  workers when they clean the drained ponds with high pressure hoses. The membrane is manufactured in 76.5-inch rolls, which are  then prefabricated into large panels of up to 100 x 250 feet in size. These  factory seams are made using a variety of dielectric, thermal, or chemical  fusion seaming methods, depending on the fabricator. The large panels are then  shipped to the pond site, where they are stretched out and final field seams  made to create the finished liner. Hypalon-based geomembranes are field seamed  using a chemical fusion method. Polypropylene liners can be field seamed using  thermal welders (wedge or hot-air). The membrane is typically anchored around  the perimeter using a berm at the top of the side slopes. Both Hypalon and Polypropylene membrane liners have  excellent coefficient of expansion and contraction, so they lay flat after  installation preventing fish loss in folds and wrinkles. In addition, liners  made from these two polymeric materials will not stress crack. Once the pond is lined, the membrane may be covered with  earth or left exposed. Hypalon and Polypropylene liners exhibit outstanding  resistance to ultraviolet radiation and harsh weather, making them ideal for  exposed applications. In aquaculture applications, leaving the membrane exposed  makes cleaning much easier. **Flexible Membrane Liners and the Future** The future of fish farming was highlighted in the industry  publication, World Aquaculture, when it cited an average annual increase of  13.6 percent from 1984 to 1990, and an additional increase of 5 percent per  year expected through the year 2000. Production is anticipated to be 20 million  tons by that time. These figures are evidence of the continuing need to educate  hatchery operators to the production economies of this relatively new  technology to the growing aquaculture industry, namely flexible membrane lining  systems. {A note from the MTAN} A listing of successful JPS liner installations  is available through JPS or the MTAN.  **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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