**OCT**
               MAY
				Jun11
				Next capture2008
               2009
				2010**3 captures**
           22 Oct 08 - 11 May 09
   Close
       Help


Ashland NFWCO
 Midwest Region
 ***Dedicated To Tribal Aquaculture Programs***
          Fish Jumping
              **September 1998 ~ Volume 25****Coordinator:
Frank G. Stone 
(715-682-6185) Ext. 12
U.S. Fish and
                  Wildlife Service
Email: [email protected]** Topics
  of Interest: MTAN ArrowMatters  of Fish Health
      MTAN ArrowZebra Mussels
      MTAN ArrowMuskrat Control
      MTAN ArrowBird Damage Control
      MTAN ArrowMaximize Your Hatchery's Budget To Train Your Staff  Matters of Fish Health Fish diseases constitute one of the most important problems  and challenges confronting fish culturists. Fish in intensive culture are  continuously affected by environmental fluctuations and management practices  such as handling, crowding, transporting, drug treatments, undernourishment,  fluctuating temperatures, and poor water quality. Fish diseases do not occur as a singly caused event but are  the end result of interactions of the disease, the fish and the environment. All of these factors can impose considerable stress on the  homoeostatic mechanisms of fish rendering them susceptible to a wide variety of  pathogens. Parasites, viruses, and bacteria are all causes for concern to  aquaculturists. Many of these pathogens are easily treatable and are not  transferrable to humans. On the other hand, there are fish diseases that are  not treatable and cause widespread mortality both in the hatchery and wild  fish. Disease also reduces hatchery efficiency and production, which in turn,  increases costs and reduces profit. Another major issue pertaining to fish health is the concern  over the introduction of infectious diseases, particularly those that are not  endemic to the area, through fish culture facilities to wild fish populations.  The impacts of infectious diseases are generally misunderstood or seriously  underestimated, and it is not uncommon to find resistance to their assessment  and control. Many of the fish health programs, guidelines and regulations are  simply regarded as another bureaucratic impediment and cost placed in front of  the aquaculture industry. This attitude is due, in part, to the "old  school of thought" that significant epizootics rarely if ever occur in  wild populations and to the abiding faith that once fish are released into the  wild they will recover. Wild fish stocks can become infected and suffer high  mortalities through the release of pathogens in untreated hatchery effluent or  through the stocking or escapement of diseased fish into aquatic systems. For example, the State of Colorado  stocked hatchery-reared trout known to be infected with whirling disease  (Myxobolus) on a population of wild trout in a major Colorado   river fishery. Result: the wild population was infected and  suffered high mortalities. Three state fish & wildlife officials lost their  jobs for introducing these disease infected fish. A state fish hatchery in Paradise, Utah,  withdraws water from the Little Bear River for culture purposes and discharges  it back into the river. Biologists were made aware of deformed wild fish in the  Little Bear. Upon investigation 8-22 percent of the native population had been  infected by the disease Myxobolus. The source of disease was traced back to the  Paradise Hatchery. In Michigan,  a pathogen-contaminated hatchery discharging into a nearby river infected the  wild fish population in that river. All fish in the hatchery and river were  eradicated to prevent further spreading of the pathogen throughout the  watershed. The state of New York  last year ordered that 43,000 pounds of fish be destroyed from four state  hatcheries because they were infected with whirling disease. This same disease  is also now plaguing state fish hatcheries in Connecticut. All responsible fish hatchery managers should consider fish  diseases a serious potential threat to the health of our public aquatic  resources. Some of the measures we should all employ at our Tribal  facilities relative to fish health include annual diagnostic inspections,  standard disinfection procedures on tanks, raceways and fish hauling trucks,  inter-hatchery fish movement restrictions and requiring a fish health  certificate from any facility conducting a fish/egg transfer.  **What Every Fish Hatchery Worker Should Know about Zebra  Mussels** The zebra mussel is a freshwater clam native to the Caspian  Sea of western Russia.  First discovered in 1988 in the Great Lakes region, it has spread at an  alarming rate throughout the eastern North American continent and has been  reported as far south as New Orleans.  A single mature female zebra mussel can release over a million eggs in a  season. Because of its diverse genetic background, the zebra mussel is highly  adaptable to a wide range of environments. Densities approaching 100,000 ft2 and 10 inches thick have  been reported in industrial water intake pipes. Cost to fishermen and consumers  in the Great Lakes region is estimated to be 5  billion dollars by the year 2000. The greatest physical impact that the zebra mussel will have  on fish farmers is as a macrofouler. Hatcheries, raceways, intensive  recirculating systems and holding facilities will probably sustain most of the  anticipated damage. **Impact On Fish Farmers** Zebra mussels will clog filters, screens, cages and pipes.  Zebra mussels have been identified as the intermediate host for at least one  species of parasitic trematodes which can infect cultured fish species. Zebra  mussels have also been found to be attached to aquatic plants such as coontail,  hydrilla, Naiad and milfoil and have the potential of surviving in mud-bottomed  aquaculture ponds having macrophytes. Because they are highly efficient filter  feeders, dense populations of zebra mussels in ponds could conceivably reduce  primary production such that fry and fingerlings are literally starved to  death. **Preventive Measures** The adage, "An ounce of prevention is worth a pound of  cure" could never be truer when it comes to zebra mussels. Once  established, zebra mussels can be difficult, costly and sometimes impossible to  eradicate. Here are steps you can take to protect your Tribal hatchery  operation: Keep out Contaminated Equipment and Fish Shipments. Zebra  mussels can enter your facility either as microscopic larvae transported in  water, or as adults attached to boat hulls, motors, trailers, harvesting  baskets or catfish holding socks. Strictly prohibiting boats and other  equipment from contaminated waters onto your property can eliminate most  sources of zebra mussels. Allow only shipments of fingerlings and brood stock  from operations which are certified zebra mussel-free. Clean, Dry and Quarantine. Steam clean or immerse in hot  water (140 F) for 3-4 minutes, dry and quarantine all contaminated equipment  that comes on your premises. This includes seines, nets, buckets, hauling tanks  and pumps. Bulky equipment like seines should be spread out in the sun for 3-4  days since adult zebra mussels can live more than a week out of water in warm,  moist areas. Remove Aquatic Weeds. Remove, inspect and properly dispose  of aquatic weeds that inadvertently are carriers into your facility. Don't  allow either of these pests to become established in your ponds. Protect Your Water Supply. Since most surface waters will  eventually be infested by zebra mussels, fish farmers should use ground water  from a well or spring where feasible. Water taken from creeks or rivers should  be filtered using sand filters or buried infiltration beds. In extreme cases, a  constant-flow treatment of chlorine/sodium thiosulphate can be used to treat  contaminated waters. Needless to say, keeping zebra mussels out of your fish  farm will eliminate unnecessary headaches and expenses. **Control Measures** Several non-chemical practices that can help control zebra  mussels at your farm are: Filtration Systems. Filtration is probably the most  effective and economical method for operations that use surface waters. Sand  filter, submerged infiltration beds and in-line filters will eliminate most  stages of the zebra mussel.
      Desiccation. Hatchery ponds are typically drained and  allowed to dry during the off season. This practice will kill all stages of  zebra mussels.
      Heat Treatment. Contaminated equipment can be steam cleaned  or immersed in hot water (140 F) for 3-4 minutes to kill juvenile and adult  zebra mussels.
      Biological Controls. Freshwater drum, blue catfish, redear  sunfish and common carp are all known to feed on indigenous clams. A  polyculture arrangement using one or a combination of these species should be  effective against juvenile and adult zebra mussels.
      Chemical Controls. Several chemical treatments have also  proven to be effective in killing zebra mussels. Those that tested positive by Ohio State   University and the  National Fisheries Research Center-La Crosse researchers are as follows:
      Salt. Common table salt at a 1% (10,000 ppm) treatment rate  for 24 hours had a 100% mortality for larval and juvenile stages of the zebra  mussel.
      Benzalkonium Chloride. This chemical is recommended for use  on contaminated equipment at 100 ppm for 3 hours or at 250 ppm for 15 minutes.  It will kill all stages of the zebra mussel.
      Rotenone. This should be used to treat infected ponds.  Depending on temperature, a treatment of 1-5 ppm for 24 hours will kill adult  zebra mussels.
      Chelated Copper. Treat at 2 ppm for 48 hours to eliminate  adult zebra mussels from ponds. Toxicity of copper compounds does vary with the  pH and alkalinity.
      Hydrated Lime. Addition of calcium hydroxide to a newly  drained pond at a rate of 1000-2000 lb/acre will kill larval and juvenile zebra  mussels. Should you decide on a chemical treatment, conduct a simple  on-site bioassay to protect the environment and your investment. No chemical treatment has proven 100% effective against all  stages of the zebra mussel without harming other aquatic life forms. Be sure to  contact your state environmental agency as well as your local EPA or FDA office  to determine the latest regulations before using any chemical treatment. For  information on a particular compound, contact the Technical Information  Officer, National Fisheries Research-La Cross, WI at 608/781-6200.  **Muskrat Control** **By: Jim Steeby** Now that the cooler temperatures are only a few months away  many producers need to think about controlling nuisance muskrat populations.  The animals are particularly active between November and February when feeding  and breeding activity is at its peak, and food sources become scarce. Trapping  is the best control and, fortunately, muskrats are relatively easy to trap.  These rodents are particularly attracted to floating or partially submerged  objects and, consequently, leg-hold traps placed on naturally occurring or man  made structures close to the water line are very effective. Traps should be  attached to the structure with a foot or two of wire to establish a drowning  set. A piece of plastic netting or hardware cloth 3'x3' nailed to some 2x4s  makes a good structure to set traps on. Place this platform at water level and  stake it out with some rebar, metal fence posts or attach larger boards so it  will float. Place two to three traps on top and attach each with wire. Good  locations for the float are in areas of high muskrat activity that is easily  accessible in wet weather. A "colony trap" can also be made and works  well. Trapping licenses are usually required for these activities and can be  obtained anywhere hunting licenses are sold. Be sure to contact local  conservation officers before you start a program of control to make sure that  the trapping is legal.  Bird Damage at Aquaculture Facilities **By: W. Paul Gorenzel, Fred S. Conte and Terrel P. Salmon,  Department of Wildlife, Fisheries and Conservation Biology, Univ. Of California Davis,   CA** Reduction of the damage caused by fish eating birds requires  accurate bird identification and some knowledge of avian biology and habits.  Responsible bird management requires knowledge of both the problem species and  other birds that use the aquatic habitat without harming aquaculture efforts.  Not all birds are harmful to production efforts. Birds only become a problem if  their activities directly or indirectly result in fish loss. Many species  benefit from the association with production facilities without interfering  with production efforts. Large open-water areas are natural attractants to many  birds. Birds can have a significant economic impact on fish culture operations.  Fish-eating birds are highly mobile and adaptable predators, able to rapidly  exploit situations of food abundance. Aquaculture facilities are ideal feeding  sites for these predators. The severity of bird problems will vary with the species and  number of birds present and whether the birds reside only seasonally or tend to  remain at the facility throughout the year. The proximity of nearby nesting or roosting sites and the  availability of alternative feeding sites are also important factors. Problems  are compounded when drought impacts alternative feeding sites, especially as  the number and size of available wetlands continue to diminish due to human  activities. Besides consuming fish, birds can injure fish, disrupt their  feeding activity, disturb broodstock, and contribute to the spread of diseases  and parasites in aquaculture ponds and raceways. Bird feces can degrade water  quality and through bacterial activity, lead to reduced oxygen levels. It can  result in significant expenditure of time and funds in establishing bird  management programs and training personnel. The birds commonly responsible for most damage are herons,  cormorants, pelicans, gulls, egrets, mergansers and other diving ducks,  blackbirds, and kingfishers. Other problem species reported less frequently  include dippers, grebes, ospreys, and dabbling ducks. Because most species of  fisheating birds are diurnal, or active during daylight hours, direct observation  is the usual means of confirming bird presence and damage. Obvious signs of  hunting and feeding birds include birds perched on trees or wires near raceways  or ponds, hovering overhead and then plunging into the water, standing or  stalking along the edges of ponds, or swimming and diving in the ponds. Some species, including the black-crowned night-heron and  the yellow-crowned night-heron in particular, feed at dusk and night, when  aquaculture personnel may not be present to observe damage. Because most fish  are swallowed whole, often few direct signs of damage are left behind. The  decrease in the number of remaining fish may not be obvious for some time. In  these cases, the presence of whitewash (bird excrement), bird feathers, and/or  bird footprints may be the only signs of bird predation. Additional observations  at night should be made to verify bird depredation. Some fish may show scars  from predatory attempts. Cormorants often injure fish, allowing access to  fungal and bacterial disease organisms. Herons sometimes spear but do not kill  or eat larger brood stock. Chewed or partially eaten fish may be a sign of  predatory animals including raccoon, mink, and otters. **Legal Status and Permit Protocol** Resolution of bird depredation problems is complicated. All  fisheating birds that frequent aquaculture facilities are classified legally as  migratory and thus are protected by federal, and in most cases, state laws.  These laws were developed to protect US interest in migratory birds in  concert with the interests of other nations that provide habitat to these same  avian populations. The migratory Bird Act (16 USC 703-71 1) consists of  agreements made with foreign governments concerning migratory species and  influences US domestic laws and regulations concerning these species. **Damage Prevention and Control Methods** With the exception of total exclusion, control methods  rarely solve a bird control problem. Results obtained from nonexclusion  techniques may vary. Keep in mind that all methods succeed or fail to some  degree, and a combination of methods is usually required. The choice of control methods will be determined by a number  of factors, including the species of birds involved, the extent of the damage,  the projected cost of the control program, the type of facility to be  protected, the species of fish grown, the size of the water impoundments, and  the long-term effect on facility management. Finally, economics plays a role in  the selection process; the expected cost of the control program must be less  than the value of anticipated damage. **Exclusion** Exclusion is the complete enclosure (caging) of ponds and/or  raceways with screen or net. It is effective for small facilities, but is not  practical for protecting most ponds larger than 5 acres (2 ha). Total exclusion  is the only legal method available that provides complete, long-term control.  Complete screening or netting is effective in excluding all problem birds and  has been adopted by a number of state and federal hatcheries. Some commercial  producers have adopted complete facility exclosure or partial exclosure in  combination with other management practices. This choice is based primarily on  the monetary damage caused by the birds and/or self-protection from potential  legal consequences associated with migratory, threatened, and endangered bird  species. **Impediments** Impediments are partially covered systems with overhead  wire, line, net, or screen, and devices that discourage birds from entering a  feeding zone or perching nearby. Impediments such as overhead lines are usually  less expensive than enclosures, but do not exclude all bird species. **Overhead Wires or Lines** Ponds or raceways can be covered with overhead lines of  braided or other extruded polypropylene material, or stainless steel wire,  suspended horizontally in one direction or in a crossing pattern. These lines  should be made visible to the birds by hanging streamers or other objects at  intervals along the wires. The objective is to discourage bird feeding activities and  not cause bird injury or death. Overhead wire networks generally require little  maintenance other than maintaining proper wire tension and replacing an  occasional broken wire. Reflecting tapes are also used in overhead networks,  but they are prone to wind damage. **Perimeter Fencing or Wires** Perimeter fencing or wire around ponds and raceways provides  some protection from wading birds and is most effective for herons. For ponds,  erect fencing at least 3 feet high in water 2 to 3 feet deep. Small mesh  material can be used to prevent fish from entering the shallow water, but  maintenance costs associated with algae buildup and accumulated debris can be  substantial. Fences built in shallow water will not prevent birds from feeding  on the pond side. Great blue herons have been deterred in Great Britain with a  2-strand fence with wires at 8 and 14 inches around a pool supplemented with  floats spaced under 1 foot apart around the pool. Fences surrounding raceways should be high enough to prevent  feeding from atop the fence. Occasionally blackbirds will cling to fencing or  screening near the water and feed on small fish. A slick surface created by  securing plastic over the fence or screen will eliminate the problem. Electric fences with nonlethal levels of electric current  have also been used but with varying success. Problems include maintenance and  preventing the system from becoming grounded, commonly caused by vegetation  interference and blowing debris. Wires are strung on supports that suspend the  wire over the water's edge near the natural shelf that often forms in shallow  areas of the pond margin. This system discourages wading birds from feeding on  fish while walking along the shelf. **Metal Spines** For some situations, sharp, metal spines, sometimes called  porcupine wires may be used to deter perching and roosting by birds. The spines  prevent birds from settling on the growout or holding structures, and the fish  are protected from fecal contamination by the birds. These devices are used on  fish farms to prevent birds from perching on a structure near the water. Homemade versions of these commercial products can be built  by hammering nails through wood lath and attaching the lath at the appropriate  location. Poles or posts may be guarded against perching birds by sharpening  the end, by insertion of a guard spike, or by use of a sheet-metal cone over  the end. These devices are useful in discouraging species that hunt from an  elevated perch or at roosting sites where fecal deposits are unacceptable. **Fish Management** Fish management and the ability to adjust programs based on  changing bird habits are as important as facility design. Since fingerlings are more susceptible to bird predation,  they should be located close to the center of human activity and near buildings  that might be incorporated in a bird exclusion system. Larger fish usually need  less protection because they are better able to avoid bird predators. A  compromise strategy is to concentrate the more susceptible fingerlings under  nets covering smaller ponds, and use larger ponds and an intensive bird  harassment program to protect the larger fish. **Frightening** Frightening devices and techniques modify behavior and  discourage birds from feeding, roosting, or gathering at a location. Many  visual and sound-making devices are commercially available for scaring birds.  These include gas operated exploiters, pyrotechnics, electronic noisemakers,  bird distress calls, standing or pop-up effigies, eyespot balloons, raptor  models, strobe or flashing lights, reflective plates or lines, and water spray  devices. The value of these devices is usually limited to short-term  control. Although bird damage can sometimes be reduced by using only one type  of frightening device, better results over longer periods are often achieved by  using a combination of devices and/or by changing methods frequently. In addition, scaring equipment, especially sound-making  devices, is usually more effective when moved often to prevent birds from  becoming accustomed to the device. Birds will eventually ignore any scaring  device that is left in the same place or that emits sound in the same regular  pattern over a long period of time. **Further Assistance** The Animal and Plant Health Inspection Service (APHIS) of  USDA will provide assistance to aquaculture facilities that experience losses  to birds. If required, on-site advice and instruction in the actual use of  damage control methods is provided by the APHIS-ADC personnel. Kill permits are  not routinely issued and are contingent on approval from APHIS and the US Fish  and Wildlife Service. For information concerning assistance, permit  applications, and sources of equipment and supplies, contact the appropriate  state director of USDA APHIS-ADC.  Maximize Your Hatchery's Budget To Train Your Staff **By: MTAN** How often do you find yourself faced with the dilemma of  having insufficient revenues to spend on your hatchery program? How frequently  do you wish you had the opportunity to find good affordable training for your  hard working staff? The MTAN would like to offer one option which may save your  hatchery program training dollars that could be channeled to other areas. Fish hatchery supervisors from state and federal hatchery  systems are excited about sharing information with Tribal hatchery workers. One  of the ways this exchange is taking place is through an "On The Spot  Hatchery Experience." If you feel that your staff would benefit from a  training visit to one of these hatchery facilities, please give a call to the  MTAN so we can help to made the arrangements. Depending on your specific needs,  this kind of training could be one or several days in length and could even be  spaced out over a broad cross section of the fish rearing cycle. The only  expenses incurred to your program would be for travel, meals and lodging.   **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.
 
  U.S. Fish and Wildlife Service Home Page Department of the Interior USA.gov About the U.S. Fish and Wildlife Service Accessibility Privacy Notices Disclaimer FOIA
 Find Office By ProgramAdministrationEcological ServicesExternal AffairsFisheriesLaw EnforcementMigratory BirdsRefugesState Programs