Dedicated To The Tribal Aquaculture Program
 |
December 1992 - Volume 2 |
http://www.fws.gov/midwest/ashland/mtanhome.html
| Administrative
Coordinator:
Frank G. Stone
(715-682-6185) Ext.12 |
Edited By: Elizabeth W. Greiff
(715-349-2195) |
Topics Of Interest:
- Walleye Fingerling Fertilization in Earthen Ponds
- FmHA Aquaculture Loans
- Zebra Mussel
- Toxic Bait For Carp Control
- Stress and Fish Culture
- Walleye - A Light and Temperature Experiment
- Radon Gas
Walleye Fingerling Fertilization in Earthen Ponds
By: Larry J. Wawronowicz, Lac du Flambeau Indian Reservation
The techniques used to produce walleye fingerlings are varied depending on environmental, biological, chemical and physical parameters of the pond, water supply, watershed, etc. Success or failure of a production season depends on the ability of the pond managers to consider the above parameters when making pond management decisions. The main objective of pond culture, regardless of the species raised, is to increase primary productivity by utilizing fertilizers. A pond manager will fertilize a pond for the same reason a farmer will fertilize a corn field, to increase the number of bushels of corn per acre to feed cattle. The pond manager will increase primary productivity by fertilization to convert the sun's energy to phytoplankton to zooplankton to fish biomass.
The types and combinations of fertilizers used can be organic and/or inorganic. Chicken manure, alfalfa meal, torulas yeast, whey, hay and pig manure are examples of organic fertilizers. Inorganic fertilizers are represented by 18-46-0, 10-10-10 and super triple phosphate. Inorganic fertilizers are available in liquid and granular forms. Agricultural lime may also be used to buffer the soil and water to more effectively use the fertilizer. The type, amount, and/or combination of fertilizers used depends on soil fertility, soil pH, water pH, soil and water buffering capacity availability, pond manager's experience and preference, and success or failure of a production season.
In Lac du Flambeau, agricultural lime (2,000 pounds/acre), alfalfa meal (500 pounds/acre) and torulas yeast (50 pounds/acre) are applied to the pond bottom or water column at various times during the production season. All of the agricultural lime is applied to the pond bottom and disked into the soil before the pond is filled. Approximately 10 days before the walleye fry hatch, the ponds are filled and 250 pounds/acre of alfalfa meal and 25 pounds/acre of torulas yeast are applied to the pond. The balance of the fertilizers is applied during the 30-45 day growing season. Generally, a pond is fertilized weekly with 63 pounds/acre of alfalfa meal and 6.5 pounds/acre torulas yeast.
The fertilization program described will produce daphnia's and copepods which are preferred by young walleye. The time to apply the balance of the fertilizer will be determined by the pond manager when the zooplankton populations are sampled (2-3 times/week), oxygen concentration at first light is determined, and weather conditions evaluated. The relative abundance, species composition, and quality of the zooplankton must be monitored and noted. If, for example, the number of zooplankton has decreased, there is no sign of recruitment, the pond color changes, walleye fingerlings are foraging in front of the water intake, etc., it is time to fertilize if oxygen concentration and weather conditions are desirable. The pond manager may choose not to fertilize if the first light oxygen concentration was below 5 mg/l and the weatherman is predicting 5 consecutive cloudy days and high humidity. Under these conditions, increasing the biological oxygen demand caused by the decomposition of additional alfalfa meal and torulas yeast may cause an oxygen depletion.
The fertilization program described will produce on the average 58,100, 1.5-2.0 inch walleye fingerlings per acre annually during a 30-45 growing season. Annual production has ranged from 22,200 to 98,000 walleye fingerlings/acre depending on the production year. The Lac du Flambeau fertilization program was developed by analyzing the pond soils, trial and error, and the intuitive reasoning of the pond manager.
According to Mike Navin, Native American Coordinator for Farmer's Home Administration (FmHA) State of Minnesota, FmHA has a program directed specifically toward Native Americans. Mike said that under this program, loans are available for Native American's interested in Aquaculture farming. The loans are not available for tribal programs, rather individuals only. You can reach Mike at (612) 290-3842.
Based on the experience of electric generating stations and municipal water systems in dealing with zebra mussels, it may be just a matter of time until a fish hatchery becomes affected.
Biologists believe that the interbasin transport of the zebra mussel from the Great Lakes system into inland fresh surface waters is taking place via natural and human influenced dispersal vectors, and that the mussels will ultimately infest most areas of North America south of central Canada and north of the Florida Panhandle.
Such dispersal will likely be greatly enhanced by interlake transport of veligers (larvae) in ship ballast, and adult and juvenile mussels attached to ship and recreational boat hulls. There is concern that the range expansion of the zebra mussel will be further facilitated by transport of veligers by commercial bait transport, in angler's bait bucket water, recreational boat engine cooling water, plus transport of juveniles and adults by waterfowl and by attachment to crayfish and turtles. With this in mind the time is right to develop a monitoring program at your hatchery facility.
Toxic Bait Strategy Effective For Carp Control
Common carp can pose major problems for fisheries managers when their feeding activity degrades valuable fish and waterfowl habitat. Several methods are available to help reduce carp numbers: angling, electrofishing, construction of barriers, water level manipulation, baited traps, nets and also toxicants. If you feel that toxic bait is needed you may want to look into the use of Antimycin. Toxic baits would be especially effective if carp were congregated in small areas. This might be best achieved by baiting a preselected area or through water level manipulations. For the toxic bait to be effective, the carp should be actively feeding during the application. The question of limiting the losses from nontarget organisms such as waterfowl and other fishes will also need to be addressed. For more information regarding the use of Antimycin contact Jeff Rach at the USFWS National Fisheries Research Center, La Crosse, Wisconsin (608-783-6451).
By: MTAN
The following topic was selected from "Introduction To Fish Health, published by the U.S. Fish and Wildlife Service.
Stress in fish may be described as a fish's physical response to an environmental change. These physical responses can include blood hormone and other cellular changes as the fish try to regain internal equilibrium to an external environmental change that has displaced the internal equilibrium.
There are many environmental changes associated with the intensive culture of fish which are capable of disrupting the fish's internal balance. These changes include unfavorable or fluctuating water temperatures, ammonia and nitrate levels, and dissolved oxygen concentrations. In addition, management practices such as handling, crowding, transport, anesthesia, and therapeutic treatment can all disturb the delicate internal balance of the fish.
Typically, the response of the fish to most of the human activities is fright. Frightened fish move about rapidly and their oxygen demand increases considerably. If the stress continues, the fish's ability to restore its internal balance becomes less and less. Stresses requiring an adjustment exceeding the fish's ability to accommodate are often lethal. Sublethal responses to chronic or acute stress in fish are seen in behavioral changes, production traits (growth, weight gain or loss, food conversion) and disease outbreaks. These changes are the fish's way of showing that it is suffering from a stress it can no longer deal with and if the stressor is not reduced, these sublethal responses may become lethal.
Because many of the stresses are related to human activity, several are controllable through a change in management practices. The following recommendations will assist in decreasing hatchery related stress:
1. Reduce handling of fish to a minimum.
2. Avoid temperature shock.
3. Stresses may be additive; allow recuperation between stressful situations.
4. Avoid high loading densities.
5. Maintain optimum water quality conditions.
Comments on Good Management
Management has the responsibility to raise the highest quality fish for its programs. To accomplish this task the following must be taken into consideration.
1. Avoid hatchery to hatchery transfer of fish.
2. Maintain water supply systems free of fish and other aquatic life.
3. Provide optimal environmental conditions for the species being raised, paying attention to maintaining optimal oxygen levels, and minimal ammonia levels. Attempt to keep densities low.
4. Handle fish gently, and where there is a seasonality to disease outbreaks, avoid handling fish two to three weeks prior to and during the expected time of usual outbreaks.
5. Maintain cleanliness of rearing facilities. This includes segregated fish handling equipment or strict practices of disinfection of nets and other equipment between lots of fish. This also includes picking out mortalities and fish showing distinct signs of stress, disease, or failure to survive.
6. Where appropriate, use strains of fish species which show resistance to the specific endemic disease problems.
7. Disinfect all salmonid eggs spawned on-site or shipped to station with a polyvinylpyrrolidone iodine compound.
8. When stress is unavoidable, allow sufficient recovery time, based on the physiological disturbances involved, before again handling or stressing fish.
The fish culturist who has frequent contact with the fish should be the first line of defense against a full-blown disease outbreak in a fish population. The fish feeder sees the fish regularly and should be alert to subtle changes which may precede significant losses.
Observations to note are as follows:
Changes in appearance or behavior from normal. We must first know how a normal fish looks and acts. The internal examination of healthy fish is as important as an external examination. Fish in poor health gather near the incoming water supply, do not feed well, are sluggish, and may flash on the bottom of the holding unit.
Changes in vitality. Fish in good health quickly flee from disturbances. Symptoms of fish in poor health are: fin erosion, loss of balance, general sluggishness, not reacting to disturbances, swimming with the head high up in the water, and crowding the inlet.
Changes in the feeding pattern. Fish in good health feed actively and clean up the food within minutes. Fish in poor health may cease to feed. High water temperatures, low oxygen, crowded holding units, parasites and bacterial infestation cause fish to go off feed. ANY TIME FISH GO OFF FEED FIND OUT WHY !!!!
Sores, lesions, coloration or ghostly appearance. A complete examination may be needed but the appearance of any of the above usually indicates disease or physical problems.
The following two topics were taken from the January 1992 issue of "The Progressive Fish-Culturist".
By: Gary Siegwarth and Robert Summerfelt
Abstract. Growth, survival, and feed conversion of walleye (Stizostedion vitreum) and F1 hybrid fingerlings were compared under conditions of submerged and overhead lighting. We also compared these variables for the hybrids at 20 and 25C. After 71 d, walleyes reared with submerged lighting were longer than walleyes reared with overhead lighting. Other differences in performance between light treatment groups for walleyes were not significant. The performance of the hybrids was unaffected by temperature or light regime. Hybrids were longer and heavier than walleyes when reared with overhead lighting, but not when reared with submerged lighting. Hybrids had better feed conversion than walleyes when reared with submerged lights, and higher survival in both light regimes. Growth differences between walleyes and hybrids found in the present study and in previous investigations were reduced with the use of submerged tank lighting. Submerged lights also reduced agitation of the fish from shadows of people that were caused by overhead lighting.
Removal of Radon Gas Liberated by Aeration in Fish Hatcheries
By: Wesley Orr
Abstract. Radon gas, a radioactive by-product of uranium decay, is found in groundwater in some areas of the country. Aeration of this water can cause radon gas to be released into the atmosphere. Exposure to radon gas by-products is a health concern because of the increased risk of lung cancer. High levels of radon gas have been measured in fish hatchery buildings, and in some cases, are due to the water flowing through the aeration columns. We developed a simple inexpensive method to reduce the radon problem at Ennis (Montana) National Fish Hatchery. Radon levels in the hatchery building were measured at 200-250 picocuries radon/L air (Pci/L). The U.S. Environmental Protection Agency guidelines recommend remedial action when radon levels exceed 4 Pci/L. Because air is drawn down through aeration columns, we were able to put a collector at the base of the column to collect the off-gas coming out of solution. Off-gas collectors were installed on 38 packed columns at a cost of US$600. Since installation of the collectors, radon gas levels have decreased from 250 Pci/L to 25-40 Pci/L. The off-gas collector is a simple inexpensive method to reduce the magnitude of a dangerous health problem.
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. |
