AALAS_02

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Information about AALAS_02
Science-Technology

Published on January 12, 2009

Author: aSGuest10171

Source: authorstream.com

Optimization of Zebra DanioPerformance : Optimization of Zebra DanioPerformance BY Dallas E. Weaver, Ph.D. Scientific Hatcheries Huntington Beach, Ca The “Devil is in the Details” : The “Devil is in the Details” The biology of zebra fish interacts with the culture system, water chemistry, husbandry details and nutrition. Aquatic Animals vs. Land Animals : Aquatic Animals vs. Land Animals Designing and operating zebra systems is a lot like trying to design and operate mice systems in zero G. You don’t have gravity to separate the waste products from the animals. Performance : Performance Definition of performance Egg production and fertility Embryo development and hatching Larval survival and initial growth Growth rate Maturation -- egg to egg time Egg production and fertility : Egg production and fertility Number of eggs per gm of female Fertilization percentage Cannibalism Egg health -- yoke size Factors impacting egg production : Factors impacting egg production Water quality Metabolic waste products -- non-detectable Ammonia, nitrite < 0.05 ppm in tank input water Other chemicals Nitrate 0 to 75 ppm Salinity 100 to 2,000 ppm pH 6.0 to 8.0 Temperature 20.5 ºC to 28.5 ºC Pushing the limit on one variable reduces the range of other variables. Factors impacting egg production : Factors impacting egg production Nutrition No real research into zebra maturation diets Quality aquaculture diets all have short shelf life problems. Age dating, inventory cycling. Omega-3 fatty acid requirements Vitamin requirements Water soluble (C, B, etc) -- leaching problem Oil soluble (E) Factors impacting egg production : Factors impacting egg production Nutrition practice by Scientific Hatcheries Dry diet of custom formulated modified salmon diet. High fishmeal protein, unsaturated fats (high % omega-3 fats). Frozen adult artemia Live moina, rotifers, artemia for maximum production. Factors impacting egg production : Factors impacting egg production Cycling Observation that off cycle fish have low fertility. May be related to over-ripe eggs Density At densities > 10,000 / M2 of spawning surface fertility decreases. Performance : Performance Definition of performance Egg production and fertility Embryo development and hatching Larval survival and initial growth Growth rate Maturation -- egg to egg time Embryo development : Embryo development Impacts on development Chemical stress from water quality Non-viable embryo problem -- static systems Toxins from materials Interaction between embryos may impact sex ratio Unstable microbiology -- bacterial/fungal attack on the embryos Embryo development : Embryo development Chemical stress from water quality Static systems Non-viable embryos source of pollutants Food supply for bacteria Ratio of volume per embryo critical Depth irrelevant Surface tension will be relevant at hatch Flowing system Water quality determined by source water. Toxins from materials : Toxins from materials Bioassay all materials Test materials with embryos and larva Problems materials Rubber -- black rubber Vinyl tubing, brass valves at low alkalinity Cleaning solutions and sterilization solutions Solutions Rinsing, leaching and materials selection Flowing water Embryo development : Embryo development Interaction between embryos may impact sex ratio Static systems can have interactions Many researchers have sex ratio problem Hypothesis: developing embryos can release chemicals that can impact the development of other embryos exposed to those chemicals. Embryo development : Embryo development Unstable microbiology -- bacterial/fungal attack on the embryos Static systems -- dishes, beakers, etc. Dead embryos and non-viable embryos provide nutrients for bacteria and fungal growth Once fungal or bacterial attach on non-viable, attack on viable embryos is possible Flowing systems Upflow system -- not a problem Non-upflow -- fungal problems Embryo development : Embryo development System options Static systems All the problems Easier to work with embryos Fluidized Bed Hatchers Eliminates the problems of static system Automatic non-viable removal Automatic fungus egg removal Embryo Development : Embryo Development What is a Fluidized bed Hatcher A fluidized column of glass bead media with a fluidized column of embryos behaving like a second phase fluid With a constant up-flow velocity, non-viable embryos swell up and float out of the hatcher. Every embryo has a constant supply of clean water which decreases developmental differences caused by oxygen differences in static systems. Performance : Performance Definition of performance Egg production and fertility Embryo development and hatching Larval survival and initial growth Growth rate Maturation -- egg to egg time Larval survival : Larval survival Ideal is 100% survival for all normal embryos Factors causing unnecessary mortality Water quality Nutrition “Weak larva” Larval survival : Larval survival Factors causing unnecessary mortality Water quality Normal pollutants, ammonia, nitrite and metabolic waste products, low oxygen Surface tension -- oil film -- swim bladder inflation Toxic chemicals Bacterial/protozoan explosion Larval survival : Larval survival Factors causing unnecessary mortality Water quality (continued) Surface tension -- oil film -- swim bladder inflation Zebra fish need surface access for filling the swim bladder. Common problem with other aquaculture species (striped bass, white bass, etc.) Solution is keeping the surface free of oil Tank depth is irrelevant. Larval survival : Larval survival Factors causing unnecessary mortality Water quality Nutrition “Weak larva” Larval survival : Larval survival Factors causing unnecessary mortality Nutrition First food is critical Notes from Aquaculture Larval fish/shrimp production is a multi-billion $ business Dry diets can’t replace 100% of live feeds for all small larva species. Dry diets are only supplements to cut the cost of live feeds. When dry diets appear to work, it is often the bacterial/protozoan contamination of that diet that allows it to work. Leaching of critical nutrients from dry diets is very fast Larval survival : Larval survival Factors causing unnecessary mortality Nutrition (continued) Notes from Aquaculture (continued) Rotifers (brackish water species) is the most common small live feed. For species where new hatched artemia is too large. Rotifers are often enriched before feeding with algae or prepared omega-3 fat blends. Rotifers can be packed with antibiotics or other chemicals. Can be purchased alive or produced locally. Larval survival : Larval survival Factors causing unnecessary mortality Nutrition (continued) Notes from Aquaculture (continued) Artemia napulii Easy to hatch Nutrition value decreases with time when un-fed Nutrition value variable Enrichment is a common practice -- improved fatty acid profiles and amino acid profiles are possible Digestive enzymes are limited in many larval fish Depend upon live food to provide Larval survival : Larval survival Factors causing unnecessary mortality Water quality Nutrition “Weak larva” Larval survival : Larval survival Factors causing unnecessary mortality Weak Larva Can be caused by poor adult nutrition Stressing the larva during development Stressing the larva with high density Social interaction problem Too much turbulence wasting energy reserves A problem with McDonald jars for hatching Performance : Performance Definition of performance Egg production and fertility Embryo development and hatching Larval survival and initial growth Growth rate Maturation -- egg to egg time Growth rate : Growth rate Factors impacting growth rates Temperature Water quality Nutrition Density Growth rate : Growth rate Factors impacting growth rates Temperature There is a maximum above which metabolism is greater than digestible feed consumption. With a low quality diet, the rearing temperature could be above the maximum. Apparently parameters are not available for a zebra fish bio-energetic model. Growth rate : Growth rate Factors impacting growth rates Temperature Water quality Nutrition Density Growth rate : Growth rate Factors impacting growth rates Water quality Low Oxygen levels decrease growth Very high unionized ammonia levels > 20 ppb unionized Pheromones give an apparent density dependence that is not real. Growth rate : Growth rate Factors impacting growth rates Temperature Water quality Nutrition Density Growth rate : Growth rate Factors impacting growth rates Nutrition This is a critical element Live feeds are the best Enrichment is desired All they can eat all the time 7 days a week Excess feed and old feed may decrease growth rate and support enteric diseases. Growth rate : Growth rate Factors impacting growth rates Temperature Water quality Nutrition Density Growth rate : Growth rate Factors impacting growth rates Density Often misinterpretation of observations Apparent impacts from water quality Apparent impacts from nutrition Real impacts result from social interaction Real impact density > 35/liter for zebra fish or 1.5% zebra fish in the water Below those levels, apparent density impacts of slow growth, growth variation, etc. are artifacts of other problems. Performance : Performance Definition of performance Egg production and fertility Embryo development and hatching Larval survival and initial growth Growth rate Maturation -- egg to egg time Maturation -- egg to egg time : Maturation -- egg to egg time Putting it all together and adapting commercial aquaculture technology to zebra fish Use a standard Aquaneering FBB rack system Use standard zebra research artemia hatching tank -- tank for automated feeding Use de-chlorinated tap water at 28.5 ºC Maturation -- egg to egg time : Maturation -- egg to egg time Special additions Fluidized Bed Hatchers for development Black tanks for experiment on tank color (significant for many species of fish) Peristaltic feed pump -- automated feeding Timer, rotifer supply, artemia supply (enriched) Inlet diffuser for mixing feed with main flow Turbulent flow control valves on each tank Fine discharge screen baffles -- 300 µ Maturation -- egg to egg time : Maturation -- egg to egg time Additions (continued) Air injection behind screen (improved oxygen transfer without excessive turbulence) Monitoring of salinity -- live food additions were with brackish water Maturation -- egg to egg time : Maturation -- egg to egg time The experiment Four clear tank, Four Black, Four density classes ResultsEGG to EGG 49 days : ResultsEGG to EGG 49 days

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