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Give me technical guide on decreasing salinity level in Larval rearing tank. I want to drop down salinity level from 25 PPT to 0 ppt in 7 days duration in L.Vannamei Laraval's PL stage in larval rearing tank by adding Fresh water source. While decreasing salinity level PL s get stressed. How to avoid/ reduce stress in L.Vannamei PLs during that process. To balance Minerals loss, I add calcium carbonate & Magnesium cloride into the water to make PLs feel less shock from the sudden salinity level change. Is there any formula for how much calcium & Magnesium or any other minerals need to be added into the water for every salinity PPT downing to make PLs strong?
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@all Decreasing the salinity level in a larval rearing tank can be a delicate process, and it's important to minimize stress on the L. Vannamei post-larvae (PLs) during this transition. Here's a technical guide to help you decrease the salinity level while reducing stress and maintaining the PLs' well-being:
  1. Gradual Salinity Reduction: Instead of attempting to drop the salinity level from 25 PPT to 0 PPT in just 7 days, it's advisable to do it gradually over a longer period. Rapid changes in salinity can cause stress and harm the PLs. A recommended approach is to decrease the salinity by 3-5 PPT per day.
  2. Monitor PLs' Behavior: During the salinity reduction process, closely observe the PLs for any signs of stress or abnormal behavior. If you notice increased mortality, lethargy, or abnormal swimming patterns, it might be an indication that the salinity change is too rapid or stressful for the PLs.
  3. Maintain Water Quality: To reduce stress during the salinity reduction, ensure that the water quality parameters remain stable. Monitor and maintain optimal temperature, pH, dissolved oxygen levels, and ammonia/nitrite levels. Any fluctuations in these parameters can further stress the PLs.
  4. Acclimation Tanks: Consider setting up acclimation tanks or compartments within the larval rearing system. These compartments can act as intermediate zones where salinity is gradually reduced. Transfer the PLs to these compartments first and then further decrease the salinity over a couple of days until reaching the desired level.
  5. Calcium and Magnesium Supplementation: Adding calcium carbonate and magnesium chloride can help balance mineral loss during the salinity reduction process. However, it's important to note that the amount of supplementation required may vary depending on the specific water chemistry and the rate of salinity reduction. There isn't a specific formula to determine the exact amounts of calcium and magnesium for each salinity PPT decrease. It's recommended to consult with a marine biologist, aquaculture expert, or water chemistry specialist who can analyze your water parameters and provide tailored recommendations.
  6. Water Testing and Adjustment: Regularly test the water parameters, including calcium, magnesium, alkalinity, and other essential minerals. Adjust the supplementation amounts based on the test results and the observed behavior and health of the PLs. It's crucial to strike a balance between preventing sudden changes in water chemistry and maintaining optimal mineral levels for the PLs' health.
  7. Observing PLs' Response: Throughout the salinity reduction process, carefully observe the PLs' response and adjust the rate of salinity reduction accordingly. If you notice signs of stress or if the PLs are not adapting well, slow down the process and allow them more time to acclimate.
Remember, maintaining the health and well-being of the PLs is of utmost importance. Consult with experts in the field, gather data on the specific water conditions and PLs' responses, and make adjustments based on observed outcomes.
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What Causes the green color change? Because Diatoms are produce brown color tint in the tank. Does It lead high mortality rate in shrimp post larvae in larval rearing tank
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@all Apologies for the confusion in my previous response. You are correct that Thalassiosira weissflogii diatoms typically produce a brown color tint in the water rather than a green color. I apologize for the oversight in my previous explanation.
In the context of shrimp larval rearing tanks, the presence of a green color in the water is more commonly associated with the overgrowth of green algae, such as species from the genera Chlorella, Nannochloropsis, or Tetraselmis. These green algae can proliferate under favorable conditions and lead to the water turning green.
Excessive green algae growth can have various impacts on the larval rearing tank and the shrimp post-larvae (PL). While green algae themselves are not usually directly harmful to shrimp larvae, their overgrowth can indirectly affect the larvae and potentially lead to high mortality rates. Here are some possible reasons for the negative effects:
  1. Reduced oxygen levels: Dense algal blooms can deplete oxygen levels in the water, leading to hypoxia or low oxygen conditions. Shrimp larvae require sufficient oxygen for their growth and survival. If oxygen levels become critically low due to the excessive growth of green algae, it can result in stress and mortality of the PLs.
  2. Changes in pH and alkalinity: Algal blooms can alter the pH and alkalinity of the water as they consume carbon dioxide during photosynthesis. Rapid changes in pH can stress the shrimp larvae, affecting their physiological processes and increasing mortality rates.
  3. Competition for nutrients: Green algae compete with the shrimp larvae for nutrients in the water, particularly nitrogen and phosphorus. If the algae outcompete the larvae for these essential nutrients, it can negatively impact the larvae's growth and development.
To prevent or manage excessive green algae growth and mitigate potential risks to the shrimp larvae, you can consider the following measures:
  1. Nutrient control: Monitor and manage nutrient levels in the water, particularly nitrogen and phosphorus, to limit algal growth. Properly balanced nutrient inputs can help prevent excessive algae proliferation.
  2. Light control: Adjust the lighting conditions in the larval rearing tank to prevent excessive algae growth. Algae require light for photosynthesis, so reducing the light intensity or using shorter lighting periods can help control their population.
  3. Filtration and water exchange: Implement an appropriate filtration system to remove excess algae from the water. Regular water exchanges can also help dilute the algal population and maintain water quality.
  4. Monitoring and management: Regularly monitor water quality parameters and observe the behavior and health of the shrimp larvae. If excessive algae growth occurs, take appropriate actions to mitigate its impact, such as adjusting nutrient levels, increasing filtration, or implementing additional water exchanges.
By maintaining optimal water conditions and preventing the overgrowth of green algae, you can help reduce stress on the shrimp post-larvae and minimize potential mortality rates.
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In shrimp hatchery, usually water exchange takes place after animal reached postlarvae stage. So how to retain the probiotic microbiome again quickly in order to avoid pathogenic bacteria's bloom???
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How we can maintain the probiotic microbiome again quickly after water exchanges, in order to avoid pathogenic bacteria's bloom ? 1. Hatchery technician commonly use Bacillus sp. & lactobacillus probiotic powder directly apply it to the water or at the first we activated them by culture, 2. We should notice that water supply had been desinfected before use it, 3. We should maintain rasio C:N at raised more than 15, 4. We should control alkalinity as one of limiting factor for maintain probiotic as biofloc.
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Is it only Balancing input C:N ratio, Promoting suspended-growth nitrification or any other management practices.
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A combination of factors favours good bioflock development. C:N ratio is most important among them. Other factors are total solids concentration, type of bacteria inoculam given into the culture system and probiotics bacteria developed and microbial Colonies developed.
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An alternative livelihood can be generated from marine algae.
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Sargassum is a type of seaweed or brown algae (macro-algae) which generally inhabit in shallow water and coral reefs.
  • This algae can be used to make paper, tissue paper or paper bags, as it usually consists of cellulose and hemi-cellulose which are raw materials of paper (preventing cutting of trees to make paper or prevent use of plastic bags).
  • Can use dry algae biomass to burn as fuel, replace coal with dry algae as it will release less carbon dioxide.
  • Can be used to make cosmetics, makeup, pharmaceutical products, sunscreen, anti-aging cream and for hair strengthening treatments. Sargassum is rich in iodine, bromine, mineral salts and vitamins and also have the ability to absorb fats.
  • Seaweed can be used to treat joint pains and skin diseases (burns), as they have high antimicrobial, antioxidant and anti-fungal properties.
  • Seaweed is also used in food and beverage industry, normally used in cocktail drinks.
  • Farmers can use seaweed as fertilisers. they should collect the algae from the coastal zone which will indeed benefit the ocean as it allows a better survival rate of marine organisms. The farmers should let it dry in the sun for two to three days, wash and store for later use.
  • Sargassum seaweed is a nutritious food rich in carotenoids, cellulose, protein, and aspartic and glutamic acids. Sargassum seaweed contains polysaccharies, which support healthy bloody pressure and blood sugar.
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Stock assessment  and management of fishable marine resources are ultimately based on fishing mortality. If the populations of fishable marine resources appear overexploited, the solution generally recommended to policy makers is to reduce fishing effort. Wisely, many policy makers take into account the mortality of the fishermen through measures such as "loss of income" etc .. Unfortunately policymakers, pressed by the fishermen’s lobby, often excessively favour the fishermen in fear of losing support.
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Hi. I think it dhould be directly proportional and not inversely proportional.
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Hi all,
I would need to quantify amino acids present in hepatic vein of a fish. Do I also need to record the blood pressure to get the exact AA levels in the fish blood?
Thanks.
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I will do experiments in aquaponics for integrating tilapia and lettuce.
Can I use polyethylene tank and black color??or must be fiberglass and other color??
The problem I can not buy fiberglass.
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I following the best answer.
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Impressive sharings! Regarding on that matter,somehow people use kind of tamarind whichever in paste or liquid to get rid offlavor on flesh fish,wondering is it live fish can be done that way after post-harvest before being distribute into market?
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Ervynna Christy Bandong and Simon C. Wilson In Bangladesh, the fish farmer moves the fish from pond to river cage one week before marketing and it shows that the off-flavor improvement and customer satisfaction.
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Dear acquaintances: Anybody with an experience of farming with Mugil cephalus (mullet) fish; its growth performance, diet composition, appropriate culture systems, water quality  parameters suitable range, breeding, diseases, management etc? I  Will highly appreciate it if you attach reference documents too.
Regards
Gabriel 
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Contact Dr Dario Vallainc at the International Marine Centre
He is currently optimising larval rearing and reproduction here in Italy
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Dear Everyone,
Could you please suggest me any Organisation/ company/ government that have fund/research grant for international research in aquaculture/ marine biology or related fields? (I can use the fund to do research in any lab/any country).
Thank your so much for your time. I really appreciate you time and answer.
Thao
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WWF
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what is the difference between monitoring and maintenance of water quality such as pH,EC, Salinity and alkalinity in aquaculture and aquaponics.
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Maintenance is regularly keeping it at desired levels and ranges while monitoring is regularly checking to know if the parameters are normal. For example, an aerator may be introduced or water replaced to correct problems with DO. That's maintenance. Monitoring will help unravel this situation. So monitoring helps in maintenance.
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The fish are kept under a re-circulatory system, fed on 0.25 mm Skretting at an interval of 1 hour everyday, and the excess feed (if any) is siphoned out regularly. Average water temperature is 28 degrees centigrade .
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Environmental factor and biological factor have affect on
three weeks old African Catfish
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Generally, to maintain ecological status, five factors are considered for a river ecosystem:
1. flowing water that is mostly unidirectional
2. a state of continuous physical change
3. many different (and changing) microhabitats
4. variability in the flow rates of water
5. plants and animals that have adapted to live within water flow conditions.
During water distribution of trans border water resources, only water is considered irrespective of water ecology. If we want to consider river ecology, especially for maintaining fish population, and want to estimate minimum water flow, what procedure may be adopted to identify minimum required flow?
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There have been various instream flow methodologies developed. A lot depends on the natural range of variation and species present. Some use a minimum value of 7Q10 (the weekly average low that occurs at 10 year frequency). For channel maintenance, there should be at least a bankfull event every year or two to prevent vegetation encroachment, move sediment to maintain channel dimension. I would suggest that one size or cookbook approach is not going to fit all circumstances. Perennial side tributaries along rivers can be localized habitat refuges of cool water and elevated oxygen for mobile species as they enter warm and low oxygen rivers. Fishery and aquatic biologists are apt to have information on the needs of species present. There may be other water use needs to consider, such as swimming, scenic, water available for emergencies as fire control, community and industrial needs, waste treatment and water discharge standards, etc. Some ecosystems also provide important habitats for water birds and animal species.
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There is a directive in Ghana by the Ministry of Fisheries and Aquaculture Department to ban all imports on ornamental fishes and Tilapia species including gametes-eggs and milts from now to the close of the year as an immediate response to halt the spread of the virus which is said to be prevalent in Africa, South America and Asia, especially in farmed Tilapia. This is a blow against the global Tilapia industry.
Kindly share your views on the new virus, ways of preventing it and other references. Thanks in advance. Best regards
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Following
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I am working on integrated fish farming system. The size of pond is about 0.1 hectare. I need to study the growth of fish at different interval. The size of fish stocked are not uniform. Please suggest me how sampling can be done. should I keep some fishes in cages. what statistical design will be implement 
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Thanks Dr. Sahadeven Payyadakath, It will be very helpful in my studies.
Regards
Sahar
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Referring to traditional aquaculture in Asia, carrying capacity is the primary basis of natural production in a closed water body, like a pond. Aside from this, fertilization and application of feeds enhance fish production. Pollution caused by  pond effluents also needs to be considered for ensuring sustainable aquaculture.   
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For intensive production in fed ponds, nutrient loads are limiting.  The amount of respiration affects night time oxygen levels.  Phytoplankton and zooplankton have the greatest impact on respiration in ponds (roughly 4 times greater than that of fish).  Nutrient loads stimulate growth of plankton biomass.  Nutrient loads are directly related to the amount of feed fed.  A standard U.S. catfish production recommendation is that 1.0 hp of mechanical aeration should be available for each 22 lb of feed/acre (4 acre-feet) fed per day for intensive aquaculture.
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We want to calculate the contribution of nutrients to sediment in salmon farming.
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Please read about the use inert substances in feed.... Like chromium oxide....
Also, u can use isotopes of the elements to detect them......
Regards
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Except rotifer
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In general predator for a phytoplankton is a zooplankton, as ciliates, and protozoa(rotifer ect.)
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Dear all 
In order to pursue closed mesocosm study on zooplankton and phytoplankton, I'd like to know the amount of innoculum to be inoculated for mesocosm tanks with capacity of 100 liters.  Please also advice me with insights about closed mesocosm. 
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Hi Umer,
Thanks for sending the details. I’ll put my response here in case other people want to chime in with suggestions and comments.
I don’t know of any formulae for how much to dose a mesocosm/microcosm with, except for the work of Frieda Taub in the 1980s-90s (Taub, 1989, 1997), where she had cultures of particular species and counted in various numbers of each.
Taub, F.B. (1989). Standardized aquatic microcosms. Environmental Science and Technology 23, 1064-1066.
Taub, F.B. (1997). Unique information contributed by multispecies systems: examples from the standardized aquatic microcosm. Ecological Applications 7, 1103-1110.
If you think about why people use mesocosms, this makes sense. Mesocosms are usually intended to model some real-life environment on a smaller scale, with replications so you can do manipulative experiments with statistical analysis. Therefore the quantity inoculated will vary depending on your experimental question and which environment you are intending to model. Often people just use water from the site where they are working, without concentrating and dosing, so the density of organisms matches the environmental densities in the field.
There are a number of things you need to consider when deciding on your dosing density. You need a high enough density to allow you to take sample volumes with enough organisms to give statistically sound results, but it’s preferable if you don’t have so many organisms that the density is no longer environmentally relevant and starts to cause major changes in the conditions in the mesocosms (dissolved oxygen fluctuations, nutrient changes and so on). If you are expecting large decreases in the populations, think about whether you'll be able to get decent samples from lower densities. If you can, have a chat with a statistician about the likely power of the experimental design you are choosing, and what will be the best way of doing the analyses. If you are testing toxicants, have a look at papers by Paul van den Brink, Theo Brock and their co-workers for ideas on experimental tests in mesocosms. Alternatively, if you can find any reported studies similar to what you are planning, they may give you a guide.
My experience has mostly been with macroinvertebrates in freshwater artificial stream mesocosms, which are a bit different from tanks with plankton, but the issues above would apply to any systems. Another issue that regularly comes up in mesocosm studies is variability among the replicates, so the more replicates you can set up the better!
All the best, Anne
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An article stated this:
Addition of a little amount of NaCl in the ambient medium especially in the case of tilapias, might be of advantage, but the system has to be sufficiently modified since conditioning is often done in open waters.
Salt is removed with water in open waters. Does anyone know how the system can be modified? or has other methods?
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Hi Kelvin
The attached file could have helpful information about your question.
Best wishes
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Some contradictions I'm facing:
Sodium bicarbonate is highly alkaline, does that mean it increases water pH? Fish excretes ammonia during transportation, it gets toxic when pH is high, why would people still add sodium bicarbonate into water?
Sodium bicarbonate produces carbon dioxide when react with water, carbon dioxide produces carbonic acid when react with water, doesn't that decrease the water pH? To what level will the pH decrease? It harms fish's respiration if the water is too acidic.
Hope someone can help me with this!
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The reason people add sodium bicarbonate (baking soda) is to increase alkalinity. If alkalinity is low, pH is most likely a little low as well depending on other stats of the water quality. Alkalinity is important mostly for inverts and animals that produce chitin. There is an online calculator for dosing your water. It calculates what your pH will turn out to be after adding a certain amount in salt water. 
Hope this helps!
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Dear researchers would like to know the possibility of arabian seabream Acanthopagrus arabicus (latus) and sobaity Sparidentex hasta cultivated in concrete tanks and what better stocking densities and water flow rate.
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Thank you very much S. K. Paul
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I am working on a data whose sample size is very small (about 10). I know bootstrapping can help generate accurate standard errors of the mean etc. I however wanted to save the bootstrapped sample that SPSS generates which it uses for the determination of the confidence intervals. The idea was to play around with this generated data itself. There seem to be no way around this in SPSS, or is there?
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hi dear Simon
a friend of mine worked on paper that its method was bootstrap, he implemented bootstrap in spread sheet (Excel) and generated the bootstrap sample by Visual basic, but unfortunately I don't know how.
best....
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I need the steps for each measurement, the equations, the interpretations and the specific measurement and weighting techniques. Please ask if you need additional information.
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We have been monitoring a temperate lake during the winter and observing Daphnia under the ice, when normally they would not be found in the water column. Some of which still have asexual eggs.  The system is hyper-eutrophic which is leading us to think perhaps food conditions still permit growth even though temperature is cold. 
Has anyone else observed Daphnia in winter or under the ice in lakes? Thanks.
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Hi Brian
There is some literature also from other counties on daphnids spending the winter as adult females. For instance, Larsson & Wathne (2006) reported adult females during winter in oligotrophic mountain lakes.  They claimed that females that produced ephippia in the autumn have less reserve energy at that time, than those  spending the winter as adults. Furthermore, Lampert et al. (2010) hypothesized that females can exhibit a mixed strategy, first produce ephippia, then spend the winter in an active state. Hamrova et al. (2011), however, found strong clonal variation among populations regarding their reproductive strategy during unfavourable conditions. Thus, high food density appears not to be a prerequisite for adult females under ice in winter, but perhaps rich winter conditions may improve the survival of the adults during winter. Larsson & Wathne (2006) reported high mortality towards the end of the winter in oligotrophic, alpine lakes and assumed that this is due to lack of reserve energy in support of your hypothesis.
References
Hamrova et al. BMC 2011 11:231
Larsson & Wathne (2006) Arch Hydrobiol 167: 265-280
Lampert et al. (2010) in oligotrphic mountain lakes. Limnol. Oceanogr., 55(5): 1893–1900.
Bror
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I need some information about present situation of Gammarus species in aquaculture industry and their economy importance.  
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You may ask Dr. Lyudmila Litvinenko g-r-c[@]mail.ru from the Laboratory for commercial invertebrates of the Fisheries Center (Tyumen, Russia) 
This Center has experience on your question in relation to Gammarus lacustris
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Though i am working on fish from past few years, presently i have shiftd my focus towards aquatic plants. In this connection, I want to conduct a growth studies as well as effect of differnet manure on various aquatic spp. 
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thank you to all
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with reference to extreme weather events
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In our country the fisheries policy maker,of course talk about climate change but no such research work has been initiated so far. From my experience of about 38 years. In tropical and temperate aquaculture I found shifting in seasons, rise in average air and water temperature by 2_4.1 *c. And found different growth behavior of a species. For example, To purifiers distributed between 600 _ 18ok m ask but now the range has changed from 800- 2100 m ask ie  attitudinal changes owing to change in temperature and other parameters. I have introduced craps- indian and Chinese  in Himalayan ranges and have developed a altitude base composite carp farming system taking into account species, density, ratio, growth  vs.  Temp. Oxygen ,feed quality and quantity, husbandry practice etc.. with data, I have noticed climate impact on craps and clearly indicate to change our programme of aquaculture suitable to different geographical and climatic zone
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To be applied to aquaculture. The largest I've found in the literature is 10L for this species. 
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I regularly culture larvae of Evechinus in 20 litre plastic buckets at reasonably high density (>10/ml) for bulk samples needed for proteomics without problems such as raised above.  We use a aeration system modified from Mike Russell's one in green sea urchins to be static.
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I would like to connect with some researcher with a view to obtaining information.
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Maybe this PhD-Work is helpful:
Best regards,
Mike
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Organic shrimp farming is not fully stable in Vietnam. I am very much interested to see how organic aquaculture has developed in the world. 
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Hi Van To,  I could see a number of full-text papers in Scholar Google. Please try with your keywords and I am sure you will get sufficient papers on the demand of organic aquaculture products. Regards
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For the recommended water quality parameters (DO, salinity, alkalinity, and others) for shrimp (L. vannamei or P. monodon) is used as the fixed parameters during a crop.
Based on experience/research/papers. Does anyone know about the specific water quality parameters (DO, salinity, alkalinity, and others) for the specific stage of shrimp culture? For example, how about the optimal water quality parameters for the first 30 days of culture, for the period between day 30-60 of culture crop and continue until harvest?
Thank you very much for helping.
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I want to compare my result with standard water quality parameter for reference point of view i need the information.You can suggest if you did research practically. Thanking you Regard Brijesh 
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L. vanamei can withstand all salinity from 0.5 to 40ppt, however good result in lower salinity if minerals required opted.
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Dear Researchers
I had 3 data group. environmental data (Temperature, Oxygen, pH, EC and Turbidity), zooplankton community and growth rate of a fish. All data belonged to a one pool. Now I tried to find a best model to describe the relationship between number of zoopnaktons, environmental data and growth rate of the fish. what is best statistical method? Is GLM applicable?
Thanks for your help 
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Heiarchial cluster analysis, component analysis can be done to study the direct and the indirect interaction and interrealtion between the zooplankton community and the fish growth rate.... SPSS and SYSTAT can be used for the same...
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I do have papers from the USA and Canada, however I am looking for other parts of the world where shellfish aquaculture is present and thriving such as China, Spain etc..
Cheers, Remi
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Merci beaucoup Dr. Cresson !
Thank you very much for this literature. 
Are you latter comment, you are actually right. Here on the Canadian east coast we do find important biomass of picophytoplankton in rather small estuaries dominated by shellfish aquaculture. This said, those estuaries are enriched with important nutrient loads from runoffs (agricultural fields, golf courses etc...) promoting fast turnover for fast growing phyto like picophytoplankton. 
Really appreciate your time on this request!
Remi
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I am undertaking my thesis research onshrimp culture using the new biofloc technology. How do I set up a new biofloc system? Anyonewho can assist me with literature and videos on how to set up a biofloc system? 
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Hi Simon, please visit this link https://www.facebook.com/AARM.AIT , you will find three videos on Success story for biofloc technology on farm demonstration trial at M/S Hitde Seafarm, Mahendrapalli, Kattur Nagapattinam district, Tamilnadu, India. All the Best.
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Most of the papers I read said that they've done 3 months feeding period to test the experimental feed to the fish fingerlings. What is the significance for this 3 months period?
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I assume it also depends on the fish species and growth. A doubling or tripling of the biomass could also be a good parameter. As for catfish a 3 months period is very long and biomass will go x 10 or more, getting interfering parameters as canibalism, density but also other feed needs and composition.
Regards,
Caroline
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Mainly from EU regulations and directives, or from FAO guidelines.
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There are various reports mentioning maximum Cr soil content of 500-2800 ppm.
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Dear Friends, I am trying ECOSYSTEM based modelling of Zuari Estuary (Goa, Southwest coast of India) with about 24 ecological groups. The basic inputs were provided and the model was mass balanced (adjusting the biomass of four groups) with Eco trophic efficiencies were kept under one. However, the respiration values are showing negative values and it is given as an error in result display. How should i adjust the input data (Diet matrix or Biomass which has to be adjusted) for making the respiration values to positive and within one.
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sorry for saying that, but are you sure that that approache is  really useful?   Despite of the use (and misuse) of  that models, do they really say something to us?  Despite of the overhelming number  of papers about do they really im,prove the quality of our comprehension???  An example :10 % of energy transfer from one "trophic" level : as reported in many books  (e.g. Colinvaux) the rule of 10% widely applied has no  scientific support  and the passive application did serious damage in agricultural  plans in the so called " developing world". There are heavier  problems (if possible)  on fisheries models  but nobody seems to care 
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We're doing a research on the effects of WSSV on Penaeus monodon species cultured in the Philippines. 
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Importance of fish microbiota
External mucus secretion cannot be studied independently
to the general health status of fish. Indeed, fish
health is strongly dependent on the internal microbiota
which helps in nutrients uptake and protect fish from
pathogenic invasion (Ringo et al., 2000; Makridis et al.,
2005). Adhesion capacity and growth on or in intestinal or
external mucus has been demonstrated in vitro for fish
pathogens like V. anguillarum and A. hydrophila (Garcia
et al., 1997; Krovacek et al., 1987) and for candidate
probiotics such as Carnobacterium strain K1 (Jo¨born et al.,
1997) and several isolates inhibitory to V. anguillarum
(Olsson et al., 1992). In one of these studies, the aim was to
measure the in vitro capacity of the strains to adhere to and
grow in turbot intestinal mucus in order to investigate
their potential to colonize farmed turbot as a means of
protecting the host from infection by V. anguillarum
(Olsson et al., 1992). The intestinal isolates generally
adhered much better to a film of turbot intestinal mucus,
skin mucus, and bovine serum albumin than did V.
anguillarum, indicating that they could compete effectively
with the pathogen for adhesion sites on the mucosal
intestinal surface (Verschuere et al., 2000). Mechanisms
that may be implicated include the production of antimicrobial
substances such as organic acids or bacteriocins,
competition for nutrients or adhesion receptors, inhibition
of virulence gene expression, and enhancement of the
immune response (Balcazar et al., 2007).
 Inhibitory compounds present in fish mucus
Depending on several factors, such as the fish species,
health, environment, mucus origin and microbiota colonizing
the mucus, many types of interaction could be
implicated to prevent pathogen infection. It is important to
take into account that, additionally to the immune system,
fish have a bacterial community that can inhibit the
adhesion or the development of pathogens. Effectively,
some bacteria produce inhibitory compounds, particularly
in the digestive tract, and may be responsible for
controlling the colonization of potential pathogens in fish
(Ringo et al., 2000; Makridis et al., 2005). For example a
Vibrio sp. recovered from the intestine of a spotnape
ponyfish (Leiognathus nuchalis) in Japanese coastal waters
inhibited the causal agent of pasteurellosis/pseudotuberculosis,
i.e. P. damselae subsp. piscicida. Specifically, the
inhibitory compound was heat-labile and proteinaceous,
with a molecular mass of <5 kDa, and was considered to be
possibly a bacteriocin or a bacteriocin-like substance
(Sugita et al., 1997). Similarly, some bacteria, isolated from
the digestive tract of halibut (Hippoglossus hippoglossus)
larvae, were found to be capable of inhibiting growth of
pathogenic Vibrio sp. (Bergh, 1995). All these bacterial
strains were Gram-negative rods, most of which were
fermentative and produced catalase and oxidase (Austin,
2006).
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Some published literature gives examples of tray-type cage that uses a small mesh size as the floor and a larger mesh size to make up the walls and roof. I have not found examples of this design being used at large scales. 
Another option is to use abalone-type cages. 
Does anyone have further ideas for suspending specifically sea-cucumbers?
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To Mr. Wartenberg
Dr. Yokoyama has written about polyculture With Fish and sea cucumber.
Dr. Pitt and Dr. Nguyen at the Research Institute for Aquaculture in Viet Nam has written about both mono- and polyculture regarding sea cucumber and shrimp/ Babylon snail.
I suggest you to read these articles, and perhaps contact them for further communication regarding polyculture and sea cucumber.
References:
Pitt and Nguyen (2004) Breeding and rearing of the sea cucumber Holothuria scabra in Viet Nam. In: Advances in sea cucumber aquaculture and management (eds: Conand, Purcell, Uthicke, Hamel, Mercier), 333-346.
Yokoyama (2013) Growth and food source of the sea cucumber Apostichopus japonicus cultured below fish cages — Potential for integrated multi-trophic aquaculture. Aquaculture, 372-375.
Kind regards, Halldis Ringvold
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I am looking for out-door aquaculture technique which takes advantage of gravity so as to conserve energy inputs. Are there such techniques available, I am particularly interested in algae. Any comments in this aspect is highly appreciative.  
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Yes, many outdoor systems utilize gravity to minimize energy inputs. The only drawback is that these systems tend to be flow-through. For example, some freshwater ornamental aquaculture farms are sited on the sides of hills or mountains below natural springs. Water is channeled from the spring through the farm and flows via gravity through ponds, raceways or other culture systems and is then released into water treatment ponds sited at the lowest point on the farm. The water is then  evaporated or treated and released. Gravity-fed flow-through may be good for macro-algae, but would be impractical for micro-algae given the difficulties of retaining microalgae within your culture system. 
A method that may be applicable in recirculating microalgae culture systems would be airlift - pumping air into the water as a method for lifting water. A basic explaination can be found here:
Air pumps can be more energy efficient than water pumps in some situations, but this will depend on the size and requirements of your system.
The best way to reduce energy costs in any recirculating system is to minimize head height - the difference in height between the lowest point in the system and the highest. For example, using gravity to return water from a header tank or filtration system held above a culture tank still requires the water to be pumped against gravity to the height of the header tank/filtration system. In contrast, using a filtration system that sits only slightly above horizontal with the culture tank minimizes the height that water must be pumped against gravity.
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In case of commercial fish farming poly and mono-culture (carp, tilapia, pangus, catfish, or exotic carp). How does species selection (eg. size, ratio, species, seasons) and crop rotation affect the productivity and growth of fish in commercial farming? 
Please don,t hesitate to explain in detailed. Thanks in advance.
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Cmercial farming basically depend on breed(genome),seed(quality,no./ m,size),feed(ingradients,quantity,frequency of feeding)huzbandady practices(intensive,semiintensive,extensive,integrated with crop,/livestock/etc) and ofcourse optimum level of water quality6
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the idea is to evaluate the limit for shrimp aquaculture growth in coastal systems (lagoons, estuaries), based in their size, nutrients loading, type of aquaculture system (extensive, intensive, hyperintensive) or any other indicator
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Hi Arturo, I'd suggest that you look at the productivity and other data on lagoons more or less similar to your own. You'll probably arrive at a range "from to". It would give you an idea, and for practical reasons and until you have applied the models and other scientific means, also a practical guidance.      MB-Y 
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Transportation of brooders or seeds (egg,fry, larvae) is very critical in aquaculture process. Due to poor managing practices mass mortality can be happened during transportation. What are the parameters to be monitored or measured during (before or after) transportation of fish?
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Dear Mohammed Mosarof,
Thanks for your reading materials and thanks for the other researcher's answer too.
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with reference to Indian Major Carp culture.
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Dear, 
We know that the water footprint of an individual, community or business is defined as the total volume of freshwater that is used to produce the goods and services consumed by the individual or community or produced by the business. 
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using only ground water, with reference to growth.
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Dear Researcher R. K. Mohanty,
Yes I can share my experience. I gathered some Thirteen (13) months of practical work experience as Junior Consultant (Part-time) starting from 01 July 2009/ 23 August 2010 in a fish farm namely Noakhali Integrated Agro Industries Limited (NIAI Ltd.), Sonapur, Noakhali Sadar, Noakhali, Bangladesh. In NIAI Ltd they rigorously used underground water for fish farming ad hatchery operation and many times they suffer from low dissolve oxygen (DO) and or even excess iron (Fe) in water. However, would you please explain or specify actually what kind of information you want to know. 
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Why has seed production of portunid crabs (Scylla serrata& Portunus pelagicus) not reached commercial level on par with penaeid shrimps?
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The biggest issue with crab aquaculture is cannibalism; crabs eat each other at a much higher rate than shrimp do, and unlike shrimp, making sure they have adequate food doesn’t usually solve the problems.   I’ve worked with blue crab (Callinectes sapidus) and now red king crab (Paralithodes camtschaticus) and in both species you can see around 50% mortality at each molt (when raised in captivity), mostly due to cannibalism.  In addition, the market size for crabs is much larger than for shrimp so it generally takes longer for them to reach market size (which increases costs considerably).  You can reduce cannibalism by reducing the density of the animals or by rearing them in individual containers but that, of course, is a very expensive way to rear them.  There is some potential for doing stock enhancement (releasing hatchery reared juveniles into the wild to supplement wild stocks) but the economics of that (who pays for it) gets a bit trickier.  Those are some of the issues. 
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With reference to inland aquaculture.
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The potential to increase aquaculture production by expanding the present pond area and raising water consumption is limited. Consequently, the most sustainable way to increase aquaculture production is through intensification of existing aquaculture systems with emphasis on BMP, Restricted feeding protocol triggering compensatory growth using floating feed for improving water quality, Increasing pond productivity through biofloc technology, Enhancing nutrient utilization .
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Please provide information on research status on multitrophic aquaculture system. m.
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Integrated Multi-Trophic Aquaculture is the farming of different aquaculture species together in a way that allows one species’ wastes to be recycled as feed for another. Farmers combine fed aquaculture (e.g., fish, shrimp) with inorganic extractive (e.g., seaweed) and organic extractive (e.g., shellfish) aquaculture to create balanced systems for environment remediation (biomitigation), economic stability (improved output, lower cost, product diversification and risk reduction) and social acceptability (better management practices).
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With reference to pond culture.
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Biofloc technology (BFT), is the best way for microbial control of water quality within the pond. The basic principle of biofloc technology (BFT) is the retention of waste and its conversion to biofloc as a natural food within the culture system. This is done by constant aeration and agitation of the water column and addition of carbon sources as organic matter substrate to allow aerobic decomposition and maintain high levels of microbial floc in suspension in fed and/or fertilized ponds.C:N ratios N10:1 is optimal for optimizing biofloc production while minimizing ammonia regeneration.
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I try to identify this species but in sequentiation analysis indicate that is M. sallei but morphological is similar to M. leucophaeata.
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Hi Jeffrey
I cannot clearly see the apophysis in your images, but if your specimens still have it the size and shape of this protrusion in diagnostic in the Mytilopsis group.
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During shrimp pond drainage.
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Dr. Mohanty
As the flow rate while draining a pond water will vary over time (i.e., during the draining period) due to decrease in hydraulic head of the pond, discharge-cross section-time method will be an approximation only for determining flow velocity. Hence, easy and accurate measurement can be made through use of digital flow meter.
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for coastal shrimp farming
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Based on my own experience for Odisha climatic condition and coastal soil type, P. monodon and Litopenaeus vannamei culture is most suitable.
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In GIS which model is most suitable for site selection of aquaculture ponds?
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Dear Ram; you can check fao website. There are lots of information about your question in FAO website.
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I am thinking of including it as an ingredient in an experimental aquarium diet.
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Carotenoid content based the culuring system and condition. Results from different conditipn is not a good reference for any trial, please find out your culture system similar with any researcher or institute or not, may be in your country. But to make sure, your analyze or sending the sample to the lab. If you want to conduct a trial aimed for publication, analyzing first is intensively recommended.
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I try to control algal blooms in fish farms using rice straw. Which of the different released substances from rice straw, and how can I analyze it?  
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Yes, leaves, stem etc., if you think that they had different concentrations.
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Dear all,
I have been trying to find out what company/research center that may be able to provide nauplii of white shrimp (L. vannamei) in the US for my research.  I have contacted Hawaii and Florida with no luck so far.  If you have any contacts that I can connect to, it would be much appreciated
Thank you very much in advance.
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Shrimp Improvement Systems is just one of a number of companies that can supply broodstock and PLs in the USA.  They have operations in Hawaii and Florida.
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We want to know if there are different effects in feed consumption of Leucaena leaf meal inoculated with B. circulans extracted from the soil and B. circulans extracted from the gut of Labeo rohita (rohu). 
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Hi Jude,
B. circulans may be the act as good probiotic by the nature of hydrolysis of starch, gelatin, beta galactosidase etc... hence the Leucaena leaf meal inoculated with B. circulans is good probiotic nature than the gut isolated B. circulans due to poor decomposition of casein.
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What are peoples perception about Total Quality Management in relation to Aquaculture production?
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The total quality management in relation to aquaculture production is similar to the quality control of any bussiness,it is checked that all parts of the production process work properly and have not been altered bye human or environmental inlfuence. For example in the case of maintaining water quality, is expected to deteriorate over time either bye the uneaten food, animal faeces and other organic matter wich can promote the growth of harmful bacterianes communities, in this case you should handle the water quality factor sampling, analyzing, identifying the problem and implement corrective measures so as to follow a constant monitoring. Among other factors of production system are the feds and feeding, the environmental conditions, seed quality, supplies, equipment and even the market conditions.
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The motive is to develop spatial planning tools to support the ecosystem approach (considering bio-physical and socio-economic factors, suitability of cultured species, scale of operations and farming technologies employed) to aquaculture and fisheries development. But, as a beginner, I would like to know what are the spatial planning tools widely used in these kind of research. Any kind of help is greatly appreciated.
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The Ecosystem Approach to Aquaculture (EAA) is Participatory in nature with multiple objectives interwoven with other sectors and nested with adaptive capability using extended knowledge, incentives and open public participation and transparency as the cohesive force for stakeholders.
Considering spatial scope, it covers the farm, waterbody and the global scale.
EAA starts from site selection through operation and final marketing of products. To ensure that the environment is protected, decision making and modeling tools come in handy. Decision support for expansion and optimization of aquaculture operations can make use of a wide range of models, designed and run in the virtual environment with field mverification as the final step.
Environmental Models
Mass balance equation, which can be used for many different parameters but is most widely used in a water quality context to model nitrogen and phosphorus concentrations in and from aquaculture systems.
DEPOMOD: can be used in local-scale assessment of the effects of fish cages on the environment.
Spatial Models
GIS is an important tool in this regard because it organizes, analyses and presents geographical data in a useful and efficient manner via standard data formats.
You can visit:
This gives you a general look at the EAA tools for Aquaculture and freshwater at the bottom page. You can then navigate to the three websites given there. Particularly, the ECASA toolbox: http://www.ecasatoolbox.org.uk/the-toolbox
There is a list of indicators and models to choose from. However, I would suggest you start by looking at this site: http://www.ecasatoolbox.org.uk/
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With reference to semi-intensive shrimp farming. Thank you.
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Through phytoplankton bloom the secondary productivity that fin fish culture and shell fish culture can be increased. Iron fertilozation of ponds can increase the phytoplankton productivity.
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I want to quantify stress levels in noble crayfish (Astacus astacus), kept in different light conditions. Most studies on crustacean stress seem to focus on the effect of acute stressors. Can anyone suggest physiological parameters in hemolymph or tissue that indicate chronic stress?
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To Mr. Abeel
You may try Prof. John Benzie at University College Cork. He has been working on marine Crustacea (Tiger Prawns). I assume he or someone in his team might guide you further. Please send him my regards.
Kind regards, Halldis Ringvold 
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For artificial shelters (reefs) which materials (wood, concrete, plastic tube, pvc) are more friendly or familiar with environment? specially for crayfish.
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Thanks dear Peter (my good friend).
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Could you please tell me in maximum range for intensive culture how many fish like Cyprinus carpio (common carp) or Oreochromis sp. (tilapia) can be used in a square meter?
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Depending upon growth rate,which is a function of the parameters as stated above, usually 10 t0 15 thousand fingerlings are added per hectare of a culture pond,which are usually 3 to 3.5 feet deep.That comes to 1 to 1.5 fish per square metre. A fingerling is almost 4" size.Both the fish varieties being benthic feeders,it's possible that the O2 levels would be lower in those waters,& depending upon water temperature & surface winds, it would be advisable to go for slightly lower values for stocking.
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I've encountered several journal articles and studies that show aquaculture water quality is not usually studied on its own and the studies show results are tied to specimen immune response. 
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Hello,
Your question is not clear. Water quality in aquaculture should be monitored for any species because it affects fish performance (growth, immune, reproduction). You can monitor water quality in a study without biological assays such as immune response and ...
This type of work is in the field of chemistry (water chemistry). You can, for example, check the form of toxins (e.g. copper ion) under different water qualities (e.g. pH, hardness, ions ...). In this work, although you do not have biological assays (e.g. immunity), but the work is conducted to find the effect of water quality on the formation of different copper ions which have different toxicity. Accordingly, differentiation in toxicity is studied because of its effect on biological indices (such as immunity).
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If so, does it result in fungal contamination of the system?
We started feeding Liquifry and the other empty tanks started to have fungal growth. Was wondering if anyone had any experience with this. Thanks!
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Thank you all for your reply. Will definitely stop feeding Liquifry.
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If you have any experience (or know someone who has it) in the production/reproduction of Atractosteus tropicus, and want to share it, I will thank you a lot.
There is a little literature about it, but I want to hear field experience about the environmental, nutritional and management requirements of this fish.
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Hola!! Aca en la UNA, el compañero Adrian Sevilla (Estación Experimental 28 Millas, Limon) ha tenido experiencias de producción. Hicimos varios levantes de semilla con los colegas de la Universidad Autonoma de Juarez, Tabasco. Además, el colega Maurizio Protti tambien participo en los levantes aca en CR, aunque ahora el esta pensionado.
Saludos
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Barnabas (1980) proposed a system for collecting zooplankton in lagoons using autonomous and stationary devices, for which I tried to estimate the cost of installation, but would there be another way that is more efficient?
The complete reference of Barnabé is:Barnabé, G. (1980). Système de collecte du zooplancton à l'aide de dispositifs autonomes et stationnaires, in: Billard, R. et al. (1980). La pisciculture en Etang. pp. 215-220
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Most of the zooplankton are phototrophic, so they are attracted to a light source. You can use a light source   to amass them around the light source at night, then you can use a pump to filter the water on a fine mesh collector and collecting the zooplankton. But most of them will kill, anyway, I think  it is worth to try it.
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Some culturists collect feral fingerling marine fishes to be cultured. The isopods have been transferred from feral fish to the farmed fish or to fishes in open lakes.
I need to know how to control this mistake in transport in new situations.
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Thank you for your interest, but the parasite transport to a large natural closed lake more than 55 000 acres , you mentioned treatment is difficult to apply.
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My name is Maria Rousou, I am a biologist working at MER Lab Ltd in Cyprus (www.merresearch.com
I would like to ask for your guidance and advices regarding the open-sea aquaculture annual emissions estimation in coastal water.
According to the Regulation (EC) No 166/2006 of the European Parliament and of the Council concerning the  establishment of a European Pollutant Release and Transfer Register and amending Council Directives  91/689/EEC  and  96/61/EC” (the  ‘E-PRTR  Regulation’), fish farms with production capacity of more than 1000 tonnes of fish or shellfish per year need to submit to the National authorities their annual TN, TP and TOC releases in sea water.
The E-PRTR guidelines and references cited within, state that the annual TP and TN emissions can be estimated by using the mathematical formula
L = 0,01 x (ICi - PCf)
L       :  phosphorus (P) or nitrogen (N) discharge to water body (tonnes/year)
I        : feed used (tonnes/year)
Ci      :  P or N content in feed (%)
P       :  production (tonnes/year)
Cf     :  P or N content in produced organisms (%)
For the TOC determination (as Total C or COD/3), the guidelines state to carry out water analysis following ISO 1484:1997.
However, no further information is provided on how frequently the samplings should be and how to use these snap-shot data to determine the TOC annual emissions in sea water. Using the mathematical equation stated above without validation could lead to over or underestimation of emissions.
Do you have any guidelines/advises on possible ways to determine fish-farm TOC annual emissions releases in seawater?
Please keep in mind that the regulation requests that the estimations must be done at lowest costs.
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Leave it to bureaucrats to specify equations that don't capture the real mass balance and environmental issues. 
For example, N isn't conserved.  Any SS (manure) going to the bottom can crate low ORP conditions and mineralize to ammonia.  This can then be oxidized to nitrite then utilized by anammox bacteria that live on ammonia + nitrite to N2 gas (lost of N) -- common in marine sediments.  Of course any nitrate can also be loss to pure denitrification in the sediments while suppressing H2S formation.  
Carbon will be very difficult or impossible to measure.   In most net pen operations, the flow through the net pen has to be high enough to prevent big O2 swings (especially with tidal current variations that go to zero flow), which means that the feed to flow ratio has to be in the low mg/l range.   From a kg of feed into the fish, you get about 0.2 kg of manure (dry) which can then be converted to soluble BOD on the bottom with a many months time scale.   But that soluble BOD will be oxidized in or near the bottom.   Microbiological ecologies evolve and change to use that food as fast as it comes in.  
The fraction of manure that is soluble BOD or soluble TOC is relatively small.  Remember, the potentially soluble and easily digested (mineralized)  components of the feed were digested and converted into CO2, H2O and fish biomass.   With the soluble and insoluble TOC from the net pens rapidly separating, what the local currents are and the amount of local turbulence and vertical mixing will determine your sampling results.  On top of that, with the low feed/flow inputs will put you in the noise of baseline natural TOC and BOD in ocean waters (background is higher in bays, etc.).   Sampling is probably a waste of money.
The soluble BOD from fish would be in <3% of the feed input range (ie. > 80% of the TOC is in the manure SS insoluble fraction), for many fish feed diets.  This is what I have seen in recycle systems where you eliminate most of the SS from the waste water then oxidize the BOD and ammonia (this is based upon having the solids mineralize for a variable time period of 1 to 7 days with the solubles generated going into the water column).   However, that data would be for BOD30+, not the standard BOD5.  With most of the manure containing more refractory polymers like cellulose and other low digestibility components along with much of the ash, most BOD5 testing isn't enough time for decomposition.  This is why the BOD/TOC (mentally correct that ratio for BOD being O2 and TOC being CO2 based measurements) ratios on the waste are relatively small.  
If the SS is going into the sediments, you probably have sediment traps.  The flux of the SS into the sediments and the mineralization of those solids will release the P into the sediments.  Being concentrated in the sediment will result in high local P concentration which will start to diffuse out of the sediments, meanwhile Ca and F from the seawater will diffuse in creating a chemical reaction to form phosphate rock (very insoluble precipitate) which becomes biologically unavailable to the ecology.  Another  loss, but this requires that the SS flux to the bottom be higher than the regulators probably want and will create a decrease in the ORP and decrease in the H2S boundary layer.   This is how some natural phosphate rock deposits were formed with high dead algae flux into the sediments, like is naturally occurring both in the Gulf off of Mississippi and off the coast in Santa Barbara area of California. 
For just a simple minded ball park number of both soluble and insoluble TOC and not caring about the fate or significance or impacts of the TOC (as carbon), a good guess would be about 0.2 * 0.5 (carbon/dry organic manure) * (1 - .25 (% ash in manure)) or about 7.5% of the feed.   Most of this TOC will be refractory and not show up as BOD5.  
There is a lot of information relevant to these microbiological processes and mass balances in the aquaculture literature like P and SS in trout raceways and N in recycle aquaculture systems.   
When the regulators have good estimates of the amounts emitted from the pens, how will they be wise enough to rationally use that information?  Unless your regulators are a lot smarter than those in the US, they will be clueless and really make arbitrary decisions based upon political considerations and activist group pseudo-science. 
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I am trying to evaluate the amount of MT which could be used as a minimal single dose/amount required per day to each fish to have an effect on sex reversal. What is a minimal amount of MT per fish to effect the sex reversal?
In the mixture of feed and hormones, how does this hormone attach to the feed after alcoholic evaporation? Is there any bonding?
Also, I would like to know the mechanisms of effects once the hormones enter the blood stream, where is it acting?
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Hi Desmond.  I said DHEA was better not because it is better in reversing sex than testorsterone but because it has an equivalent effect on sex reversion, growth and feed conversion without the higher expense and threat to the environment associated with the use of testosterone.  Please see the paper at the link in my first answer. Thank you.
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For many reasons, for walleye larvae production, we need to increase light scattering effect in the tank water column. This is actually possible by adding suspended solids like clay, resulting in an increase in turbidity and therefore in light diffusion in the water column. However, this addition of clay causes some filtration problems in a recirculating system and it's why I'm looking for an alternative idea : dissolved matter like dyes? Mirrors setup? A kind of screen over the tank ? Special light diffuser?
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I would be concerned about the possibility of lipid products interfering with swim bladder inflation in tank culture of walleye larvae. I think an algae product (live algae, algae paste, or even Spirulina powder) may be better - I have used these in flow through tank culture of walleye larvae to produce turbidity and normal spatial distribution of the fry (to keep them off the sides of the tank). I have also used algae products in marine  larval fish culture.  Algae products should not be a problem for recirculating culture systems.
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Is there any other methods except Bomb Calorimeter for finding the amount of energy in diet?
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You can use bomb calori method for the same.
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I've put a drop of water from the bed of my walleye larvae tank under the microscope at 400X and i've seen these rod-like bacterias. By its shaking mouvements, do you think this is Flexibacter columnaris (see the video : http://youtu.be/SYH4wZCw8wM) ? This is not appear to be "flexible", so I guess it's not. I've no sign of disease on fish for the moment. The bacterias seems to feed on food residue. (Freshwater: Temperature = 18°C, [O2] = 8mg/L.)
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ıt is not possible to identify by the looking a bacteria but morfologicaly and movement style not similar to Flexibacter columnaris.
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Sustainability is a word constantly being used in describing various aquaculture systems, defining goals for aquaculture etc, but what does this really mean? Does it demand no environmental impact, or no net energy usage, or no fish-based feed ingredients, or what?
It seems to be the favorite phrase by politicians and legislators, and we scientists use it constantly as well, but what do we really mean when we use it?
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Dear Catarina,
Thank you so much for a thorough and highly informative responses to my question. Instinctively, I feel that the terms "social and environmental responsibility" are in some ways more tangible than "sustainability" and thus of greater help in setting concrete goals for aquaculture operations.
A point in case is the slave labour used by the Thai seafood industry as just revealed by The Guardian http://www.theguardian.com/global-development/2014/jun/10/supermarket-prawns-thailand-produced-slave-labour. The prawn production itself may be environmentally sustainable, but it's certainly not socially acceptable.
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Offlavor is a big issue in fish marketing and caused by many reasons such as geosmin from filamentous bluegreen algae, benthos, pollution etc. Consumers don't prefer such fish and as a result, producers lose market. There should be a way to solve this problem. Can anyone make any suggestions?
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The most common off-flavour compounds found in cultivated fish are 2-Methylisoborneol (2-MIB) and geosmin (GSM) (caused by microorganisms such as cyanobacteria- Anabaena spp, Microcystis spp., Oscillatoria spp etc). Due to their high bioaccumulation rates in lipid-rich tissue, even very low concentrations of 2-MIB and GSM in the water can cause an undesirable earthy-musty smell and taste in fish flesh. Purging is still the only reliable, and economical way to remove off-flavour (by moving the fish to clean, odour-free water for a certain time prior to harvest). A recent research reported that earthy and musty offflavored Atlantic salmon containing lower concentrations of geosmin and MIB need to be placed into a system containing water that is both geosmin-free and MIB-free, either recirculating or flow through, for at least 10–15 days to achieve the greatest reduction of the bioaccumlated off-flavor compounds in the fish flesh. Other studies such as with tilapia were found to require 16 days of depuration in “clean” (odor-free) static water to eliminate geosmin from the muscle tissue. For channel catfish, the depuration periods of 13 and 21 days were reported for geosmin and MIB respectively. Aquaculture producers may like to apply algicides such as copper sulfate and/or diuron to the ponds to reduce the abundance of the odor-producing cyanobacteria as well!
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I would like to verify if adjusting the pH of the water in an emptied Salmon RAS will successfully kill saprolegnia zoospores. Our plan is to adjust the pH to 13, does anyone have any information whether this is sufficient or if there are more suitable alternatives. Thank you.
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I know that in traditional fishery(ponds) usually used lime for rising pH as a prevention Saprolegnia.It has to work.Also Effect of many treatments depends on its duration.You have to check it and impact of high level of pH on equipment in laboratory
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