Juvenile productionJuvenile product

Juvenile production

Juvenile production and grow-out to market size are managed separately, although both are performed in earthen ponds. A managed juvenile production programme is essential to provide the advanced juveniles required for grow-out, and to make effective use of the superior broodstock selected. Depending on temperature and whether berried females or mature broodstock are used, a culture period of 3 to 4 months is necessary to achieve a mean size of juveniles of 5 to 15 g. The two most critical factors in juvenile production are the provision of shelter and food. The general management of juvenile rearing ponds is the same as that described in this fact sheet under ongrowing techniques.

Typically juvenile ponds are stocked with mature females and males at a ratio of 4:1 and a density of 1 500/ha, carefully selected as the best of the stock available from grow-out harvest. Under well managed conditions, 50-100 advanced juveniles will be produced per broodstock female, providing a yield of 60 000 to 120 000 juveniles/ha.

At water temperatures above 25 ºC, a juvenile production pond stocked with male and female broodstock is ready for harvest in four months. Alternatively, when berried females are stocked, the juvenile production pond is ready to harvest in three months. To maximise survival and growth of the juvenile redclaw, an abundance of shelter in the ponds is essential. This is usually provided in the form of bundles of synthetic mesh, tied onto a line with a weight at one end and a float at the other. Arranged in this manner, these bundles extend from the pond floor up into the water column providing many spaces and surfaces for the juveniles to utilise. These mesh bundles are stocked at one every 5 m2.

Juvenile production ponds are carefully managed to provide an abundance of planktonic organisms which the juvenile crayfish utilise as food. The planktonic organisms include both phytoplankton and zooplankton; it is primarily the latter that are consumed by the juvenile crayfish. As they grow, they progressively consume less plankton and more of the detrital food that occurs on the surface of the shelter material and, more especially, on the mud surface.

Maintaining high levels of plankton involves regular checking of water quality and periodic fertilisation of the water with nitrogen and phosphorus (typically diammonium phosphate at 50 kg/ha).

Harvesting of the juveniles is achieved by a number of methods. Sometimes individual mesh shelters are removed and the juveniles shaken out. However, the most effective method is to employ a flow trap. With this method, the pond is completely drained and all the crayfish are attracted into a trap. From there they can be removed to tanks and sorted, counted and then stocked into the grow-out ponds.
Ongrowing techniques
Although all commercial redclaw grow-out occurs in earthen ponds, there is some interest in tank culture.

Ponds

Redclaw aquaculture, both in juvenile and grow-out ponds, is performed in earthen ponds, typically 0.05 to 0.5 ha, with a depth of 1.0-2.5 m and a V-shape that allows rapid and complete drainage. Water is sourced from surface supplies or underground and should have a pH of 6.5-8.0, hardness of >40 ppm, and low levels of salinity (

ผลลัพธ์ (อังกฤษ) 1:

Juvenile productionJuvenile production and grow-out to market size are managed separately, although both are performed in earthen ponds. A managed juvenile production programme is essential to provide the advanced juveniles required for grow-out, and to make effective use of the superior broodstock selected. Depending on temperature and whether berried females or mature broodstock are used, a culture period of 3 to 4 months is necessary to achieve a mean size of juveniles of 5 to 15 g. The two most critical factors in juvenile production are the provision of shelter and food. The general management of juvenile rearing ponds is the same as that described in this fact sheet under ongrowing techniques. Typically juvenile ponds are stocked with mature females and males at a ratio of 4:1 and a density of 1 500/ha, carefully selected as the best of the stock available from grow-out harvest. Under well managed conditions, 50-100 advanced juveniles will be produced per broodstock female, providing a yield of 60 000 to 120 000 juveniles/ha. At water temperatures above 25 ºC, a juvenile production pond stocked with male and female broodstock is ready for harvest in four months. Alternatively, when berried females are stocked, the juvenile production pond is ready to harvest in three months. To maximise survival and growth of the juvenile redclaw, an abundance of shelter in the ponds is essential. This is usually provided in the form of bundles of synthetic mesh, tied onto a line with a weight at one end and a float at the other. Arranged in this manner, these bundles extend from the pond floor up into the water column providing many spaces and surfaces for the juveniles to utilise. These mesh bundles are stocked at one every 5 m2. Juvenile production ponds are carefully managed to provide an abundance of planktonic organisms which the juvenile crayfish utilise as food. The planktonic organisms include both phytoplankton and zooplankton; it is primarily the latter that are consumed by the juvenile crayfish. As they grow, they progressively consume less plankton and more of the detrital food that occurs on the surface of the shelter material and, more especially, on the mud surface. Maintaining high levels of plankton involves regular checking of water quality and periodic fertilisation of the water with nitrogen and phosphorus (typically diammonium phosphate at 50 kg/ha). Harvesting of the juveniles is achieved by a number of methods. Sometimes individual mesh shelters are removed and the juveniles shaken out. However, the most effective method is to employ a flow trap. With this method, the pond is completely drained and all the crayfish are attracted into a trap. From there they can be removed to tanks and sorted, counted and then stocked into the grow-out ponds. Ongrowing techniques Although all commercial redclaw grow-out occurs in earthen ponds, there is some interest in tank culture. PondsRedclaw aquaculture, both in juvenile and grow-out ponds, is performed in earthen ponds, typically 0.05 to 0.5 ha, with a depth of 1.0-2.5 m and a V-shape that allows rapid and complete drainage. Water is sourced from surface supplies or underground and should have a pH of 6.5-8.0, hardness of >40 ppm, and low levels of salinity (<5 ‰) and metals such as iron and manganese (<0.1 mg/litre). Artificial shelters are essential; they should be abundant, and their shape, specification and positioning should permit water to drain out freely and completely as the pond is drained. Stacks of pipes have been found to provide the most effective shelter for redclaw in the grow-out phase. Aeration is also essential and most frequently provided through airlift pumps, although other forms of aeration such as paddle-wheels and aspirators may be used. The aeration system should provide both oxygen input to the water and water circulation from bottom to top and around the pond. Fencing and netting over ponds is essential in areas where predatory birds and other species are prevalent. Grow-out ponds should be prepared with applications of lime, inorganic fertilisers and some organic material such as hay or manure. This initiates a plankton bloom, which provides additional, highly nutritious food and minimises light penetration. Grow-out necessitates an active stock management approach. Because redclaw breed so readily and profusely, the pond populations must be managed intensively. This includes stocking with known numbers of advanced juveniles of at least 5 g. Uniformity of size is very important. Maximum size at stocking should be 10 g. Stocking densities of 5-15/m2 are recommended. The food used will have an important bearing on production. Commercial crayfish pellets are available and have proven to be effective. A feeding frequency of once per day is adequate, preferably at dusk when crayfish are active. Active management of the pond environment is essential to maximise yields. There should be weekly monitoring of pH, dissolved oxygen and transparency (secchi disk) and monthly monitoring of hardness, alkalinity and ammonia. All measurements must be made at the water / soil interface on the bottom, and a contingency plan must be developed to counter poor water quality by applications of lime or fertiliser, or flushing of the pond with fresh water. Drying both juvenile and grow-out ponds between crops is essential to sterilise and re-vitalise the bottom. There is often a considerable build-up of organic waste after a culture period. The most effective management is to dry the pond for one to two weeks until cracks appear. Toxic compounds are broken down and useful nutrients are released. Crayfish may be manually sexed and stocked into separate ponds, particularly those that are to be grown out to >50 g. Avoiding, or at least minimising reproduction in grow-out ponds is important in effective management. Protection against birds, rats and eels, and any other potential predators must be provided. Complete enclosure netting and fencing is essential. Recent economic analysis indicated that the cost of netting (including materials and installation) is equivalent to 15 percent of the value of one crop. As losses to predators may be well in excess of this, netting is very cost-effective. The maximum grow-out period without grading should be six to nine months to minimise the possibility of un-managed reproduction. At each harvest, the stock must be size-graded and re-distributed as breeding stock, for marketing, for further grow-out or to be culled and discarded. The runts of each crop are unlikely to achieve market size in a reasonable time and it is best to remove them (and therefore their inferior genetics) from the farm population. The key factors for redclaw grow-out are: maximise growth and survival, and avoid reproduction. If these principles are applied, an average yield of more than 5 tonnes/ha/crop should be achieved. TanksDespite the focus of redclaw grow-out being earthen pond systems, there has been regular interest in the use of tank systems. These require only a modest investment in comparison with pond construction, and have therefore attracted great attention. Unfortunately, tank systems are not likely to provide profitable returns. Redclaw obtains the bulk of its food from decaying matter and associated microbes contained in the pond bottom mud. Although manufactured feeds have been developed for redclaw they do not appear to sustain acceptable growth rates in tank systems. Similarly, juvenile redclaw, which have slightly different feeding habits to the adults, cannot be cultured successfully in tanks because appropriate food cannot be provided. As a result, the juvenile redclaw become cannibalistic, leaving very few survivors. The level of production likely from redclaw culture in tanks would return considerably less than the operating costs, and certainly far less than the setup costs. Efforts to develop successful commercial tank systems for the cultivation of freshwater crayfish have a considerable history. Both in Australia and overseas, years of work have been applied to this approach, and yet the only commercially viable operations for redclaw are earthen pond based. There exists no confirmed or documented case of commercial success for crayfish production in a tank system.

ผลลัพธ์ (อังกฤษ) 2:

JUVENILE Production Production Juvenile and Grow-out to Market Size are managed separately, Although both are performed in Earthen Ponds. A managed juvenile production programme is essential to provide the advanced juveniles required for grow-out, and to make effective use of the superior broodstock selected. Depending on temperature and whether berried females or mature broodstock are used, a culture period of 3 to 4 months is necessary to achieve a mean size of juveniles of 5 to 15 g. The two most critical factors in juvenile production are the provision of shelter and food. The general Management of JUVENILE rearing Ponds is the Same as that described in this Fact Sheet under Ongrowing Techniques. Typically JUVENILE Ponds are stocked with mature females and males at a ratio of 4: 1 and a density of 1 500 / ha, carefully selected as. the best of the stock available from grow-out harvest. Well under managed conditions, 50-100 Advanced juveniles Will be produced per female broodstock, providing a yield of 60 000 to 120 000 juveniles / ha. At Water temperatures above 25 ºC, a Pond stocked with male and female JUVENILE Production is Ready for broodstock. harvest in four months. Alternatively, when berried females are stocked, the juvenile production pond is ready to harvest in three months. To maximise survival and growth of the juvenile redclaw, an abundance of shelter in the ponds is essential. This is usually provided in the form of bundles of synthetic mesh, tied onto a line with a weight at one end and a float at the other. Arranged in this manner, these bundles extend from the pond floor up into the water column providing many spaces and surfaces for the juveniles to utilise. These mesh bundles are stocked at one every 5 m2. Juvenile Production Ponds are carefully managed to provide an Abundance of planktonic organisms which utilize as the JUVENILE Crayfish Food. The planktonic organisms include both phytoplankton and zooplankton; it is primarily the latter that are consumed by the juvenile crayfish. As they Grow, they progressively Consume less plankton and more of the detrital Food that occurs on the surface of the Shelter Material and, more especially, on the Mud surface. Maintaining High levels of plankton Involves regular checking of Water quality and periodic fertilization of the. Water with nitrogen and phosphorus (diammonium phosphate typically at 50 kg / ha). Harvesting of the juveniles is achieved by a Number of methods. Sometimes individual mesh shelters are removed and the juveniles shaken out. However, the most effective method is to employ a flow trap. With this method, the pond is completely drained and all the crayfish are attracted into a trap. From there they Can be removed to Tanks and sorted, Counted and then stocked Into the Grow-out Ponds. Ongrowing Techniques Although all Commercial Redclaw Grow-out occurs in Earthen Ponds, there is Some interest in tank Culture. Ponds Redclaw Aquaculture, both in. juvenile and grow-out ponds, is performed in earthen ponds, typically 0.05 to 0.5 ha, with a depth of 1.0-2.5 m and a V-shape that allows rapid and complete drainage. Water is sourced from surface Supplies should have a pH of or Underground and 6.5-8.0, hardness of> 40 PPM, and low levels of salinity (<5 ‰) and Metals such as Iron and manganese (<0.1 mg / liter). Artificial. shelters are essential; they should be abundant, and their shape, specification and positioning should permit water to drain out freely and completely as the pond is drained. Stacks of pipes have been found to provide the most effective shelter for redclaw in the grow-out phase. Aeration is also essential and most frequently provided through airlift pumps, although other forms of aeration such as paddle-wheels and aspirators may be used. The aeration system should provide both oxygen input to the water and water circulation from bottom to top and around the pond. Fencing and netting over Ponds is Essential in areas where predatory Birds and Other species are prevalent. Grow-out Ponds should be prepared with Applications of Lime, inorganic fertilizers and Some Organic Material such as hay or Manure. This initiates a plankton bloom, which provides additional, highly nutritious food and minimises light penetration. Grow-out necessitates an active stock management approach. Because redclaw breed so readily and profusely, the pond populations must be managed intensively. This includes stocking with known numbers of advanced juveniles of at least 5 g. Uniformity of size is very important. Maximum size at stocking should be 10 g. Stocking densities of 5-15 / m2 are Recommended. The Food Will have an important Bearing used on Production. Commercial crayfish pellets are available and have proven to be effective. A feeding frequency of once per Day is adequate, preferably at Dusk when Crayfish are active. Active Management of the Environment Pond is Essential to maximize yields. There should be weekly monitoring of pH, dissolved oxygen and transparency (secchi disk) and monthly monitoring of hardness, alkalinity and ammonia. All measurements must be Made at the Water / soil interface on the bottom, and a contingency Plan must be developed to counter poor Water quality by Applications of Lime or Fertiliser, or FLUSHING of the Pond with Fresh Water. Drying both JUVENILE and Grow-out. ponds between crops is essential to sterilise and re-vitalise the bottom. There is often a considerable build-up of organic waste after a culture period. The most effective management is to dry the pond for one to two weeks until cracks appear. Toxic compounds are useful Broken down and nutrients are Released. Crayfish May be manually Sexed and Separate Into Ponds stocked, particularly those that are to be Grown out to> 50 G. Avoiding, or at Least Minimising Reproduction in Grow-out Ponds is important in effective Management. Protection against Birds, rats and eels, and any Other potential predators must be provided. Complete enclosure netting and fencing is essential. Recent economic analysis indicated that the cost of netting (including materials and installation) is equivalent to 15 percent of the value of one crop. May losses to predators as well be in excess of this, is very cost-effective netting. The maximum Grow-out period should be Six to Nine Without grading months to Minimise the possibility of un-managed Reproduction. At each harvest, the stock must be size-graded and re-distributed as breeding stock, for marketing, for further grow-out or to be culled and discarded. The runts of each crop are unlikely to achieve market size in a reasonable time and it is best to remove them (and therefore their inferior genetics) from the farm population. The key factors for redclaw grow-out are: maximise growth and survival, and avoid reproduction. If these principles are Applied, an average yield of more than 5 tonnes / ha / Crop should be achieved. Tanks Despite the Focus of Redclaw Grow-out Systems being Earthen Pond, there has been interest in the use of regular tank Systems. These require only a modest investment in comparison with pond construction, and have therefore attracted great attention. Unfortunately, tank systems are not likely to provide profitable returns. Redclaw obtains the bulk of its food from decaying matter and associated microbes contained in the pond bottom mud. Although Manufactured feeds have been developed for Redclaw they do not appear to Sustain acceptable growth Rates in tank Systems. Similarly, JUVENILE Redclaw, which have Slightly different feeding habits to the adults, Can not be cultured successfully in Tanks because appropriate Food Can not be provided. As a Result, the JUVENILE Redclaw Become Cannibalistic, Leaving very few survivors. The level of Production likely from Redclaw Culture in Tanks would Return considerably less than the operating costs, and certainly Far less than the Setup costs. Efforts to develop successful Commercial tank Systems. for the cultivation of freshwater crayfish have a considerable history. Both in Australia and overseas, years of work have been applied to this approach, and yet the only commercially viable operations for redclaw are earthen pond based. There exists no confirmed or documented case of commercial success for crayfish production in a tank system.

ผลลัพธ์ (อังกฤษ) 3:

Juvenile production

Juvenile production and grow-out to market size are, managed separately although both are performed. In earthen ponds. A managed juvenile production programme is essential to provide the advanced juveniles required, for grow-out. And to make effective use of the superior broodstock selected. Depending on temperature and whether berried females or mature. Broodstock, are usedA culture period of 3 to 4 months is necessary to achieve a mean size of juveniles of 5 to 15 g. The two most critical. Factors in juvenile production are the provision of shelter and food. The general management of juvenile rearing ponds is. The same as that described in this fact sheet under ongrowing techniques.

.Typically juvenile ponds are stocked with mature females and males at a ratio of 4: 1 and a density of 1 500 / ha carefully,, Selected as the best of the stock available from grow-out harvest. Under well managed conditions 50-100 advanced, juveniles. Will be produced per, broodstock female providing a yield of 60 000 to 120 000 juveniles / ha.

At water temperatures above 25, º CA juvenile production pond stocked with male and female broodstock is ready for harvest in four months, Alternatively,. When berried females are stocked the juvenile, production pond is ready to harvest in three months. To maximise survival. And growth of the, juvenile redclaw an abundance of shelter in the ponds is essential. This is usually provided in the form. Of bundles of, synthetic meshTied onto a line with a weight at one end and a float at the other. Arranged in this manner the these bundles extend from EOS The pond floor up into the water column providing many spaces and surfaces for the juveniles to utilise in can These mesh bundles EOS Are stocked at one every 5 m2.

.Juvenile production ponds are carefully managed to provide an abundance of planktonic organisms which the juvenile crayfish. Utilise as food. The planktonic organisms include both phytoplankton and zooplankton; it is primarily the latter that are. Consumed by the juvenile crayfish As, they grow.They progressively consume less plankton and more of the detrital food that occurs on the surface of the shelter material. ,, and more especially on the mud surface.

Maintaining high levels of plankton involves regular checking of water quality. And periodic fertilisation of the water with nitrogen and phosphorus (typically diammonium phosphate at 50 kg / HA).

.Harvesting of the juveniles is achieved by a number of methods. Sometimes individual mesh shelters are removed and the. Juveniles shaken out. However the most, effective method is to employ a flow trap. With, this method the pond is completely. Drained and all the crayfish are attracted into a trap. From there they can be removed to tanks, and sortedCounted and then stocked into the grow-out ponds.

Ongrowing techniques Although all commercial redclaw grow-out occurs. In earthen ponds there is, some interest in tank culture.



Redclaw, Ponds aquaculture both in juvenile and, grow-out ponds. Is performed in earthen ponds the typically 0.05 to 0.5 ha the with a depth of 1.0-2.5 m and a V-shape that allows rapid and complete EOS Drainage in canWater is sourced from surface supplies or underground and should have a pH, of 6.5-8.0 hardness of > 40 ppm and low, levels. Of salinity (< 5 we obsessively covered the 2012) and metals such as iron and manganese (< 0.1 mg / litre).

Artificial shelters are essential; they should. Be abundant and shape, their, and specification positioning should permit water to drain out freely and completely as the. Pond is drained.Stacks of pipes have been found to provide the most effective shelter for redclaw in the grow-out phase. Aeration is also. Essential and most frequently provided through airlift pumps although other, forms of aeration such as paddle-wheels and. Aspirators may be used. The aeration system should provide both oxygen input to the water and water circulation from bottom. To top and around the pond.Fencing and netting over ponds is essential in areas where predatory birds and other species are prevalent.

Grow-out. Ponds should be prepared with applications, of lime inorganic fertilisers and some organic material such as hay or, manure. This initiates a, plankton bloom which provides additional highly nutritious, food and minimises light penetration.Grow-out necessitates an active stock management approach. Because redclaw breed so readily and profusely the pond, populations. Must be managed intensively. This includes stocking with known numbers of advanced juveniles of at least 5 g. Uniformity. Of size is very important. Maximum size at stocking should be 10 g. Stocking densities of 5-15 / m2 are recommended.

.The food used will have an important bearing on production. Commercial crayfish pellets are available and have proven to. Be effective. A feeding frequency of once per day is adequate preferably at, dusk when crayfish are active.

Active management. Of the pond environment is essential to maximise yields. There should be weekly monitoring, of pHDissolved oxygen and transparency (Secchi disk) and monthly monitoring of hardness, alkalinity and ammonia in can All measurements EOS Must be made at the water which soil interface on the bottom the and a contingency plan must be developed to counter poor water EOS Quality by applications of lime or fertiliser or flushing, of the pond with fresh water.

.Drying both juvenile and grow-out ponds between crops is essential to sterilise and re-vitalise the bottom. There is often. A considerable build-up of organic waste after a culture period. The most effective management is to dry the pond for one. To two weeks until cracks appear in can Toxic compounds are broken down and useful nutrients are released in can

EOSCrayfish may be manually sexed and stocked into separate ponds particularly those, that are to be grown out to > 50 g, Avoiding,. Or at least minimising reproduction in grow-out ponds is important in effective management.

Protection, against birds. Rats, and eels and any other potential predators must be provided. Complete enclosure netting and fencing is essential.Recent economic analysis indicated that the cost of netting (including materials and installation) is equivalent to 15 percent. Of the value of one crop. As losses to predators may be well in excess of this netting is, very cost-effective.

The maximum. Grow-out period without grading should be six to nine months to minimise the possibility of un-managed reproduction. At. Each, harvestThe stock must be size-graded and re-distributed as breeding, marketing stock for, further for grow-out or to be culled. And discarded. The runts of each crop are unlikely to achieve market size in a reasonable time and it is best to remove. Them (and therefore their inferior Genetics) from the farm population. The key factors for redclaw grow-out are: maximise. Growth, and survivalAnd avoid reproduction. If these principles, are applied an average yield of more than 5 tonnes / HA / crop should be, achieved.



Despite Tanks the focus of redclaw grow-out being earthen, pond systems there has been regular interest in the use of. Tank systems. These require only a modest investment in comparison with pond construction and have, therefore attracted. Great, Unfortunately attention.Tank systems are not likely to provide profitable returns. Redclaw obtains the bulk of its food from decaying matter and. Associated microbes contained in the pond bottom mud. Although manufactured feeds have been developed for redclaw they do. Not appear to sustain acceptable growth rates in tank systems.

, redclaw Similarly juvenile, have which slightly different. Feeding habits to, the adultsCannot be cultured successfully in tanks because appropriate food cannot be provided. As a result the juvenile, redclaw. Become cannibalistic leaving very, few survivors.

The level of production likely from redclaw culture in tanks would return. Considerably less than the operating costs and certainly, far less than the setup costs.

.Efforts to develop successful commercial tank systems for the cultivation of freshwater crayfish have a considerable, history. Both in Australia, and overseas years of work have been applied to this approach and yet, the only commercially viable operations. For redclaw are earthen pond based.There exists no confirmed or documented case of commercial success for crayfish production in a tank system.