Emergency power for fish produced in intensive, pond-based systems

Authors: Brown, Travis

Submitted to: The Catfish Journal
Publication Type: Trade Journal
Publication Acceptance Date: 5/12/2016
Publication Date: 6/1/2016
Citation: Brown, T.W. 2016. Emergency power for fish produced in intensive, pond-based systems. The Catfish Journal. 30:(3)16-17.

Interpretive Summary: Power failure in a heavily stocked and fed pond-based culture system can result in massive fish losses within minutes. Even in a conventional pond with a stand-by tractor powered aerator, the shock of a sudden loss of power can dramatically affect production resulting in mortalities and reduced performance from stress related low dissolved oxygen conditions. This is especially true in split-ponds and other intensive pond-based systems if fish are close to or at market size when total biomass is greatest. In some cases, there may be too many fish in the culture area (basin) for the night man to have adequate time to put in and utilize a tractor-powered aerator in emergency situations. This is a result of a reduced response time due to a greater fish-to-water volume ratio compared to conventional ponds. All this means is that sufficiently sized and dependable emergency electric power systems are essential for intensive, pond-based aquaculture. A good generator set with adequate controls for a 10-acre split-pond may run as high as $21,000 to $37,000 ($2,100 to $3,700 per acre) including installation. However, this is a minor percentage of the total farm investment when the total cost is distributed over time, and should be viewed as insurance or just part of the cost of doing business. Cost could be reduced by purchasing used generators which some farmers have done. In addition, a reduction of 50% in costs can be expected if the producer chooses to only operate half of the aerators with generator power. Another way to reduce costs is to install a larger generator set to operate many ponds because generator price per kW decreases as they increase in size (power). However this would need to be studied in detail because more and larger diameter wire (and conduit) for longer runs, and larger, more expensive electronics (transfer switches, etc.) will be needed. Additional costs can be expected from maintenance, repairs, and routine operation. Useful life values for generator sets under different operational conditions can be obtained from each manufacturer to determine depreciation if needed. There is too much risk associated with using intensive, pond-based culture systems without standby power. If you take the gamble to not incorporate back-up power into your system, then you can expect, sooner or later, to get hit with catastrophic fish losses which is what we dread the most. A good generator set with adequate controls for a 10-acre split-pond may run as high as $21,000 to $37,000 ($2,100 to $3,700 per acre) including installation. However, this is a minor percentage of the total farm investment when the total cost is distributed over time, and should be viewed as insurance or just part of the cost of doing business. Cost could be reduced by purchasing used generators which some farmers have done. In addition, a reduction of 50% in costs can be expected if the producer chooses to only operate half of the aerators with generator power. Another way to reduce costs is to install a larger generator set to operate many ponds because generator price per kW decreases as they increase in size (power). However this would need to be studied in detail because more and larger diameter wire (and conduit) for longer runs, and larger, more expensive electronics (transfer switches, etc.) will be needed. Additional costs can be expected from maintenance, repairs, and routine operation. Useful life values for generator sets under different operational conditions can be obtained from each manufacturer to determine depreciation if needed. There is too much risk associated with using intensive, pond-based culture systems without standby power. If you take the gamble to not incorporate back-up power into your system, then you can expect, sooner or later, to get hit with catastrophic fish losses which is what we dread the most.

Technical Abstract: Power failure in a heavily stocked and fed pond-based culture system can result in massive fish losses within minutes. Even in a conventional pond with a stand-by tractor powered aerator, the shock of a sudden loss of power can dramatically affect production resulting in mortalities and reduced performance from stress related low dissolved oxygen conditions. This is especially true in split-ponds and other intensive pond-based systems if fish are close to or at market size when total biomass is greatest. In some cases, there may be too many fish in the culture area (basin) for the night man to have adequate time to put in and utilize a tractor-powered aerator in emergency situations. This is a result of a reduced response time due to a greater fish-to-water volume ratio compared to conventional ponds. All this means is that sufficiently sized and dependable emergency electric power systems are essential for intensive, pond-based aquaculture. Unfortunately, fish losses in intensive pond-based systems have been documented on several catfish farms recently. As a result, many farmers in Mississippi, Arkansas, and Alabama have implemented emergency electric power systems on their farms in an effort to reduce the possibility of massive fish kills. Power failure on catfish farms in the south is quite common and it seems like the highest probability of losing power is in the middle of summer when farmers have the least amount of time to respond with emergency aeration. Power failure can happen for various reasons. Some of the most common examples are: blown standard fuses, blown transformer fuses, electric motor failure and/or starter failure, power line disintegration, lightning, and transformer failure to name few. Some of these problems can be prevented by proper maintenance, repairs, and grounding, while others cannot, due to useful life of equipment, animals, and Mother Nature. This article outlines the main factors a producer needs to know when selecting a standby power setup by using a 10-acre split-pond as an example including initial investment costs.