Extensive culture: low intensity aquaculture providing only small
increases over natural productivity. Extensive fish culture systems
have low stocking densities, don’t use rearing units specifically
engineered for aquaculture, and don’t involve artificial diets
Intensive culture: fish culture methods yielding far in excess of
natural productivity levels. Intensive systems utilize high stocking
rates, man-made rearing units and artificial diets.
1.) Pond culture: system based on earthen ponds, where some or
all of the food consumed is from natural production and there is
minimal water flow.
2.) Raceway Culture: system based on circular or straight
raceways (tanks) with high water flow and minimal water reuse.
3.) Cage Culture: system in which fish are confined to net pens
or cages placed in ponds, rivers, lakes, or ocean.
4.) Tank Culture Utilizing Water Recirculation: tank culture
system where nearly 100% of the water is reused and cleansed
by sophisticated filtration systems.
1.) Minimum demand on limited water resources. The limited
quantity of high quality water in aquifers and on the surface is an
indication that water recirculation systems will become
increasingly important as a means of meeting the demand for fish.
2.) Minimum environmental impact. Recirculation systems permit
the concentration and removal of fish wastes so that water pollution
can be controlled and minimized.
3.) Few government permits are required. Because of limited
impact on environment, and limited withdrawal of waste water, few
permits are required for aquaculture systems based on water
recirculation.
4.) Closed circulation systems can be located near markets.
Suitable sites for other systems are dependent on location of
suitable water or land resources. Recirculation systems can be
located so that transportation costs and time between harvest can
be minimized.
5.) Water quality and temperature can be maximized. Water
temperature can be maintained at the optimum level for fast
growth and optimum feed conversion.
6.) Minimize losses from environmental hazards such as predators,
pollutants, and disease. Fish produced in closed recirculation
systems are safe from environmental pollutants and many
pathogens.
7.) Minimum space requirements for level of production. In
comparison to other types of systems, protein production in closed
systems require very little space.
1.) High Capital Costs. Capital costs of buildings, pumps,
tanks, heaters, etc. are higher than other systems of
aquaculture.
2.) High Operating Costs. Closed systems require pumping
water though tanks and filters. The operating costs of pumps
are significant, and these costs may be the difference between
profitable and nonprofitable fish farms.
3.) Vulnerability to Mechanical Failure. Pumps make fish farm
vulnerable to breakdowns and blackouts which can result in
catastrophic losses of fish.
4.) Difficulties with Fish Health Management. Disease
outbreaks, once they occur, are difficult to manage. Pathogens in
the system find refuge in the biological filter and are difficult to
remove. Often the only option is to treat the fish in the tank, thus
killing the bacteria in the biofilter.
5.) Higher level of management is required. Unless managed
properly, sub-optimal conditions can occur that will result in
disease outbreaks and increased mortality. A much higher level
of system monitoring is required than in most other systems.
Facilities Needed for Indoor Recirculation Systems
1.) Electricity: ground fault protection should be provided because
of the equipment in and around water
2.) Electrical circuits: should have at least 2 separate circuits to
allow for the water pump and (if needed) heaters.
3.) Floor drain: in case of water spill or overflow, a drain is
needed (especially for emergency situations)
4.) Rearing unit: filters and rearing unit require about 7 ½ feet x 5
½ feet of floor space.
5.) Storage space: needed for equipment and feed storage
6.) Auxiliary tank space: additional tank space
7.) Operating room: enough space (min. of 3 ft.) around the
system to allow for ample room to feed, harvest, clean,etc.
**Additional items to consider: lab space & weight of system
ASSIGNMENT TO BE COMPLETED BY END OF CLASS:
1.) What are four basic types of intensive fish culture systems?
2.) What are the advantages of utilizing a water recirculation
system for raising fish?
3.) What are disadvantages of a water recirculation system for
raising fish?
4.) Define the following terms: net pen, water quality, capital,
extensive culture, intensive culture