1.2 Methods of Production

Aquaculture production methods are described on a scale from extensive to intensive management. The extensive operations are outdoor ponds with little human intervention or supporting activity in contrast to intensive, which rely on more human intervention. The reader might visualize extensive operation as the farm pond for watering cattle that is stocked with some fish for recreational fishing. The fish feed on natural feeds and survive in the environment determined by weather changes. As more human intervention such as feeding and predator protection is provided, the system will move closer to the intensive side of the management spectrum.

At the intensive side of the scale, the reader can visualize the recirculating aquaculture systems (RASs)—indoor systems for rearing fish year-round with automatic feeders and high levels of biosecurity. Intensive management systems provide husbandry practices and thus more shelter, feeding, a controlled environment, controlled spawning, water quality control, and other life-supporting functions under a variety of culture conditions. This greatly reduces the water source requirement, the volume of effluent discharged. These systems are described in more detail in Chapter 2. The RASs have been used for finfish and shellfish and may be incorporated into aquaponic systems to include seaweed or terrestrial horticulture.

Integration

Another method of aquaculture production is called integration. Integration systems combine two or more units of production. The units can be plant and animal combinations such as aquaponic systems that utilize fish waste to fertilize the plants, increasing growth. Conversely, the plant growth removes nutrient matter from the water that could become toxic to the fish. Carp are often frequently used as a multispecies culture since they are filter feeders. Pictured below is an example of an integrated system in which pigs stand above grates, and when they defecate, the feces fall into the water where there are carp. Carp are opportunistic and will eat the feces and the increased algal growth from the enriched water. Furthermore, you could take this system to the next level by making it a multilevel integration system.

Multilevel Integration

Multilevel integration systems combine vertebrate and invertebrate cultures. The fish feed and leave feed particles and feces for shrimp or other bottom scavengers such as filter feeders (e.g., mussels and clams). Algae or kelp is employed in some systems. An integrated system can have fresh, brackish, or marine water and can involve outdoor ponds or net pens. These systems’ aquatic species more fully utilize the nutrients or by-products of the system to improve efficiency and sustainability.