Fish-Culture

The artificial reproduction, rearing and transplantation of fish is called pisciculture. It is also called fish farming. The term pisciculture is specific to aqua farming or the raising of fish inside of tanks or in house ponds. Pisciculture is a form of aquaculture as aquaculture is the scientific rearing and management of all aquatic animals. A facility that releases juvenile fish into the wild for recreational fishing or to supplement a species’ natural numbers is generally referred to as a fish hatchery. Global demand is increasing for dietary fish protein, which has resulted in widespread overfishing in wild fisheries, resulting in significant decrease in fish stocks and even complete depletion in some regions. Fish farming allows establishment of artificial fish colonies that are provided with sufficient feeding, protection from natural predators and competitive threats, access to veterinarian service, and easier harvesting when needed, while being separate from and thus do not usually impact the sustainable yields of wild fish populations.

Aquaculture vs Pisciculture

Intensive Aquaculture

An intensive fish farming system is the well-managed form of fish farming, in which all attempts are made to achieve maximum production of fish from a minimum quantity of water.

  • This system involves small ponds/tanks/raceways with very high stocking density (10-50 fish/m3 of water).
  • Although intensive aquaculture is completely mechanized and self-contained it can have a detrimental impact on the environment.
  • The biggest problem caused by intensive aquaculture is the difficulty in properly dealing with the nutrient rich effluent.
  • Effluent contains high levels of both organic and inorganic nutrients like ammonia, phosphorus, dissolved organic carbon, dissolved organic nitrogen and dissolved organic phosphorus.
  • If not disposed of correctly the effluent could cause a number of problems including eutrophication, and hypernutrification
  • Ingenious solutions have been developed to reduce the negative effects to the environmental caused by this effluent. The most effective solution is the advent of aquaponics.
Aquaculture fish farming of salmon and mackerel in the Chilean fjords about 6 km south from Castro, on March 16, 2019. Fish pens and crew scow can be moved.

Aquaponics is the combination of Intensive aquaculture (fish farming) and hydroponics (growing plants without soil). Aquaponic systems use the nutrient rich effluent from fish tanks as fertilizers for produce. The advent of aquaponics has made the aquaculture industry into a sustainable and Eco-friendly business.

Extensive Aquaculture

Extensive aquaculture is the other form of fish farming. It is more basic than intensive aquaculture in that less effort is put into the husbandry of the fish.

  • Extensive aquaculture is done in the ocean, natural and man-made lakes, bays, rivers, and Fiords.
  • Fish are contained within these habitats by multiple mesh enclosures which also function as trapping nets during harvest.
  • Since fish are susceptible to the elements, site placement is essential to ensuring rapid growth of the targeted species.
  • The drawback of these facilities is that they depend on the surrounding area for good water quality in order to reduce mortality and increase the survivorship and growth rate of the fish.
  • Fish chosen for extensive aquaculture are very hardy and often do well in high densities.Seaweed, prawns, muscles, carp, talapia, tuna and salmon are the most prominent forms of extensive aquacultured seafood .

Extensive Aquaculture – Drawbacks

Extensive aquaculture facilities have negative impacts on the environment as well. Natural habitats are destroyed in the development of man made ponds used for extensive aquaculture. In the Philippines, shrimp aquaculture is responsible for the destruction of thousands of acres of mangrove fields which serve as nurseries and living habitats for many marine organisms. Benthic habitats are being depleted due to the high amount of organic waste produced by the fish which settles below their pens. Phytoplankton and algae breakdown fecal matter and residual fish meal reducing the amount of available oxygen in the water column,which chokes and kills the Benthic organisms. Another serious problem acquainted with extensive aquaculture is the introduction of invasive species into ecosystems. Escaped fish increase the competition between organisms for limited resources. Also, when foreign fish interbreed with wild species, they upset the genetic variability of the species, making them more prone to disease and infection. The high density of fish in these mesh tanks is very tempting for predators of the sea and air. To protect the harvest from predators protective netting is set up at a high cost. Often times predatorial fish and mammals like seals, sharks, and tuna get caught in these barrier nets and die. Some farmers protect their stocks from predatorial birds such as pelicans and albatross by shooting these sometimes endangered creatures.

Pisciculture Complex, outside Rio Branco, Brazil

Today, only industrialized nations have the funds to invest in intensive aquaculture. Mass produced aquacultured fish has lowered the wholesale price of fish, thus drawing customers away from the already poor fishermen. Today, the only form of aquaculture available to small time fishermen is in the form of grow out pens for juvenile fish. Research is being done to create more complex and affordable forms of extensive aquaculture for subsistence fishermen in order to increase their standard of living, and more importantly, act as an incentive to protect endangered species.

World capture fisheries and aquaculture production by production mode, from FAO’s Statistical Yearbook 2020