In just a couple of decades, aquaculture has been transformed from a niche academic interest to the linchpin of national economies. Commonly referred to as fish-farming, the practice of aquaculture involves the breeding, growing and harvesting of any and all forms of marine organisms, from fish and shellfish to plants and algae. The bulk of this produce goes into the booming seafood industry, but there are many further applications for aquaculture-farmed produce, from pharmaceuticals and cosmetics to biofuel manufacture. Read on to find out more.
Aquaculture is essentially the marine counterpart of the familiar land-based agriculture. Aquaculture can be carried out in natural bodies of water, such as ponds, marshes and the open sea, or in special man-made structures, including tanks and hatcheries. When man-made closed tanks are used, a recirculation system must be utilised to replenish the water with oxygen and keep the aquaculture system clean.
There is a wide range of goods produced via the use of aquaculture. Besides providing fish of all kinds to satisfy the appetites of consumers across the world, aquaculture is also employed to produce bait fish, ornamental fish and crustaceans, molluscs and caviar to cater for the increasingly sophisticated tastes of modern consumers. Sea vegetables, edible seaweed and algae are also grown.
A huge number of different applications and end uses for these products also exist. The stocks of wild populations suffering from overfishing, perhaps most notoriously the cod of the North Sea, can be rebuilt by growing specimens to early maturity and releasing them into the wild. Such a strategy of stock restoration and enhancement can also be used to assist the recovery of coastal habitats such as oyster reefs.
Algae and other marine plants are used as inputs in a growing number of industries. Applications range from pharmaceuticals, medicine, cosmetics to human nutritional products, animal feed and associated agrochemicals. Given that algae grow relatively quickly, offer high biofuel yields, do not compete for space and resources with agriculture and even consume CO2, algae represent a particularly promising tool for use in the lubricants, plastics, fuel and environmental remediation industries.
Types of Aquaculture
Aquaculture can be divided into two main types. Freshwater aquaculture focuses on species native to freshwater bodies such as rivers, streams and lakes. Whilst this form of aquaculture can be carried out in any body of freshwater, the need to control certain conditions means that man-made land-based tanks with water-recirculating systems are predominantly used.
Marine aquaculture, by contrast, refers to the farming of species in the saltwater of the seas and oceans. Man-made ponds and tanks are occasionally used for marine aquaculture, but the majority of applications take place in the open sea using cages and containers submerged and secured at the required depth.
Species of animals farmed include common fish such as salmon, trout and bass and overfished specimens like cod and haddock. Smaller enterprises focus on less popular examples, including tilapia, seabream, seabass and catfish. Aquacultural producers in the United States rely on other varieties of marine life with a stronger focus on production for food consumption. Varieties typically include mussels, clams, shrimp and oysters.
Certain species, such as salmon and sea trout, are anadramous fish, meaning that they can survive in both the sea and freshwater. Salmon are born in freshwater rivers but spend most of their lives out at sea, returning to their native river to swim upstream and spawn at the end of their lives. This is replicated for farmed salmon: they are hatched and reared in freshwater facilities, either tanks or cages, before being moved to seawater fish farms after their first year.