Fisheries

Fisheries

Fisheries can be divided into two term where it is done through capture of wild fish or culturing fishes by aquafarming. In this topic we are going to discuss about fisheries in aquafarming, fishes is reared and harvested when matured to be commercialise to market. The increase of food demand worldwide had cause overfishing in the ocean which will eventually cause the extinction of fish species so the idea of culturing fishes is done to sustain life and fulfil the requirement of food in the world. With fishery aquafarming, many types of fish can be cultured and marketed for their high value and low cost to sustain the culture process.

Aquaculture

Aquaculture is the farming of aquatic plant and animal which involves cultivating freshwater and saltwater populations under controlled conditions, and can be contrasted with commercial fishing, which is the harvesting of wild fish. Mariculture is also included in aquaculture it refers to aquaculture practice in marine environments and in underwater habitat. It is necessary to improve nutrition and food security and to supply growing global demand for seafood, which can’t be met by wild fisheries. There many ways aquatic species can be cultured and below are some of the methods used in culturing different types of fishes.

Open-net pen systems

The system is cultured in the natural habitat of the fishes and is usually used offshore in coastal areas or in freshwater lakes, open-net pens or ‘cages’ are considered a high-risk aquaculture method as they allow for free and unregulated exchange between the farm and the surrounding environment. Farmed salmon are one of the example that can be farmed in this manner. Open net pens system have low cost in sustaining the farm needs as it does not require any management in the water system. Disadvantages of this system is that there is a free exchange of high concentrations of waste, chemicals, parasites and disease that could cause. Possibility is high for the farmed fish to escape and they also attract predators, such as marine mammals, that can get tangled and drown in fish farm nets. It is not a recommended aquaculture method to sustain life as it disturb the aquatic life found in the cultured area and also brings danger to the cultured fish.

Closed Systems

Closed systems or ‘closed containment’ is the improved aquaculture method of open-net system where the farming methods use a barrier to control the exchange between farms and the natural environment. This significantly reduces pollution, fish escapes, negative wildlife interactions, and parasite and disease transfer from farms to marine and freshwater ecosystems.

Raceways

Flowing water is diverted from natural streams or a well. Raceways are typically used for raising rainbow trout. To be considered a low-risk method, waste must be treated and fish escapes prevented.

Recirculation systems

 Known as RAS, the water in these systems is treated and re-circulated to be reused. Most used method in aquaculture and almost any type of finfish can be raised in recirculating systems. Common species farmed in this manner include Arctic char, striped bass, barramundi, sturgeon, and increasingly salmon. This system does not mix with natural water sources, which is able to prevent problems and risk such as mitigates pollution, parasite transfer, fishes escape or being targeted by predator. This is the most efficient method as compared to other aquaculture method with optimum yield and low cost however the starting of the cost is quite expensive but maintenance cost is reliably cheap. 

Suspended-aquaculture

Farmers grow shellfish on beaches or suspend them in water by ropes, plastic trays or mesh bags. The shellfish farmed using these methods are filter feeders and require only clean water to thrive. Oysters, mussels and clams are cultured using suspension systems. Shellfish farming using this method is often ‘low risk’ if the farmed species is native to the area and if the farm has sufficient flow to prevent waste accumulation.

Aquatic plants

Cultivating emergent aquatic

plants in floating containers.

Algaculture the culture of microalgae referred to as phytoplankton, microphytes, or planktonic algae constitute the majority of cultivated algae. Seaweed farming is known as macroalgae have many commercial and industrial uses, but due to their size and specific requirements, they are not easily cultivated on a large scale and are most often taken in the wild. Culturing of aquatic plant require a lot of consideration into the environment suitability for the plant. Growing algae needs water, carbon dioxide, minerals and light are the main important factor and other factor such as temperature, light and mixing, odor and oxygen, and nutrients.

Fish

The farming of fish is the most common form of aquaculture. It involves raising fish commercially in tanks, ponds, or ocean enclosures, usually for food. 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. Worldwide, the most important fish species used in fish farming are, in order, carp, salmon, tilapia and catfish.

In the Mediterranean, young bluefin tuna are netted at sea and towed slowly towards the shore. They are then interned in offshore pens where they are further grown for the market. In 2009, researchers in Australia managed for the first time to coax tuna (Southern bluefin) to breed in landlocked tanks.

A similar process is used in the salmon farming section of this industry; juveniles are taken from hatcheries and a variety of methods are used to aid them in their maturation. For example, as stated above, one of the most important fish species in the industry, the salmon, can be grown using a cage system. This is done by having netted cages, preferably in open water that has a strong flow, and feeding the salmon a special food mixture that will aid in their growth. This process allows for year-round growth of the fish, and thus a higher harvest during the correct seasons.

Crustaceans

Crustacean are aquatic animal with shells like crabs, crayfish, prawn, and shrimp. Shrimp farming has been group into 2 category, marine shrimp farming and freshwater prawn farming. Shrimp farming has changed from its traditional, small-scale form in Southeast Asia into a global industry. Technological advances have led to ever higher densities with broodstock is shipped worldwide. Virtually all farmed shrimp are penaeids from the family Penaeidae, and just two species of shrimp, the Pacific white shrimp and the giant tiger prawn, account for about 80% of all farmed shrimp.

Freshwater prawn farming shares many characteristics with, including many problems with, marine shrimp farming. Unique problems are introduced by the developmental life cycle of the main species, the giant river prawn.

Molluscs

Abalone farm

Aquaculture shellfish include various oyster, mussel and clam species. These bivalves are filter and/or deposit feeders, which rely on ambient primary production rather than inputs of fish or other feed. As such shellfish aquaculture is generally perceived as benign or even beneficial. Depending on the species and local conditions, bivalve molluscs are either grown on the beach, on longlines, or suspended from rafts and harvested by hand or by dredging. Over-fishing and poaching have reduced wild populations to the extent that farmed abalone now supplies most abalone meat.