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
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.
