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Fish farming is the principal form of aquaculture,while other methods may fall under mariculture. Fishfarming involves raising fish commercially in tanks orenclosures, usually for food. A facility that releasesyoung (juvenile) fish into the wild for recreationalfishing or to supplement a species natural numbers isgenerally referred to as a fish hatchery. The mostcommon fish species raised by fish farms aresalmon, carp, tilapia, Europeanseabass, catfish and cod.There is an increasing demand for fish andfish protein, which has resulted inwidespread overfishing in wild fisheries. Fishfarming offers fish marketers another source. 2
2.M A J O R C A T E G O R I E S O F F I S H A Q # E X T E NS I V E A QUA CUL T URE # I NT E NS I V E A QUA CUL T URE EXTENSIVE AQUACULTURELimiting for growth here is the available food supply bynatural sources,commonly z o o p l a n k t o n f e e d i n go n p e l a g i c a l g a e or b e n t h i c animals,s u c ha s c r u s t a c e a n s and m o l l u s k s . T i la p i a species filter feed directlyon p h y t o p l a n k t o n , which makes higherproduction possible. The photosynthetic production can beincreased by f e r t i l i z i n g the p o n dwa t e r wi t h a r t i f i c i a lf e r t i l i z e r mi x t u r e s , s u c ha s p o t a s h ,p h o s p h o r u s ,n i t r o g e n and micro-elements. Because most fishare c a r n i v o r o u s , they occupy a higher place inthe t r o p h i c c h a i n and t h e r e f o r eo n l y a t i n y f r a c t i o n o fp r i ma r y p h o t o s y n t h e t i cp r o d u c t i o n (t y p i c a l l y 1%) w i l lb e c o n v e r t e d i n t o h a r v e s t -a b l e f i s h .Another issue is the risk of a l g a l b l o o m s .Wh e n t e m p e r a t u r e s , n u t r i e n t 5s u p p l y a n d a v a i l a b l e s u n l i g h ta r e o p t i ma l f o r a l g a l g r o w t h ,
INTENSIVE AQUACULTUREIn these kinds of systems fish production per unitof surface can be increased at will, as long assufficient o x y g e n , fresh water and food areprovided. Because of the requirement of sufficientfresh water, a massive w a t e rp u r i f i c a t i o n system m u s t b ei n t e g r a t e d i n t h e f i s hf a r m. A c l e v e r w a y t oa c h i e v e t h i s i s t h ec o mb i n a t i o nh y d r o p o n i c h o r t i c u l t u r e and w a t e r t r e a t m e n t . The cost ofinputs per unit of fish weight is higher than inextensive farming, especially because of the highcost of f i s h f e e d . Expressing eggs from a female rainbow trout 6Essential here is a e r a t i o n of t h ewa t e r , a s f i s h n e e d a
Specific types of fish farmsCage systemFish cages are placed in lakes, ponds, rivers oroceans to contain and protect fish until theycan be harvested. The method is also called"off-shore cultivation" when the cages areplaced in the sea. They can be constructed of awide variety of components. Fish are stocked incages, artificially fed, and harvested when theyreach market size. 7
Irrigation ditch or pond systemsThese use irrigation ditches or farm ponds to raisefish. The basic requirement is to have a ditch orpond that retains water, possibly with an above-ground irrigation system. Using this method, onecan store ones water allotment in ponds orditches, usually lined with bentonite clay. In smallsystems the fish are often fed commercial fish food,and their waste products can help fertilize thefields. In larger ponds, the pond grows water plantsand algae as fish food. Control of water quality is crucial. Fertilizing,clarifying and pH control of the water can increaseyields substantially.Yields can be low if the fish grow ill from electrolytestress. 8
Composite fish cultureThe Composite fish culture system is a technologydeveloped in India by the Indian Council of AgriculturalResearch in the 1970s. In this system both local andimported fish species, a combination of five or six fishspecies is used in a single fish pond. These species areselected so that they do not compete for food amongthem having different types of food habitats. Fish used in this system include catla and silvercarp which are surface feeders, rohu a column feederand mrigal and common carp which are bottomfeeders. Other fish will also feed on the excreta of thecommon carp and this helps contribute to the efficiencyof the system which in optimal conditions will produce3000–6000 kg of fish per hectare per year. 9
Integrated recycling systemsOne of the largest problems with freshwater aquaculture is that itcan use a million gallons of water per acre (about 1 m³ of waterper m²) each year. Extended water purification systems allow forthe reuse (recycling) of local water.A hydroponic bed is placed near, above or between them.When tilapia are raised in the tanks, they are able to eat algae,which naturally grows in the tanks when the tanks are properlyfertilized. 10
Classic fry farmingThis is also called a "Flow through system“. . . Troutand other sport fish are often raised from eggsto fry or fingerlings and then trucked to streamsand released. Normally, the fry are raised in long,shallow concrete tanks, fed with fresh streamwater. The fry receive commercial fish food inpellets. ** baby fish are called fry. 11
IssuesMany cultured fishes (tilapia, carp, catfish, manyothers) require no meat or fish products in their diets.Top-level carnivores (most salmon species) depend onfish feed of which a portion is usually derived from wildcaught (anchovies, menhaden, etc.). Vegetable-derived proteins have successfullyreplaced fish meal in feeds for carnivorous fishes, butvegetable-derived oils have not successfully beenincorporated into the diets of carnivores.Secondly, farmed fish are kept in concentrationsnever seen in the wild (e.g. 50,000 fish in a 2-acre(8,100 m2) area.) with each fish occupying lessroom than the average bathtub. This can causeseveral forms of pollution. Packed tightly, fish rubagainst each other and the sides of their cages,damaging their fins and tails and becoming sickenedwith various diseases and infections. This also causesstress. 12
LabelingThe common name on canned fish must be shown inletters of equal height and prominence and indicatewhether the product has been prepared by mincing,flaking or other special process; from selected parts of fishfor dietetic use.>>The geographic location where the fish has beenharvested may be added to the common name,however this is optional. 13
Indoor fish farmingAn alternative to outdoor open ocean cage aquaculture,is through the use of a recirculation aquaculture system(RAS). A RAS is a series of culture tanks and filters wherewater is continuously recycled and monitored to keepoptimal conditions year round. To prevent thedeterioration of water quality, the water is treatedmechanically through the removal of particulate matterand biologically through the conversion of harmfulaccumulated chemicals into nontoxic ones.One of the drawbacks to recirculation aquaculturesystems is water exchange.Because of its high capital and operating costs, RAS hasgenerally been restricted to practices such as broodstockmaturation, larval rearing, fingerling production, researchanimal production, SPF (specific pathogen free) animalproduction, and caviar and ornamental fish production. 14
Slaughter methods H U MA N E I N H U MA N E1.Percussive stunning. 1.Air Asphyxiation.2.Electric stunning : suffocation in the opencan be humane when a air. Takes15 minutes toproper current, duration, induce death.conductivity, and 2. Ice baths / chillingtemperature are present. dampen muscleOne advantage is that in- movements by the fishwater stunning allows fish and to delay the onset ofto be rendered post-death decay.unconscious without 3. CO2 : narcosisstressful handling ordisplacement. 4. Exsanguiation without stunning: taken up from water, held still, and cut so as to cause bleeding. 15