Fish farming
It is a particular type of aquaculture, which is the controlled cultivation and harvesting of aquatic animals such as fish, crustaceans, molluscs and so on, in natural or pseudo-natural environments.
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 (19).
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.
Phytoplankton and algae break down fecal matter and residual fish meal reducing the amount of available oxygen in the water column, which chokes and kills the Benthic organisms.
In these kinds of systems fish production per unit of surface can be increased at will, as long as sufficient oxygen, fresh water and food are provided.
Given concerns of disease, poaching, poor water quality, etc., generally pond systems are considered simpler to start and easier to manage.
Also, the past occurrences of cage-failures leading to escapes, have raised concern regarding the culture of non-native fish species in dam or open-water cages.
On August 22, 2017, there was a massive failure of such cages at a commercial fishery in Washington state in Puget Sound, leading to release of nearly 300,000 Atlantic salmon in non-native waters.
[19] Though the cage-industry has made numerous technological advances in cage construction in recent years, the risk of damage and escape due to storms is always a concern.
In the marine environment, the antimicrobial/algaecidal properties of copper alloys prevent biofouling, which can briefly be described as the undesirable accumulation, adhesion, and growth of microorganisms, plants, algae, tube worms, barnacles, mollusks, and other organisms.
[21] The resistance of organism growth on copper alloy nets also provides a cleaner and healthier environment for farmed fish to grow and thrive.
Each of these alloy types has an inherent ability to reduce biofouling, cage waste, disease, and the need for antibiotics, while simultaneously maintaining water circulation and oxygen requirements.
Fertilizing, clarifying, and pH control of the water can increase yields substantially, as long as eutrophication is prevented and oxygen levels stay high.
Current growers use a variety of proprietary tricks to keep fish healthy, reducing their expenses for salt and wastewater discharge permits.
Some veterinary authorities speculate that ultraviolet ozone disinfectant systems (widely used for ornamental fish) may play a prominent part in keeping the tilapia healthy with recirculated water.
Additionally, fish are genetically engineered to grow larger and faster, leading to health problems such as cataracts and abnormal heart shapes.
Earlier this month, start-ups from places like Pakistan, China, and Belgium joined their American competition at the Google headquarters in Mountain View, California, showing off feed made from seaweed extracts, yeast, and algae grown in bioreactors.
[52] In 2014, Martinez-Rubio et al. conducted a study in which cardiomyopathy syndrome (CMS), a severe cardiac disease in Atlantic salmon (Salmo salar), was investigated pertaining the effects of functional feeds with reduced lipid content and increased eicosapentaenoic acid levels in controlling CMS in salmon after infection with Piscine Myocarditis Virus (PMCV).
Fish fed with functional feeds with low lipid content demonstrated milder and delayed inflammatory response and therefore, less severe heart lesions at earlier and later stages after PMCV infection.
Aquaculturists feel that operating a rearing system above its design capacity or above the social density limit of the fish will result in decreased growth rate and increased feed conversion ratio (kg dry feed/kg of fish produced), which results in increased cost and risk of health problems along with a decrease in profits.
[55] Sea lice, particularly Lepeophtheirus salmonis and various Caligus species, including C. clemensi and C. rogercresseyi, can cause deadly infestations of both farm-grown and wild salmon.
There, juvenile wild salmon must "run a gauntlet" of large fish farms located off-shore near river outlets before making their way to sea.
[70] Additionally, other common drugs used in salmonid fish farms in North America and Europe include anesthetic, chemotherapeutic, and anthelmintic agents.
[78] The high concentrations of fish produce a significant amount of condensed faeces, often contaminated with drugs, which again affects local waterways.
Concern remains that resultant bacterial growth fertilised by fish faeces strips the water of oxygen, reducing or killing off the local marine life.
In regards to genetically engineered, farmed salmon, concern has been raised over their proven reproductive advantage and how it could potentially decimate local fish populations, if released into the wild.
[82] Another method of preventing Aqua Advantage fish from impacting the ecosystems in the case they escape suggested by the FDA was to create sterile triploid females.
[91] From 2011, a team from the University of Waterloo led by Tahbit Chowdhury and Gordon Graff examined vertical RAS aquaculture designs aimed at producing protein-rich fish species.
[102] According to T. Håstein of the National Veterinary Institute (Oslo, Norway), "Different methods for slaughter of fish are in place and it is no doubt that many of them may be considered as appalling from an animal welfare point of view.
"[103] A 2004 report by the EFSA Scientific Panel on Animal Health and Welfare explained: "Many existing commercial killing methods expose fish to substantial suffering over a prolonged period of time.
