**2. Aquatic animal and molecular cloning**

#### **2.1 Major hurdles of aquaculture**

Fish live in a complex 3D environment, so whether it is the density of the fish, or extra feed given by farmer, or local environment and water quality, everything impacts the aquaculture output. Although new concepts like precision fish farming are emerging, the following categories still are a cause of major concern.

#### *2.1.1 Adequate disease diagnosis and health management*

Diseases are the major constricting factor for expansion of aquaculture industry, and they potentially cost the sector nearly \$6 billion in yield loss each year [10]. Aquatic environments impose a constant risk of exposure to disease-causing pathogens and poor knowledge of background microbial "diversity" in aquatic farm systems often leads to frequent emergence of previously unknown diseases. Healthy

**53**

among species.

salmon).

*2.1.4 Improper growth*

*Applied Molecular Cloning: Present and Future for Aquaculture*

looking fish can carry pathogens without a clinical sign and disease become evident only under stressful conditions. Therefore, disease management and assessment of cultured fish is a major concern to commercial aquaculturists. The ability to identify the presence or absence and concentration of a pathogenic organism in fish would have significant economic benefits. Statistically, relevant disease surveillance and monitoring requires testing large numbers of fish as it increases the probability of detecting pathogen from clinically normal fish. Reliable detection of fish pathogens in a fish population is difficult if fish with disease are not available or only a low percentage of the fish is infected. To detect pathogen carrying fish, a cost effective, sensitive, and specific system is required for surveillance and monitoring of fish population. Traditionally, the diagnosis and management of diseases is carried out by culture dependent methods which are slow, require skill, and only selective organism can be detected [11]. Potentially faster, more sensitive diagnostic techniques for identification and characterization of pathogens, even from asymptom-

Since farmed fish are selected and bred for certain genetic criteria like size, quick growth and hardiness, escaped species can become invasive and pose a massive threat to global biodiversity. The ever-growing aquaculture industries also have to bear the public concern in regard to pollution and other environmental effects and thus maintaining and sustaining the environment is of paramount importance. Attention to genetic variability and biodiversity in aquaculture development, proper stock maintenance and aquatic resource management are therefore crucial elements for sustainable environment. In this sense, traceability tools are essential to assess the impact of aquaculture escapees in natural populations or distinguish

Reproduction is crucial for steady and quality seed supply and hence of utmost

Fish growth largely depends on feeding, environment and genetic background.

For example, farmed Atlantic salmon tend to grow faster than wild ones, and genetically modified (GM) farmed salmons are even better. Though FDA recently approved GM salmon, till date it is not ethically preferable to use GM fish for commercial aquaculture. There are few more success stories of using myostatin knockout to improve growth of tilapia, red sea bream and common carp; however, yellow catfish [12] did not display similar results, suggesting functional variation

importance for aquaculture sustainability. Fish gonadal development is influenced by intrinsic (genetics, growth, behavior, etc.), and extrinsic (temperature, hormone, environmental pollution, etc.) factors. Though, large diversity of aqua animals has its own advantages, each species has distinct reproductive and embryonic development biology that hinders the timely breeding and smooth progression of commercial aquaculture. For instance, some gonochoristic fish harbors sex chromosome while others do not, and several commercially lucrative fish sequentially changes their sex. Moreover, some hybrids tend to grow bigger with the expense of reproductive unfitness (e.g., hybrids of Atlantic and pacific

*DOI: http://dx.doi.org/10.5772/intechopen.88197*

atic carrier fish, are of utmost necessary.

the farmed and wild specimens.

*2.1.3 Reproductive medley*

*2.1.2 Maintenance of the environment and biodiversity*

#### *Applied Molecular Cloning: Present and Future for Aquaculture DOI: http://dx.doi.org/10.5772/intechopen.88197*

*Synthetic Biology - New Interdisciplinary Science*

consultancy [6].

biology in fish.

**2. Aquatic animal and molecular cloning**

*2.1.1 Adequate disease diagnosis and health management*

**2.1 Major hurdles of aquaculture**

(integrated multitrophic aquaculture), etc., the probability of sustainable growth of aquaculture has been raised several folds. But, unlike agriculture and livestock farming, aquaculture has lot of geographical restriction, such as in North America and Europe, clams, oysters, and other shellfish are the main species being farmed, while in Japan, edible seaweed, marine shrimp, and yellowtail are the desired species for culture. Likewise, carps in India, freshwater prawns in Hawaii, and eels in Taiwan are the preferred culturable species [1]. Although numerous species (>694) have made their way into aquaculture and have international consumer market, only the Norwegian salmon has gained commercially popularity in recent years. If we analyze deeply, it is clear that it is neither the geographical restriction nor the consumer demand, but rather the huge industrial success of this specific salmon is related to meticulous research, better strain availability through years of selective breeding, authenticated and steady high quality seed availability and one stop

Molecular biology and cloning set sailed its journey with the DNA molecule in 1950s and encountered several breakthrough including RNA and restriction endonucleases, however in reality, the recombinant DNA technology has made a revolution in modern molecular biology. Through this technique, large quantities of proteins present in trace amount, as well as other biologically active substances, could be generated through biotechnology and these genetically engineered macromolecules have very little side effects. Emerging technologies promise even greater possibilities, such as enabling researchers to seamlessly stitch together multiple DNA fragments and transform the resulting plasmids into bacteria in under 2 h, or the use of swappable gene cassettes, which can be easily moved between different constructs, to maximize speed and flexibility. During the past 2–3 decades, fish molecular biology has been intensively investigated in all aspects of fisheries, including diseases, genetics, nutrition, and ecology. Molecular tools are used to investigate changes in the DNA, RNA or proteins to detect certain genetic or biochemical changes that are associated with certain disease-causing pathogens [7–9]. Another advantage of molecular tools is that the analysis can be done on stored specimens and abundance of genetic information in the database. In recent years, great advances have been made to simplify the techniques and reduce the cost without compromising on the sensitivity. In this chapter we will discuss about the issues of aquaculture, and the potential of molecular cloning/

Fish live in a complex 3D environment, so whether it is the density of the fish, or extra feed given by farmer, or local environment and water quality, everything impacts the aquaculture output. Although new concepts like precision fish farming

Diseases are the major constricting factor for expansion of aquaculture industry, and they potentially cost the sector nearly \$6 billion in yield loss each year [10]. Aquatic environments impose a constant risk of exposure to disease-causing pathogens and poor knowledge of background microbial "diversity" in aquatic farm systems often leads to frequent emergence of previously unknown diseases. Healthy

are emerging, the following categories still are a cause of major concern.

**52**

looking fish can carry pathogens without a clinical sign and disease become evident only under stressful conditions. Therefore, disease management and assessment of cultured fish is a major concern to commercial aquaculturists. The ability to identify the presence or absence and concentration of a pathogenic organism in fish would have significant economic benefits. Statistically, relevant disease surveillance and monitoring requires testing large numbers of fish as it increases the probability of detecting pathogen from clinically normal fish. Reliable detection of fish pathogens in a fish population is difficult if fish with disease are not available or only a low percentage of the fish is infected. To detect pathogen carrying fish, a cost effective, sensitive, and specific system is required for surveillance and monitoring of fish population. Traditionally, the diagnosis and management of diseases is carried out by culture dependent methods which are slow, require skill, and only selective organism can be detected [11]. Potentially faster, more sensitive diagnostic techniques for identification and characterization of pathogens, even from asymptomatic carrier fish, are of utmost necessary.
