- Genetic Improvement for Aquaculture
"One Step Away from Full Speed Ahead!"
- Nearly all terrestrial agriculture is conducted with plant
and animal strains that are genetically modified for increased commercial performance, and
showing little resemblance to their wild ancestors (Knibb et al. ,1998).
- The estimated benefit to cost ratios of such genetic
improvement programs range from 5:1 to 50:1. (Gjerde, 1986).
- Aquaculture has so far remained almost untouched by the
advances in applied breeding technology….aquaculture research in general and genetic
improvement in particular have been hampered by short-term, scattered, and disjointed
funding (Eknath et al., 1991).
- It is doubtful that aquaculture will enjoy the success and
productivity of agriculture unless true domestication of the cultured species is obtained.
Genetic applications can direct and speed the process of domestication, providing the
derivatives of [existing] species that are most suited to culture (Manzi et al.,
1989).
- Environmental conditions, and consequently selection
pressures for survival and reproduction, tend to differ between natural and captive
culture environments. Thus, genetically, most marine fish production [and aquaculture in
general] remains equivalent to the use of undomesticated wild ancestral cattle, chicken,
etc. in ancient terrestrial agriculture. (Knibb et al., 1998).
- Aquaculture is agriculture. Along with genetic improvement
should come the gains in industrial efficiency and productivity, in product quality,
consistency, availability and reduction in prices for consumers as reflective of all other
agriculture sectors in which such improvement has been achieved through domestication. The
net benefits are growth and sustainability for the aquatic industry.
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Over the next thirty years the pressure for
applying genetic improvement will intensify for several reasons.
First, population growth will widen the gap
between demand and supply from wild fisheries. Ocean catches have stablized at
approximately 100 million tons per year and future supplies will have to come from
aquaculture. It is estimated that total aquaculture production by 2025 will exceed 60
million metric tons, up from 15 million tons in 1990 (Hempel, 1993).
Second, most aquaculture systems are higher
than normal population density monocultures. These are prone to far greater commercial
losses from disease outbreaks. Losses from existing diseases and new pathogens have been
well documented over the last 10 years. In most cases, the greatest toll has been with
undomesticated stocks of unknown lineage. The development of strains genetically resistant
to important pathogens is one approach for addressing this problem.
Third, future production growth will most
likely shift to intensification wherein output is a consequence of production efficiency
per unit area rather than increases in area of production. Efficient use of capital,
environmental pressure, and unit cost of administration will mandate earlier return on
investment, higher utilization of existing facilities, and reduced exposure to crop
failure from accidental loss or disease, and perhaps better food conversion efficiency as
the primary rules of operation. Genetic improvement produces domesticated stocks more
suitable for captive culture in artificial production environments.
Finally, as with most maturing industries,
as production of any given species increases, competition sets in and there is generally a
convergence of product price with cost of production. This can be seen clearly in the
cases of salmon, oyster, and shrimp aquaculture. Such convergence should be anticipated
for any species under consideration for captive culture. As a consequence, only the highly
efficient and competitive entities will tend to survive and remain profitable in the
narrow window between profit and loss. Genetic improvement is expected to be one of the
most important tools for increasing commercial competitiveness among the survivors.
Genetic improvement provides the capability
of culturing a better quality animal in less time, with greater survival, and at less cost
than animals removed from the wild. |
