India's National Center for Aquatic
Animal Health and Cochin University of Science and Technology
have developed a bacterial consortium delivery system
for aquaculture hatcheries that removes or neutralizes
nitrous waste including ammonia thus avoiding common
industry use of chemical disinfectants and antibiotics.
This organic aquaculture system enhances spawning and
the survival rate of the shrimp larvae. Initial studies
show an increase in shrimp spawn rates of approximately
20% and an increase in larval survival of 46%. This
new system has been developed for management of a larval
prawn seed production system in prawn/shrimp hatcheries
and comprises two bacterial consortium delivery systems
known in the industry as bioreactors, and a pond or
tank water recirculation system. The water recirculation
or closed system hatchery is designed to avoid the introduction
of deadly bacteria and viruses that are often pumped
from infected waters of the wild into open system hatcheries.
This recirculation system enables more consistent water
quality management and fewer incidents of diseases typically
leading to an increased larval survival rate. The system
of nitrifying bioreactors allows the waters of a closed
system hatchery to remain inhabitable by neutralizing
the rapid buildup of waste that exists in a packed shrimp
tank or pond.
The Nitrifying Bioreactor can be used as a stand-alone
product or as a component of an Organic Recirculation
Prawn Seed Production System (ORPSPS) designed to improve
the health of shrimp and eliminate most viral and bacterial
pathogens problematic to shrimp hatcheries.
Potential Benefits of The Technology
Dr. Tzachi Samocha, Professor, Shrimp
Mariculture, Texas Agricultural Experiment Station (TAES),
and Corpus Christi, Texas: "We did extensive research
here on closed hatchery systems and indeed found that
post-larval shrimp produced in a closed hatchery outperform
those in an open system in terms of strength."
Two major components in a hatchery
are the maturation system and the larval rearing tank.
In the maturation system male and female shrimp mate.
When their eggs have hatched, the tiny larvae known
as nauplii are transferred to the larval rearing tank
in which they grow for about 21 days. In the course
of just seven days, the water becomes very dirty due
to organic matter and is not conducive for healthy growth.
Organic matter accumulation leads to secretion of ammonia
and nitrites which are harmful to shrimps even at very
low concentrations. To overcome this problem, hatcheries
practice water exchange, i.e., removal of water in the
tank and addition of fresh sea water. At approximately
21-days old, shrimps called seeds are sold to shrimp
farmers who grow it for between 2 - 3 months till they
attain a certain size and weight and are then sold to
seafood companies.
Dr. Samocha, "In both closed
maturation and larvae rearing systems we definitely
saw improvement of reproductive performance and the
post-larvae's ability to sustain a stress test. The
information out there suggests you will do much better
working with closed systems than an open system's continuous
water exchange if you can indeed develop the bacteria
that can control the bacteria detrimental to shrimp
health."
Sometimes a single virus can travel
and hit all of the shrimp in one pond. Because water
from an open system flows from one pond to another,
it is easy for a blight to hit and severely damage the
shrimp farming industry for a year or two. Bob Rosenbury,
editor of Shrimp News International for 31 years, "I
have seen reports that in the last two years India has
lost $500 million to the white spot virus."
To avoid the introduction of deadly diseases into their
hatcheries, there are specific pathogen free (SPF) certified
brood stock owners may purchase. SPF helps to address
a very severe problem, but it does a hatchery little
good if what they pump into their open systems is water
from the wild that is infected or contains carriers
of these diseases. Dr. Samocha, "Thousands of hatcheries
would use the post-larvae from a controlled closed system
larval rearing facility rather than collecting them
from the wild and running the risk of introducing diseased
animals that will wipe out all of your population in
a matter of days." Bob Rosenbury, "Two years
ago virus free brood stock was selling for $25 an animal,
today they are selling for $100 - $1000 each, and you
need hundreds of these per ten ton tank (shrimp hatcheries
in India may have 40 to 50 such tanks each with typically
larger numbers in Thailand and the U.S.)." Over
95% of larval rearing hatcheries are open system.
Although having low manufacturing
costs is very important, a shrimp farmer or a hatchery
owner can justify additional investment if it reduces
the inconsistent performance and losses associated with
running an open system hatchery. Significant operating
expenses associated with chemical treatment, water temperature
maintenance and other issues would be reduced or eliminated.
Additionally, exposing post-larval shrimp to sudden
changes in water temperature, pH, salinity, different
concentrations of oxygen and other environmental factors
have a significant impact on their survival rate. The
stronger the animal, the better their survival is. These
inherent challenges with open hatchery systems are kept
significantly more manageable in closed hatchery systems.
External growth stimulating media such as vaccines can
be added to stimulate healthy growth. A closed circuit
system ensures that these helpful media directly reach
the shrimps rather than being expelled during water
exchange. Similarly, in the maturation system, the male
and female shrimps are attracted by pheromones. When
water exchange is carried out, the pheromones get diluted
and have an impact of reduced spawning rate.
Nitrifying bioreactor cost:
The average hatchery
in India produces approximately 100 million seeds
(shrimp) per year. This number is somewhat larger
in Thailand and China, respectively first and
third in worldwide shrimp production.
A hatchery producing 100 million
shrimp a year would need approximately 350 tons
of water for a closed system hatchery. Each hatchery
would need about 30 packed bed bioreactors (PBBR)
and 500 stringed bed suspended bioreactors (SBSBR).
Although the bioreactors are
designed to be integrated into hatcheries without
much difficulty, there would be an expense for
the civil and plumbing work to physically accommodate
the reactors.
Hatcheries using tanks or fully
enclosed ponds should see very minimal switching
costs. Hatcheries that are partially open to a
water source would need to establish a barrier
to block any accidental flow of water from the
water source to the pond.
Open system hatcheries converting
to closed system ones should realize savings in
water consumption and pumping expenses.
OABIP states the hardware should
last many years. The bacterial consortium does
not require recharging unless it is removed from
the water.
OABIP states that tests done
in small hatcheries and labs comparing test systems
having the bioreactor and control systems without
the bioreactor show larval relative survival percent
to average 46.4% higher in the test systems with
the bioreactor than the control system without
the bioreactor for both penaeid and non-penaeid
varieties. If at least one-half of this higher
production can be duplicated in larger commercial
hatcheries, the annual revenue for the hatchery
example given would increase $145,000 ($625,000
x 23.2%).
The OABIP system is completely organic-no
chemicals are used as is common in most hatcheries to
control the growth of unwanted bacteria and the spread
of viruses.
Agricultural commodities that are
organically produced typically command a premium of
20% to 30% in the market place. Environmental benefits
of a closed system are also significant. The need to
continually replenish ocean water in open system shrimp
farms has spoiled ground water resources in nearby communities.
This salinized water is also detrimental to traditional
forms of agriculture.
Source:
Mohan Kandaswamy,
Oriental Aquamarine Biotech India P Ltd
E-mail:
orpsps@vsnl.net
