Open Sea Cage Culture
Open Sea Cage Culture
Open Sea Cage Culture
OPEN SEA
CAGE CULTURE
Edited by
K.K. Philipose
Jayasree Loka
S.R.Krupesha Sharma
Divu Damodaran
Handbook on
CONTENT
G. Syda Rao
II
M.K. Sambasivan
VI
P. Vijayagopal
VII Broodstock Development, Breeding &
Larval Rearing of Cobia and Pompano ............................. 59
E.V.Radhakrishnan
XII Fish Growth Parameters and their Monitoring ............... 112
A.P. Dineshbabu
CONTRIBUTORS
1 G. Syda Rao
G. Gopakumar
4 A.P.Dineshbabu
Scientist-in-Charge, Mangalore
Research centre of CMFRI,
Bolar, Mangalore
5 K.K.Philipose
7 M.K.Sambasivan
8 P. Vijayagopal
10 Jayasree Loka
11 Geetha Sasikumar
12 D. Divu
PREFACE
The cage aquaculture has grown very rapidly during the past
20 years and is presently undergoing rapid changes in response
to pressures from globalization and a growing global demand
for aquatic products. Recent studies have predicted that fish
consumption in developing and developed countries will
increase by 57 percent and 4 percent, respectively. Rapid
population growth, increasing affluence and urbanization in
developing countries are leading to major changes in supply
and demand for animal protein, from both livestock and fish.
Within aquaculture production systems, there has been a move
towards the clustering of existing cages as well as toward the
development and use of more intensive cage-farming systems.
In particular, the need for suitable sites has resulted in the cage
culture sector accessing and expanding into new untapped
open-water culture areas such as coastal brackish and marine
offshore waters.
Cage culture of fin fish and shell fish is in the developmental
stages in India. Experimental culture of seabass, mullets and
spiny lobster was carried out at various centres of Central
Marine Fisheries Research Institute with varying degree of
success. Although the results obtained at all the places were
promising, more works are needed to perfect stocking density,
feeding, cage fabrication and cage mooring. The results
vii
K.K.Philipose
Scientist in-Charge &
Course Co-ordinator of
Open sea cage culture
Cage farming
Cage culture has been originated in Southeast Asian countries
and now it is a major culture activity all over the world. Mariculture
in cages began in Japan in the 1950s but developed largely as a
result of the salmon farming industry in northern Europe and
North America during the past two decades. Cages account for
about 60% of coastal fish culture, and if considering Medite
rranean aquaculture, it account above 90% of all seabass and sea
bream production. The main advantages of cages when compared
to conventional land-based systems include low capital costs and
simple management.
Size
It is a fact that costs per unit volume decrease with increasing
cage size, within the limits of the materials and construction
methods used. However, very large cages may limit stocking,
Stocking
Although stocking densities should be determined by species
requirements and operational considerations, the influence of
stocking densities on growth and production has been
determined empirically. The stocking density depends also on
the carrying capacity of the cages and the feeding habits of the
cultured species. Optimal stocking density varies with species
and size of fish. For producing 5 tonnes of 500-600 g seabass
from a 6 m dia. HDPE cage, 30-50 individuals (100 g) per cubic
meter can be stocked.
Harvest
Harvest of fish or lobster in cages is made very easy compared
to that in ponds. Cages can be towed to a convenient place and
harvest can be carried out. Also based on demand, partial or full
harvest can be done.
Cage management
Cage culture management must result in optimizing
production at minimum cost. The management should be so
efficient that the cultured fish should grow at the expected rate
with respect to feeding rate and stocking density, minimize losses
due to disease and predators, monitor environmental parameters
and maintain efficiency of the technical facilities (Chua, 1982).
Physical maintenance of cage structures is also of vital importance.
The raft and net-cages must be routinely inspected. Necessary
repairs and adjustments to anchor ropes and net-cages should
be carried out without any delay. Monthly exchange of net should
also be considered, as this ensures a good water exchange in the
net, thereby washing away feces, uneaten food and to a certain
extent reduce the impact of fouling.
Disease monitoring
Monitoring of fish stock health is essential and early indi
cations can often be observed from changes in behavior, especially
during feeding.
Economic analysis
The success of the adoption of any innovation or new
technology lies in its economic performance. The rate of return
per rupee invested is the economic indicator that guides the
investor to choose a particular enterprise or practice. Besides,
the analysis of the economic performance serves as an indicator
for the investor to allocate his resources in the enterprises. This
becomes very much essential, since the resources are scarce and
the investor is interested to invest his scarce capital resource in
that enterprise that gives the maximum return for his investment.
The economic performance of the cage culture experiment
had been worked out by calculating the annual fixed costs,
variable costs and the annual total costs from the cost side. From
the returns point of view, the harvest from the cage, the gross
revenue from the sales of the product had been worked out.
Using the cost and returns figures, the economic indicators are
estimated to test the economic viability and financial feasibility
of any enterprise. This would serve as guidelines to the
institutional agencies that are extending the financial support to
the enterprise.
Case studies
Demonstration of open sea cage culture for finfish and
shellfish was carried out by CMFRI in Gujarat, Maharashtra,
Karnataka, Kerala, Tamil Nadu, Andhra Pradesh and Orissa.
Lobster culture was successful at Kanyakumari, Vizhinjam and
Mandapam. Asian seabass culture was highly encouraging at
Karwar, Balasore and Chennai. Mullets, seabass and pearl spot
were also successfully harvested from backwater cages at Cochin.
Based on the success CMFRI has developed an open sea cage
Visakhapatnam
Table 1- Initial investment of
the cage culture farm of 1061 m3
Sl.
No.
Items
Investment
(in Rs.)
1
2
3
4
5
6
7
8
9
10
4,00,000
3,00,000
80,000
60,000
1,50,000
1,50,000
25,000
35,000
35,000
2,40,000
% to Economic
total life(in yrs)
27.12
20.34
5.42
4.07
10.17
10.17
1.69
2.37
2.37
16.27
10
10
10
10
50
10
10
10
10
14,75,000 100.00
Details
Depreciation
Insurance premium
(5% of investment)
Interest on fixed capital
Administrative expenses (2%)
1,16,000
73,750
3,96,250
10
1,77,000
29,500
Details
Cost
% to
total
Feeding
Seedling
Feed cost
Net cleaning
Underwater inspection
Net mending and Maintenance
Post crop overhauling
Security
Interest on working capital @6%
for one crop duration
2,24,000
1,50,000
9,00,000
75,000
50,000
25,000
20,000
1,00,000
14.02
9.39
56.32
4.69
3.13
1.56
1.25
6.26
54,040
3.38
15,98,040
100.00
Total
Details
Amount
(in Rs.)
3,96,250
15,98,040
19,94,290
37,50,000
21,51,960
17.55,710
0.43
119%
Balasore
At Balasore, the initial investment for a 6m diameter cage
worked out to Rs.3,00,000. The fixed costs for the culture period
11
3
4
6
7
8
9
10
11
12
13
Amount
(in Rs.)
3,00,000
30,000
3,000
18,000
3,000
54,000
5,0000
1,75,000
6,750
2,31,750
2,85,750
3,032
5,75,760
2,90,010
3,44,010
94.24
189.89
0.50
The culture of sea bass yielded 3.03 tonnes at the end of six
months, thus earning a gross revenue of Rs.5,75,760 to the
participants. The culture has earned a net operating income of
12
Conclusion
Responding to the challenge of filling the gap between
growing demand and capture fisheries supply, mariculture
production has to satisfy the optimistic expectations. Significant
progress is being made by CMFRI in this area through cage
culture as evidenced by both the scientific achievement and the
production trends. The economic analysis of the cage culture
has also been worked out with higher net operating income and
net income in a crop period of seven to nine months. It is to be
13
14
II
Introduction
During the last six and half decades, the potential of aquaculture
for food production were widely recognized and legal policies drafted
in many countries. The development and management of
aquaculture is likely to fall within the scope of various pieces of
legislation and the expertise of various institutions. Aquaculture
activities need to be carefully monitored and controlled because of
the numerous interests involved, the diversity of natural resources
used the variety of institutions concerned, involvement of a wider
range of stakeholders from both public and private sectors. FAO
insist that "9.1.1 States should establish, maintain and develop an
appropriate legal and administrative framework which facilitates the
development of responsible aquaculture" (Code of Conduct for
Responsible Fisheries (CCRF), Article 9).
Indian Scenario
Traditionally, brackish water fishes and shrimps are farmed in
coastal tide-fed ponds by simple extensive system of farming like
the Pokkali farms of Kerala, the Ghazani and Khar of Karnataka
and fish farms (Bheries) of West Bengal. Semi-intensive farming
of shrimps, farming of green mussels and oysters, fattening of
lobsters and crabs, finfish farming, seaweed farming, semi-culture
of clams have increased the production through aquaculture in
coastal ecosystems. The total production (excluding seaweeds) has
increased from 3,868 t in 1980 to 1,97,339 t in 2008. This pheno
menal increase in production indicates the magnitude of utilization
of water resources for coastal aquaculture and mariculture. In spite
of these fast paced developments a policy support to govern the
mariculture development in a sustainable manner has not been
made in the country. Rules and regulations to make shrimp farming
sustainable have been put in place by the Coastal Aquaculture
Authority of India (CAAI) and specific rules have been framed by
some maritime states. The main groups of marine resources which
are farmed in India are the crustaceans, finfishes, molluscs, and
seaweeds. Molluscs such as clams, oysters, mussels and pearl oysters
are mostly sedentary animals hence they are farmed either by onbottom methods by sowing or from suspended floating structures
like the rafts. Recently marine finfish and lobsters farming in marine
cages have also been demonstrated successfully in India. List of
mariculture practices are details in the table below.
16
17
Intertidal/
Sub tidal
Openwaters
MusselsPerna virdis
Intertidal/
Sub tidal
Openwaters
Pearl oysters
Bay/lagoons/
Pinctada fucata
Oceanic
P. margaritefera
open waters
Clams(Papahia malabarica Interdical/Sub
Villorita cyprinoids)
tidal Open waters
Lobsters Panulirus
Near shore
homarus,Thenus orientalis
Finfishes
Open sea
Coastal
fixedcages
Intertidal/
Sub tidal
OystersCrassostrea
madrasensis
Location
Sl. Resource
Lease policiesexist
in somemaritime
states
Lease policiesexist
in some maritime states
Lease policiesexists
states guided by
rulesframed by AAI
Commercial
fattening
Lease policiesexist
in somemaritime states
None
None
None
Experimental
None
(CommercializatonTransitionphase)
Semi-commercial
None
In Kerala,Karnataka
Commercial
in Kerala
Commercialin
Kerala
Commercial
in some Maritime
Land based
(Ponds/cages)
Sea cages
Cages/lanbased
On-bottom
On bottom,
off-bottom(racks,
lines, rafts)
Off bottom
(rafts,cages)
Off-bottom
(Rack andren)
LandBased
(ponds)
18
Policy guided by
Common property
useconflicts
Carrying capacity
Environmental
protection
Conservation
Zonation
19
20
Site Identification
Site Certification
Department of Fisheries
of martime states Moots
proposal and requests
Research Institute
Draft
Lease
Policy
Rule
Research Institute
Flow diagram
of steps and
activities for
devoloping a
mariculture
lease system
in India.
Desing of
Forms
Annuxure
Leasing
Registration
Research
Institute
EIA Post-assessment
Decision on
continues Lease
21
Policy of Framework
The objective of the policy framework is to encourage
responsible open body mariculture in the Indian coastal
ecosystems. It should promote a decision making process that is
transparent, efficient, coordinated and credible with the entire
process taking 3-4 weeks. It should employ a precautionary
approach to avoid and minimize environmental impacts and
promotes integration into the ecosystem.
It should be consistent with existing Indian laws and Agency
responsibilities and be consistent, to the maximum extent
possible, with the coastal water environmental and aquaculture
policies of adjacent nations; also consistent with Indias obligation
under International agreements. The policy should be adaptive,
and should promote the opportunities for innovation, data
collection and continual learning
Certain mariculture practices like the pearl culture and cage
farming can be done only in bays and open sea areas which are
protected and not affected by cyclones and oceanic disturbances.
One of the major impediments in development of mariculture
in open access water bodies is the lack of protection of the farm
structure. State Governments in consultation with competent
research institutions can demarcate selected areas congenial for
mariculture as "Mariculture Parks". Those who are interested to
invest in mariculture can apply for lease in these mariculture
parks and after the approval by the competent authority they
will have ownership over the allotted area for the specific time
period. There are various Monitoring and Administering
Agencies involved in various legislatures and mariculture
entrepreneurs has to be need to be given guidelines to abide by
the different legislations by different organizations.
22
Responsibilities
Ministry of Agriculture
Ministry of WaterResources
Ministry of SurfaceTransport
Ministry of Petroleumand Natural Gas
Ministry of Tourism
Ministry of mines
Management of resources in
the coastal water
Scientific monitoring of the
marine
environment,management
of resources in the high seas
Development of fisheries,
aquaculture, fish processing
Erosion
Ports, shipping etc.
Offshore installation, coastal
refineries, pipelines etc.
Tourism activities in coastal
regions
Mining activities in coastal
regions
23
Relevant Acts,
programmesand policies
Offers protection to
fisheries againstexplosives
or dynamites
Protection to marine
biodiversity
24
1991 (underEPA,1986)
Coastal Regulation
ZoneNotification
Regulations on various
activities in coastalzone.
1995 UNCLOS
Supreme CourtIntervention
Plans (CZMPs) that all the
Coastal states prepare
their CZMPs by1996.
25
the country, perhaps due to the lack of a policy for usage of open
water bodies. The coastal areas of the country are densely populated
and their major occupation is related to fishing and ancillary activities.
Therefore, demarcation of suitable areas for a relatively new venture
such as mariculture may invite multi user conflicts. Therefore, to
initiate such projects, it is very important to involve the local community and frame suitable policy for aquaculture. Coastal Aquaculture
in the open waters requires statutory support and the Government
is yet to take major policy decision in this regard. Therefore, any
major effort for commercialization of the technology for mariculture
of various species will depend on an effective policy framework.
26
III
Site Selection
Site selection is the most important factor which determines
the commercial viability of mariculture systems. Cage culture
can be made possible only when the site for cage culture operation
is located, designed and operated to provide optimum water
quality and to avoid stress conditions. In addition to water and
sediment quality of the site some biological and natural
distribution information for the species should also be known
before a site is selected for cage culture. The selection of fish for
cage culture should be based on biological criteria, such as
physiological, behavioural characteristics and level of
domestication; marketing criteria and environmental criteria,
distribution and habitat of site (Fig. 1).
COMMUNICATION
management
fry
feed
harvest
PRODUCTS
alive
frozen
other process
export
opportunity
SOCIO -ECONOMIC
STATUS
population
occupation
socio-economic
status
BACK-UP
FACILITIES
WATER
QUALITY
FRY AVAILABILITY
closes season
import limit
CLIMATIC
CONDITIONS
IMPACT
ecological
socio-economical
CONFLICTS
navigation
recreational fisheries
future coastal development
conservation
POLLUTION
LEGISLATION
maritim law
domestic
agricultural
industrial
28
Topographical criteria:
The cage site to be selected should be of a suitable depth,
have good tidal flow with optimal conditions and ideally be
protected from strong winds and rough weather and have
sufficient water movements. The size of wind generated waves is
determined by (i) wind velocity, (ii) the duration of time that
the wind blows, and (iii) the distance of open, unobstructed
water across which the wind blows (fetch) (Bascom, 1964). In
general, the wind velocity should be less than 5 knots for
stationary cage and 10 knots for floating cage. The height of the
wave should be less than 0.5 m for stationary cage and 1.0 m for
floating cage. Culture sites should be placed at some distance
from navigation routes as the waves may be created from the
wake of passing vessels.
It is necessary to allow sufficient depth under the cage in
order to maximize water exchange, avoid oxygen depletion,
accumulation of debris and build up of some noxious gases
generated by decomposition of the deposited wastes. In turbid
water, silt will tend to accumulate in the cage preventing good
water exchange. The minimum and maximum depth of the cage
can be calculated as follows:
D2
D2
M
T
H2
=
=
=
=
=
M - T + H2
minimum depth at lowest low water during spring tide
measured depth
tidal height at the time when M is taken
minimum tidal height at lowest low water during
spring tide
Bottom condition
For an ideal site for cage culture, a firm substrate, with a
combination of fine gravel, sand and clay will be highly
productive. Depending on the type of substrate present at any
29
given site type of cages also vary. The floating net cages over
rocky substrates require more expensive anchoring blocks, but
have better water exchange rate. In general, sloping areas from
the shore leading to flat bottoms are suitable for cage culture
because the waste build-up at the bottom is easily eliminated.
Additional site selection criteria should also include accessibility
to the cages and the ability to move them out of potential harmful
events such as algal blooms and/or low DO events. Continuous,
unattended monitoring systems that can send alerts when
conditions are close to unacceptable ranges are invaluable in these
situations.
Physical criteria
The main physical parameters that need to be considered in
cage culture systems include factors such as current movements,
turbidity and water temperature.
30
31
culture area, nitrite level should not exceed 4 mg/litre while nitrate
level should be below 200 mg/litre. The excessive amount of
nitrite in water becomes toxic to fish due to oxidation of iron in
haemoglobin from ferrous to ferric state (Tiensongrusmee, 1986).
It will cause hypoxia in fish because haemoglobin molecule
cannot bind with oxygen.
Biological criteria
Phytoplankton: Although a few tropical marine species of
Cyanobacteria are toxic (eg. Lyngba and Oscillatoria, Moore,
1982), their blooms are uncommon. A number of marine algae
groups form blooms, including diatoms, Cyanobacteria,
prymnesiophytes and dinoflagellates. Chaetoceros convolutus has
a number of prominent spines which interfere with gill function
and loss of blood from injury (Kennedy, 1978). Excessive blooms
of phytoplankton can happen whenever the suitable condition
32
33
High-valued species
a.
b. As the fish can be easily harvested live, the farmer can sell
the produce in prime, live condition. In doing this, he
obtains a better price for the fish than would be possible if
they were sold chilled or frozen as is the usual case in pond
culture.
c.
Lutjanus argentimaculatus
Acanthocephalus Iatus
Trachinotus blochii
Raccchycentron canadum
Lates calcarifer
Source :
FAO: UNDP/FAO Regional seafarming development and demonstration
project in Asia NACA-SF/WP/89/13. Site selection criteria for marine finfish
net cage culture.
FAO: Regional sea farming project. RAS/86/024. Training Manual on Marine
Finfish Netcage Culture in Singapore. Species selection, culture and
economics.
36
IV
DEVELOPMENT OF INNOVATIVE
LOW COST CAGES FOR
PROMOTING OPEN SEA CAGE
CULTURE ALONG
THE INDIAN COAST
K.K. Philipose and S.R. Krupesha Sharma
Introduction
37
6 m dia cage
Total cost of this cage including
material, fabrication, epoxy coating,
floatation and outer and inner net
comes to Rs. 100,000 only. This
design makes cage farming
affordable for fishermen all
along the west coast
38
Inner net
(4.5 m depth)
Outer net
(5 m depth)
6 m dia
7 m dia
39
Design
The low cost cage developed at Karwar is made of good quality
1.5" GI pipe (B class). The design details of the cage are given in
fig-(1) and Fig-(2). The diameter of the cage is 6 m and the
height is 120 cm from base to the railings. Fig (3). All the joints
are double welded for ensuring extra strength. After fabrication
the structure was provided with single coat epoxy primer and
double coat epoxy grey paint to prevent rusting. The total weight
of the cage is about 700 kg.
Floatation
Puff or foam field HDPE cage is buoyant enough to float in
the water. However, metal cage needs additional floatation (Fig.4).
Ten fiber barrels of 200 l capacity filled with 30 lb air are used for
floating the cage. The cage when floated on inflated barrels provides
a stable platform around the cage where fisherman can stand and
safely carry out works like net clearing, net replacement etc.
Disadvantages
Unlike HDPE cage wind action is more on metal cage as it is
floated on barrels. Hence, it will be difficult to float in open sea
condition from June to August unless heavy duty mooring is
provided. Except for this the metal cage performance is far
superior to HDPE cages.
41
DIFFERENT TYPES OF
NETTING MATERIALS &
THEIR PROPERTIES
M.K. Sambasivan
42
2 PLY
3 PLY
4 PLY
6 PLY
9 PLY
12 PLY
15 PLY
18 PLY
24 PLY
27 PLY
30 PLY
36 PLY
45 PLY
54 PLY
72 PLY
210/1X2
210/1X3
210/2X2
210/2X3
210/3X3
210/4X3
210/5X3
210/6X3
210/8X3
210/9X3
210/10X3
210/12X3
210/15X3
210/18X3
210/24X3
1
2
3
4
5
6
7
8
9
0.10mm
0.12mm
0.16mm
0.20mm
0.23mm
0.28mm
0.32mm
0.40mm
0.50mm
Nylon fishnets
(I) Nylon Multifilament Fishnets Knotless & Knotted
(II) Nylon Monofilament Fishnets
Nylon Multifilament fishnets are commonly used for the
fabrication of various types of gill nets, ring seine, Purse seine,
Cast net, Chinese nets, Drift nets etc.
43
44
Code
Apprx.Dia.
Apprx.
Runnage
(Mtrs/Kg)
Apprx.
Br.strength
(in Kgs)
280D/1/3
0.25mm
11100
280/2x3
0.50mm
5490
280/3x3
0.75mm
3080
280/5x3
1.00mm
1890
15
280/6x3
1.25mm
1612
18
300D/8x3
1.50mm
1200
24
300/12x3
2.00mm
802
36
300/21x3
2.50mm
432
63
300/28x3
3.00mm
342
84
45
46
VI
47
called essential amino acids and the remaining 10 are called nonessential amino acids. Essential amino acids are those which cannot
be synthesized by the animal at a rate required for the normal
growth of any organism and so they have to come through food.
Non-essential amino acids are the amino acids which can be
synthesized by the animal in case they are not available through
the food. Therefore, proteins are essential for growth of the animal
and a deficiency can lead to what can be called as sub-normal
growth. Other than the growth promoting role of protein they
are required for the normal immune function of the animals
preventing them from disease attack. Most of the enzymes present
in animals are proteins, there are protein hormones, and there are
structural proteins like keratins. In short protein have multiple
functions in the animal body among which growth can be
considered to be the most important.
Carbohydrates (starch and sugars) are energy yielding
components in food. Even though fishes do not have an absolute
requirement of carbohydrates, they are used in fish feeds for
imparting several functional properties to pelletized feed like
buoyancy, that is, sinking, slow sinking and floating properties to
the pellet.
Fat are also energy yielding components if food. The quantum
of energy available from fat is 2.5 times more than the energy
available from carbohydrates. Fats are made up of fatty acids, among
which, a few are considered essential (essential fatty acids). These
fatty acids have to be supplied through feed.
The aforementioned three components of feed are called
macronutrients because they make up the major chunk of the
feed. Minerals and vitamins are called micro nutrients because
they are required only in small quantities in the feed.
Minerals generally looked at in feeds are Calcium (Ca),
Phophorus (P) which are called macro minerals because of their
relatively high levels of inclusion. Other minerals, Copper (Cu),
Cobalt (Co), Iron (Fe), Sulphur (S), Iodine (I), Magnesium (Mg),
48
Crude
Crude fat Crude
or Ether
Fiber
Moisture protein
(CP) Extract (EE) (CF)
<12
<12
<12
<12
>42
>40
>38
>35
>5
>5
>5
>5
<4
<4
<4
<4
Feed ingredients
Feed ingredients used for making feeds can be classified as
protein rich ingredients which are mainly fish and meat products
of animal origin and oilcakes of plant origin. Energy rich
ingredients are mainly cereals and cereal by products. Other than
these there are non-conventional feed resources (NCFR) which
are used in feed manufacture.
50
Moisture
%
rice bran
10.0
rice polish
10.0
wheat bran
8.0
groundnut cake
10.0
sunflower cake
9.0
mustard cake
9.0
sesame cake
9.0
rapeseed cake
10.0
salseed cake
9.0
cotton seed cake
8.0
rubber seed cake
9.0
copra cake
12.0
soybean cake
9.0
palm kernel cake
9.0
tamarind seed cake
9.0
black gram husk
9.0
green gram husk
9.0
mulberry leaf
10.0
ipomoea leaf
12.0
ipil-ipil (leucaena)
8.0
Tapioca leaf meal
12.65
Crude protein
%
8.0-12.0
10.0-14.0
12.0-14.0
40.0-42.0
30.0-32.0
30.0-35.0
32.0-36.0
30.0-35.0
8.0-10.0
35.0-40.0
30.0-35.0
20.0-24.0
45.0-50.0
12.0-14.0
13.0-15.0
24.0-26.0
24.0-26.0
24.0-27.0
16.0-20.0
18.0-21.0
34.37
Crude fat
%
8.0-10.0
10.0-16.0
2.0-3.0
6.0-8.0
4.0-6.0
7.0-9.0
7.0-10.0
2.0-3.0
2.0-3.0
3.0-5.0
10.0-15.0
6.0-8.0
1.0-2.0
5.0-7.0
6.0-8.0
10.0-15.0
3.0-5.0
2.0-4.0
2.0-4.0
4.0-6.0
5.93
Crude fibre
%
12.0-20.0
8.0-10.0
10.0-12.0
10.0-12.0
15.0-20.0
10.0-15.0
10.0-14.0
12.0-14.0
3.0-5.0
11.0-13.0
7.0-8.0
12.0-14.0
8.0-10.0
25.0-28.0
13.0-15.0
8.0-10.0
5.0-7.0
10.0-12.0
9.0-10.0
5.0-7.0
15.73 5.05
Ash
%
15.0-19.0
5.0-6.0
4.0-6.0
3.0-4.0
5.0-7.0
7.0-9.0
8.0-10.0
5.0-7.0
8.0-10.0
6.0-8.0
8.0-10.0
5.0-6.0
7.0-8.0
3.0-4.0
3.0-4.0
40-6.0
5.0-6.0.
6.0-8.0
8.0-10.0
8.0-9.0
26.27
NFE % Nitrogen
(free extract)
35.0-40.0
40.0-45.0
50.0-55.0
25.0-28.0
35.0-40.0
30.0-35.0
20.0-25.0
30.0-34.0
65.0-70.0
25.0-28.0
32.0-36.0
40.0-43.0
30.0-35.0
42.0-46.0
60.0-65.0
30.0-34.0
30.0-35.0
45.0-48.0
45.0-48.0
48.0-52.0
Table 1.Proximate composition of selected feed ingredients of plant origin in India (%)
51
14.5
12.2
11.4
12.0
12.6
7.8
2.9
9.4
12.1
15.8
13.5
8.2
12.6
11.5
14.5
28.6
37.7
42.0
46.6
35.8
48.0
31.0
30.1
12.2
46.3
52
17.3
16.0
15.3
4.2
11.3
6.1
5.0
4.7
1.3
4.3
2.6
6.6
7.5
1.9
3.7
13.8
11.5
7.3
7.7
8.5
2.0
2.1
2.9
4.9
1.3
Ash
7.5 n.a.
9.0
6.0
11.0 12.9
5.3
3.1
19.3 10.2
14.4 20.5
18.0 27.3
13.5 31.4
15.2 23.8
8.7 n.a.
12.2
3.0
33.5
4.2
11.9
4.2
4.0
0.2
2.7
2.3
7.5 13.4
13.2
7.3
13.0
2.5
6.5
7.7
8.2 10.5
11.2
2.7
18.4
1.5
24.7
6.5
25.6
2.6
5.0
n.a.
Nitrogen
free extract
n.a.
46.8
41.0
65.4
36.5
43.4
38.4
32.3
40.4
n.a.
58.7
34.5
54.5
73.4
64.2
28.9
24.3
25.2
23.2
29.9
29.1
39.0
25.6
45.8
n.a.
Soybean meal
Soybean meal
Soy sauce waste
Rapeseed cake
Salseed cake
Sesame cake
Sesame cake
Sesame cake
Mustard cake
Mustard cake
Cotton seed cake
Cotton seed cake
Gingely cake
Gingely extr.
Niger extr.
Copra cake
Copra cake
Copra cake
Tobacco seed extr.
Maize meal
Maize
Sorghum
Spirulina
Tapioca flour
Tapioca flour
Coffee pulp
Colocasia meal
Eichornia meal
Pistia meal
Leucaena meal
Mulberry leaf, dry
Salvinia meal
3.0
10.0
12.0
11.0
8.6
8.3
10.0
10.0
8.5
9.2
7.0
8.2
9.0
7.0
7.0
12.0
8.4
n.a.
7.7
13.5
10.4
10.0
8.7
11.5
8.0
12.3
5.8
3.3
4.9
11.8
8.9
2.6
58.6
46.0
13.5
35.9
8.2
41.9
29.0
42.7
30.8
23.6
37.0
42.7
34.0
40.0
35.0
22.0
20.3
22.0
30.6
9.5
4.6
9.0
50.5
3.1
1.8
14.0
24.6
19.5
19.5
33.1
27.7
16.2
53
1.4
0.9
8.2
0.9
2.9
9.2
12.9
6.9
9.3
9.6
6.7
1.0
7.8
2.0
2.0
6.5
11.4
6.0
0.3
4.0
7.8
2.8
1.0
2.3
1.3
1.2
4.5
2.3
1.3
4.7
2.4
1.1
0.4
7.3
5.8
13.2
1.7
6.2
18.3
5.7
6.2
6.3
13.0
12.6
7.9
9.7
19.0
12.2
16.2
12.0
4.0
3.5
3.0
2.1
2.0
1.8
20.8
8.2
18.3
11.7
9.0
11.5
18.5
5.3
0.6
5.3
6.9
10.2
14.8
10.0
12.9
10.3
10.4
1.0
8.2
3.1
2.9
3.5
5.2
6.2
2.1
13.7
1.5
1.0
0.1
11.0
2.3
0.2
8.2
9.9
9.3
25.6
7.2
8.1
22.0
31.3
35.2
55.2
32.1
68.4
19.6
19.8
21.8
34.9
40.9
35.3
27.3
38.2
38.4
33.5
42.1
37.5
n.a.
47.7
67.5
72.7
75.1
26.7
78.8
86.9
43.5
47.0
47.3
37.0
34.2
41.4
39.6
64.4
53.6
56.1
47.8
72.0
50.0
45.0
28.0
22.5
34.2
28.3
46.0
75.0
52.0
50.7
43.9
68.0
65.3
76.6
50.0
71.2
65.0
5.0
51.7
54
7.5
0.3
5.4
3.1
2.5 17.8
10.3
2.6
10.0
0.5
7.0
1.0
8.0
1.2
2.7 12.5
3.6 35.3
6.7 12.2
1.1
7.1
2.6 13.5
6.5
4.0
11.6
5.5
8.9
3.9
25.7
4.2
2.6
1.3
0.5 n.a.
1.1
1.0
4.4
6.8
13.3
0.7
3.4
1.2
3.4
12.8
Ash
Nitrogen
free extract
19.2
20.9
2.5
18.3
n.a.
4.0
6.0
n.a.
18.6
27.9
31.6
18.0
n.a.
n.a.
6.4
15.8
7.2
n.a.
3.8
5.0
n.a.
2.4
7.5
11.9
7.0
n.a.
29.0
29.8
n.a.
11.0
15.4
16.3
5.8
n.a.
n.a.
22.0
3.3
12.8
n.a.
4.6
25.8
n.a.
21.0
12.5
14.6
97.02
94.66
94.85
94.92
89.93
91.64
96.39
94.56
DM
2.98
5.34
5.15
5.08
10.07
8.36
3.61
5.44
Moisture
47.35
61.74
45.00
67.60
11.15
52.09
68.98
84.75
CP
3.21
3.39
3.45
7.52
1.29
0.51
3.42
5.62
EE
45.57
23.97
40.26
9.12
0.59
7.85
17.59
4.53
CF
0.729
0.13
7.02
0.30
1.84
6.95
3.08
0.31
NFE
AIA
3.14 2.37
10.77 1.63
4.27 16.92
15.46 2.95
85.13 0.08
32.6
0.02
6.93 1.67
4.79 00.05
Ash
100
20
60
120
160
80
100
Cost
INR kg-1
Table 4.Proximate composition of feed ingredients (analyzed values% on Dry matter basis)
Handbook on Open Sea Cage Culture
55
Feed formulation
With a fair knowledge of nutrients and the feed ingredients,
the next aspect to be understood is the need for blending of feed
ingredients to have a nutritionally complete and balanced feed
mix. As is the case in human nutrition, when feed material is
blended the food that is consumed will be balanced in terms of
nutrients and complete in terms of nutrition. For eg. Plant
proteins are deficient in sulphur containing amino acids like
cysteine and methionine. Animal proteins are rich in both these
amino acids. Similarly, plantz proteins are rich in calcium and
poor in phosphorus and cereals are poor in calcium and rich in
phosphorus. Likewise many examples can be seen in nature. In
essence, mixing of feed ingredients takes care of these imbalances
and when done with a scientific basis a nutritionally complete
feed can be made which will be effective in producing the desired
results in terms of fish production.
In feed formulation, when we mix two ingredients in equal
proportion, the resulting mixture will have only 50% of the
nutrients contained in each. Suppose, a mixture of groundnut
oilcake (GNOC) containing 45% protein is mixed with rice
bran (RB) containing only 10% protein in equal quantities the
mixture will contain only 22.5 + 5 = 27.5% protein. If we vary
the percent composition to 60% GNOC and 40% RB then the
mixture will contain 27 + 4 = 31% protein. Let us not forget
that this is applicable to all other nutrients present in these two
ingredients. From this simple scenario, we will be able to visualize
complex scenarios which will contain more ingredients and more
no of constraints. Such scenarios can have only mathematical
solutions which can be solved in a simple Excel spreadsheet which
56
Feeding
Feeding rates, feeding frequency and time of feeding are all
important factors to be considered in feeding of the fish. As a
general rule of the thumb most of the vertebrates including fish
consume 2.5 to 3.0% of the body weight in dry matter. Feeding
rates and frequencies are related to fish growth. Small larval fish
and fry need to be fed a high protein diet frequently and usually
in excess. When fishes grow bigger, feeding rates and frequencies
should be lowered. Feeding fish is a labour intensive activity and
feeding frequency has to be programmed in such a way that it is
economically viable. Generally growth and feed conversion
increases with increase in feeding frequency. Apart from this many
57
other factors affect feeding rates in fish. Feeding of the fish is also
influenced by the time of the day, season, water temperature,
dissolved oxygen levels and other water quality variables. Even
though, several feeding charts are available it is better to construct
one of your own with information on Days after stocking, Fish
weight, Protein in feed, Meal/day, Feed consumed as % of body
weight, Average daily gain(ADG) and Feed conversion ratio (FCR).
58
VII
BROODSTOCK DEVELOPMENT,
BREEDING & LARVAL REARING
OF COBIA AND POMPANO
G. Gopakumar and A.K. Abdul Nazar
60
Quarantine treatment
Upon arrival at the hatchery, broodstock fishes are released
into the quarantine tanks for prophylactic treatment. Fish
Anaesthetics like MS 222 (50-100 ppm), Aqui-S (4 ml / 100 L),
2-phenoxyethanol (200-300 ppm) and quinaldine dissolved in
acetone (3-5 ppm) can be used for broodstock handling. The
prophylactic treatment is given to limit the risk of introducing
parasites or bacterial diseases into the hatchery facility. Short
time exposure of brooders (5 15 minutes) in freshwater will
help to remove the external parasites. The prophylactic treatment
in hatcheries includes a sequence of medicated baths in formalin,
malachite green and Oxytetracycline. Prophylactic treatment can
be repeated three to four times within a week.
61
Broodstock Feeding
For quicker maturation, the broodstock fishes are to be fed
with highly nutritive diet. Diet rich in vitamins, poly-unsaturated
fatty acids (n- 3 PUFA) and other micro-nutrients is essential
for obtaining viable eggs and larvae. The brood fishes can be fed
ad libitum once a day with chopped oil-sardines, crabs, shrimps
and squids stuffed with vitamin, micro- and macro- nutrient
premixes.
Tagging of Fish
Tagging or physical marking of broodstock fishes through
easily detectable methods is very much essential for selection of
broodstock for identification, selective breeding and segregation.
The most popular method is Passive Integrated Transponder
(PIT) tagging. PIT tagging also known as microchips is a radio
frequency device to permanently mark fishes internally. The tag
is designed to last the life of the fishes providing a reliable, long
term identification method.
Induced spawning
Spawning can be obtained either by natural or inducing with
hormonal treatment. Induced breeding is commonly practiced
in most commercial hatcheries. The hormonal treatment is
intended to trigger the last phases in egg maturation, i.e. a strong
egg hydration followed by their release. However, if eggs have
not reached the late-vitellogenic (or post-vitellogenic) stage, the
treatment does not work; hence ovarian biopsy is essential for
assessing the ovarian development. The human chorionic
64
Spawning tanks
The spawning unit should preferably be kept separated from
the main hatchery building to avoid disturbance to the spawners
and possible risk of disease contamination. However, for
economic reasons, it is usual to keep the brooders inside the
hatchery in a specific dedicated area. Though we use only
rectangular tanks based on availability, it is preferable to use
65
Egg harvest
The fertilized eggs of cobia and pompano float and are
scooped gently using 500 m net. To minimise the presence of
poor-quality eggs, which usually float deeper in the water, it is
advisable to collect only the eggs found at the water surface. The
egg samples must be thoroughly examined to assess their quality,
number and development stage using a microscope.
Incubation of eggs
Incubation of eggs can be carried out in incubation tanks of
3-5 tonne capacity. Stocking density can be maintained at a
moderate level of 200 to 500 eggs per litre. After hatching, only
the hatched fish larvae have to be moved to the larval rearing
tanks filled with filtered seawater. Prior to this, the aeration should
be stopped briefly to enable the debris and exuviae to settle at
the bottom which can be removed by siphoning. The
development of embryo can be observed at frequent intervals
under a stereo/compound bionocular microscope. The hatching
of eggs takes place from 18 to 24 hours.
Larviculture
Newly hatched larvae have to be checked to assess their
viability and condition prior to stocking in the larviculture tanks.
At least 10 to 20 fish larvae have to be observed under the
microscope for the following:
shape and dimensions
deformities, erosions and abnormalities
66
Larviculture of cobia
Newly hatched larvae of cobia normally measures 3.4 mm
size. Larval mouth opens at 3-5 days post hatch (dph).
Metamorphosis starts from 9-11 dph. Newly hatched cobia larvae
generally start feeding at 3 dph and they can be fed with the
enriched rotifer (Brachionus rotundiformis) at the rate of 10-12
nos / ml, four times a day till 10 dph. From 8 dph, the larvae can
be fed with enriched Artemia nauplii at the rate of 1-3 nos / ml,
2-3 times per day. During the rotifer and Artemia feeding stage,
green water technique can be used in the larviculture system
with the microalgae Nannocloropsis occulata at the cell density of
1x105 cells / ml. The weaning to artificial larval diets has to be
started from 15- 18 dph. While weaning, formulated feed should
be given 30 minutes prior to feeding with live feed. Size of the
artificial feed has to be smaller than the mouth size of the fish.
Continuous water exchange is required during weaning stage.
Between 25-40 dph, the larvae are highly cannibalistic and hence
size-grading has to be undertaken at every four days interval.
During this stage, the fry could be weaned totally to artificial
diets. Larval rearing can be practised both intensively in tanks
and extensively in ponds. The major factors affecting the growth
and survival of larvae are nutrition, environmental conditions
and handling stress. Since there is high demand for essential
fatty acids (EFAs), enrichment protocols are needed for live67
feeds. The water exchange can be practically nil till 7dph and it
can be gradually increased from 10-100 % from 8 to 12 dph.
The environmental conditions required during the larviculture
period are DO2 : > 5mg / l , NH3: < 0.1mg / l, pH: 7.8 8.4,
Salinity: 25-35 ppt, water temperature : 27-33 C.
Green water has to be maintained in appropriate densities in
the larval tanks. While weaning the fish larvae from rotifers to
artemia nauplii, co-feeding with rotifers has to be continued
due to the presence of different size groups of larvae. The detail
of weaning protocol is as follows.
Size of Feed ()
100-200
300-500
500-800
800-1200
Larviculture of Pompano
The newly hatched larvae are stocked at a density of 10000
larvae in FRP tanks of 2 m3 capacity filled with 1.5 m3 filtered
seawater. The tanks are provided with mild aeration and green
water at a cell density of 1 x105/ml. The mouth of the larvae
opens on 3 dph and the mouth size was around 230 .
68
The larvae are fed from 3 dph to 10 dph with enriched rotifers
at a density of 5-6 nos. per ml, wherever possible, wild collected
copepods could also be added as supplements. Enriched Artemia
nauplii are provided at a density of 1-2 nos. per ml from 8-19
dph. Weaning to larval inert feeds was started from 15 dph. From
25 dph onwards, feeding can be entirely on larval inert feeds. The
metamorphosis of the larvae starts from 18 dph and all the larvae
metamorphose into juveniles by 25 dph. Critical stage of mortality
would occur during 3-5 dph and subsequent mortalities are
negligible. The water exchange can be practically nil till 7dph and
it can be gradually increased from 10-100 % from 8 to 14 dph.
Copepod culture
Copepods have almost become inevitable because they are
the only acceptable sized prey for small larvae of many marine
69
fin fish species and the only type of live feed that will support the
altritial type of larvae. Copepod nauplii offer a diverse size spectra
and nutritious prey that can meet the specialized needs of small
fast growing fish larvae. Over the past few years, several articles
have been published and many conferences were dedicated to
discussions of copepod culture and the important role that
copepods can play as live feed for marine finfish larviculture.
Rotifer culture
Rotifers are the smaller size zooplanktons widely used in
marine fin fish hatchery operations. The marine fin fish larvae
initially feeds on the such smaller size zooplanktons and hence
suitable size of rotifers need to be cultured in mass to feed the fish
larvae. The important criteria for selecting the rotifer depends on
the mouth size of the fish larvae, digestibility, nutritive value of
the rotifer and easy for culture and proliferation. Marine and
brackish water rotifer species can be artificially propagated in
seawater and more popular rotifer species used for marine fin fish
hatcheries are Brachionus plicatilis and Brachionus rotundiformis.
Based on the length of lorica, Brachionus is separated into 3
strains: B. plicatilis as L type (large) with long of lorica 200
360 m; B. rotundiformis as S type (small) with long of lorica
150 220 m; B. rotundiformis as SS type (super small) with
long of lorica 70 160 m.
Artemia nauplii
Having a larger size than rotifers, the nauplii of brine shrimp
Artemia are used as the second live food to fed fish larvae.
Commercially available Artemia cysts are purchased and hatched
whenever required. The first Artemia larval form is the nauplii,
which are smaller in size and richest in yolk, and followed by
larger size metanauplii, whose nutritional value has to be boosted
by feeding them with special enrichment diets 12 to 24 hours
before feeding them to the fish larvae.
70
71
VIII
NURSERY REARING
OF ASIAN SEABASS
S.R.Krupesha Sharma,
Praveen Dube and K.K.Philipose
Overview
72
73
74
75
76
IX
TRANSPORTATION OF
FINGERLINGS AND JUVENILES
OF MARINE FINFISH
Jayasree Loka and K.K. Philipose
77
The basic factors and principles associated with any live fish
transport systems are evaluated before the actual ways of fish
transport are commented on. The transportation of live fish
involves the transfer of large numbers (or biomass) of fish in a
small volume of water. During transportation, fish are subjected
to handling stress and may die, if survive, growth of fish may be
affected. The principles governing packaging, handling and
transportation of live fish are essential to minimise stress.
78
80
Seabass
Biomass g/L
Transport water
temp. (C)
811
100
89100
79
2829
1114
50
102128 45
2829
1117
50
147
45
2829
4.55
70100
50100
1120
2728
>510
60100
93148
1435
2528
>1015
50100
94180
816
2728
>1520
50
133
2728
>2030
3560
200300 710
2728
>3040
3540
222267 67
2728
>4050
35
292
2728
>5070
25
267
2728
105
2025
525
2728
81
Method II
Measure about 3 times the fish weight of filtered seawater
(eg. if fish is 600 g, measure about 1.8 litres of seawater) and
pour into a plastic bag.
Transfer the fish gently into the bag.
Calculate the volume of cooled (18C) filtered seawater required
to cover the fish (weight of seawater = 3 wt. of fish).
Pour the water into the plastic bag.
82
Source:
Berka, R., 1986.The transport of live fish.A review. EIFAC Tech.Pap.,
(48):52 p.
FAO. Training Manual on Marine Finfish Netcage Culture in Singapore
Regional seafarming project RAS/86/024
83
MUSSEL FARMING
Geetha Sasikumar and K.S.Mohamed
Introduction
Site-selection
The success of mussel mariculture depends largely on the
selection of an ideal culture site. Selection of an appropriate
culture site shall be based on careful consideration of a number
of factors that are critical to the species selected. The range of
tolerance of the selected species to various environmental
parameters will be the primary consideration in the site selection.
Further, the site will have to be suitable to the culture method or
system intended to be practiced. The important parameters to
be considered while selecting the site for mussel farming are
detailed below:
85
Water current
Mussel culture sites should not be in the vicinity of strong
currents as strong currents usually generate high turbidity and
high siltation rates. However, moderate currents (0.17-0.25m/s
at flood tide and 0.25-0.35m/s at ebb tide) are needed to provide
adequate food supply as well as to carry away the excessive buildup of pseudofaeces and silt in the culture area.
Water Depth
The depth of water column of a location determines the
type of culture method to be adopted. It can range from 1-15 m
at average mean low tide. The most important consideration
with regard to water depth is avoiding long exposure periods
during the extreme low-tides.
Salinity
Mussels grow well above 20psu, but the ideal salinity for
rearing is 27-35psu. Open coastal areas are usually fully saline
with minor seasonal variations. In estuarine areas, decrease in
salinity is usually the major and frequent problem, mainly caused
by the influx of freshwater from rivers or land runoff during the
rainy season. Therefore sites with a high inflow of fresh water
are not suitable for the farming of mussels. The culture season
for mussels is December to May, when the estuaries are in the
marine phase.
Turbidity
The presence of suspended particles above a certain level
disrupts the filtering activity of the bivalve, as the mussels remain
closed to avoid tissue damage and also due to gill clogging. In
addition, low primary productivity is often the case in sites of
high turbidity due to the reduced penetration of sunlight in the
water column. As a result poor growth results due to reduced
feeding time and limited food availability. It is found that water
containing a high suspended load of more than 400 mg/1 have
harmful effect on the grow-out of mussels.
86
Source of Seed
Mussel culture requires a proximity to spat or seed source,
which may affect site selection criteria. However, if it has to be
transported from elsewhere, it should be transported to the farm
site within a reasonable time and cost. Transportation itself is
not only costly, but usually negatively affects the quality of bivalve
seed due to stressful conditions. The mussel (P.viridis) seed can
remain without water for about 24 h and hence offers easy
transportability.
Pollution
The sedentary bivalve fauna are exposed to very high
probability of contamination and could act as vectors due to
their peculiar feeding habits and bioaccumulation potential.
Bivalves are known to accumulate trace metals and pollutants.
Waters with heavy industrial contamination such as trace metals
and organic compounds are therefore unsuitable for mussel
farming. Further, shellfish from contaminated areas are known
to accumulate bacteria and viruses that are pathogenic to human
beings. Regulations have been established in many parts of the
world that provide a system of classification of bivalve shellfish
growing/ harvesting areas, broadly based on water test results
(National Shellfish Sanitation Program, (NSSP) of USA and
Canada; Australian Shellfish Quality Assurance Program, ASQAP
of Australia) or tissue test results (Council Directive 91/492/
EEC of Europe) (Table 1&2). These classification systems assign
87
Criteria
Approved
MPN
MPN
<14/100ml <43/100 ml
Acceptable
no significant
pollution
sources
Restricted
MPN
MPN
Depuration Evidence
<88/100 ml <260/100 ml or relaying of marginal
pollution
Prohibited
None
No harvest allowed
Evidence
of gross
pollution
Geometric mean
Criteria
Category A
Direct human
consumption permitted.
Category B
Category C
88
Farming area
Open Sea farming
This is practiced in areas with a depth of 5-20m. The selected
area of culture should be free from strong wave action, less turbulent
and with high productivity. Long line and raft culture techniques
are ideal for open sea farming. Disadvantages of this type of farming
are poaching, unpredicted climatic changes and predation.
Estuarine farming
Compared to the open sea, the estuarine ecosystems are less
turbulent and shallow (<4m). Stake and rack culture (horizontal
and vertical) are ideal for estuarine conditions. Fluctuation in
salinity during monsoon season and pollution through domestic
and industrial waste are the main constraints in estuarine mussel
farming. On-bottom culture by relaying of mussel seed in pen
enclosures is also practiced.
Farming technique
On-bottom method
In areas where water depth is less than 1.5 m, mussels can be
farmed by sowing directly on the bottom substratum/ or seabed.
89
Bouchot culture
This method involves farming mussels in intertidal mud flats
on poles combining spat collection with ongrowing. Initially
poles are set in the intertidal seabed in rows to allow mussel spat
to settle and grow. Mussel spats settlement occurs directly on
these wooden poles or onto the horizontal coconut fibre ropes
strung onto the poles before settlement. When the spat grows
slightly bigger they are transferred to tubular nets and transferred
to "bouchot" placed in shallow waters in the same region. The
mussels attain marketable size on the poles.
90
Growth
The seed, which get attached to ropes, show faster growth in
the suspended water column. If the seed is not uniformly
91
Depuration
Depuration of the harvested mussels is necessary to increase
the quality of the mussel meat and to avoid the risk of consuming
92
Expenditure:
Table3.Tentative cost of Mussel Farming Rack Culture
Rack size 30m x 20m (600 sq. m) (1200 ropes of 1 m)
A. Initial Expenditure
I. Farming
Amount
17,600
93
13,750
37,500
2,650
5,000
8,500
12,000
8
9
10
11
Total
10,000
12,000
12,000
10,000
141,000
B. Recurring Cost
1
Cotton netting
(250mtr @ Rs.15/mtr)
2 Twine
3 Cost of seed (1800 kg @ Rs.6/kg)
4 Charge for seeding
(30 man days @Rs.200/head)
5 Hire charge of canoe
6 Charge for harvesting, de clumping
and cleaning
7 Labour for depuration
8 Plastic wares
9 Marketing
10 Miscellaneous
Total
3,750
150
10,800
6,000
2,500
10,000
3,000
4,000
5,000
3,800
49,000
190,000
94
Suggested reading:
Ashokan P.K. 2005. Site selection for bivalve culture.In Appukuttan K.K.
(Ed).Winter school Technical notes on Recent advances in mussel and
edible oyster farming and marine pearl production". p92-100.
Velayudhan T.S. 2005.Mussel farming methods & seed collection.
In Appukuttan K.K.(Ed). Winter school Technical notes on recent
advances in mussel and edible oyster farming and marine pearl
production. p122-126.
Mohamed K.S. 2005.Innovations in increase in mussel farming. In
Appukuttan K.K. (Ed).Winter school Technical notes on"Recent
advances in mussel and edible oyster farming and marine pearl
production". p127-123.
Kripa V. 2005.Bivalves and harmful algal blooms.In Appukuttan
K.K. (Ed).Winter school Technical notes on "Recent advances in mussel
and edible oyster farming and marine pearl production". p183-189
95
XI
REVIEW OF PROSPECTS
FOR LOBSTER FARMING
E.V.Radhakrishnan
96
97
land holding of legal size lobsters for weight gain and/or more
favourable (niche) marketing. In India there being no restriction
on fishing, large quantities of juveniles and undersize lobsters are
caught and marketed. Though there is good potential for fattening
to legal size, there is very little attempt. While some entrepreneurs
have shown interest, availability of healthy, quality seed is a major
constraint.
On growing involves holding undersized lobsters, which fetch
low price or not accepted legally for export, for short period until
they attain legal size .These lobsters could be held in tanks, ponds
or cages fed with natural or artificial feed. Growth could be further
enhanced remarkably through eyestalk ablation and by proper
feed and water management. Since live lobsters fetch high market
value, these can be marketed to targeted markets in Southeast
Asian countries.
Seed availability
Among the shallow water species occurring along the Indian
coast, Panulirus homarus, P. ornatus, P. polyphagus and Thenus
orientalis are the most promising species. These species can be
easily distinguished by the colour and morphological features.
The hatchery production of T. orientalis has already been
accomplished. The larval culture of the spiny lobster species
occurring in India is yet to be successful though some headway
has been made. Therefore farming or fattening of lobsters will
have to depend upon either the post larvae (puerulii) or the
undersized lobsters caught in artisanal gears. In India, lobsters
appear as by catch in trawls operated in Maharashtra, Gujarat
and Tamilnadu. The quantum of juveniles caught in trawls is
low. Artisanal gears such as trammel nets, gill nets and traps are
also used for fishing in inshore areas. Lobsters in gill nets and
especially more than 50% of catch in trammel nets are undersized
and cannot be legally exported. These are either illegally exported
or consumed internally. The secondary holding centres keep the
lobsters under highly stressed condition due to paucity of space
98
99
100
101
102
Indoor tanks
Two main systems are currently being used for fattening
lobsters: flow-through and recirculating. In flow through systems,
the water that is pumped into a tank is used only once. Water
flow is to be decided based on the stocking density and feeding
intensity. The incoming water is to be free of sediments and
should have water quality parameters required for lobster farming.
The water should be regularly monitored to avoid wide
fluctuations in environmental parameters. In recirculating
systems, the majority of the water is re-used after each pass
through the tanks, first being treated to remove waste products
before being returned to the tanks. Even though initial set up
costs may be higher, there is an increasing interest in the use of
recirculating systems. In recirculating systems also the main
limiting factor is dissolved oxygen: however, the unionized
ammonia concentration becomes increasingly important, and
is probably the next important limiting factor. Ammonia should
be removed from the system at a rate equal to the rate of
production to maintain safe concentration. All recirculating
systems remove waste solids, oxidize ammonia and nitrite, remove
carbon dioxide, and aerate the water before returning it to the
fattening system. Solid wastes can be removed by mechanical
filtration, ammonia and nitrite by biological filtration and carbon
dioxide by the provision of an air/water interface. The safe level
of ammonia for holding lobsters is <2 mgL-1. The flow rate
calculations must be adjusted according to the species held, size
of the animals, the rate of feeding and the holding temperature.
The required estimated flow rate in a tank holding 10000 kg of
500 g fed J. edwardsii lobsters at 13% C is 4500 L h-1. The water
management schedule and monitoring frequency of
environmental parameters is shown in Table 3.
103
Tank design
Raceways, rectangular, square or circular tanks can be used.
The most preferred are individual raceway tanks. Circular or
square tanks made of brick and cement or concrete are also good.
Square tanks will save space when compared to circular and are
also less expensive as they could be connected serially These tanks
will be difficult to clean and feed the lobsters. Raceways are easier
to maintain and with proper slope, the wastes can be easily
removed through the outlet pipe fixed at the end of the tank.
For complete removal of water, the standpipe can be lifted. Square
and circular tanks will have a central drainage system or a selfcleaning two way waste removal system by which both suspended
and settled wastes can be automatically flushed out of the tank.
The wastes can be concentrated towards the centre of the tank
by creating a vortex by the incoming water. This tank design is
used in flow through systems. For recirculating system the
wastewater flowing out of the tank is recirculated after removing
the waste products and will be a continuous process. Since lobsters
grow fast in subdued light, tank covers have to be provided to
avoid bright sunlight.
Stocking density
Undersized lobsters procured from secondary holding centres
transported to the fattening facility may be kept under quarantine
for 48 hours to relieve the lobsters from stress. The quarantine
facility should be away from grow out tanks. Healthy lobsters
may be stocked at 1.0-1.25 kg/m2 after segregating into different
size groups. The difference in weight between the lower and
upper size should not be more than 20 g. Hideouts provided in
the tank will help them to congregate around the shelter during
day and prevent them from continuously moving in the tank
spending lots of energy. Lobsters feed on variety of natural and
artificial feed making them suitable for farming. The natural
feed includes mussels, clam, squid, trash fish, and smaller crabs
and shrimp meat. Artificial includes shrimp pellets that are
104
106
107
Future prospects
All marine lobsters are highly considered as fine table food
and thus are in high demand. Most wild fisheries are
overexploited, with many stocks having already collapsed or catch
rates closely regulated to sustain the wild fishery. For these reasons,
lobsters fetch high prices. The highest price is paid for live
product, chilled or frozen products bring much lower prices.
Aquaculture offers the only prospects by which lobster supplies
can realistically and sustainably be increased. Considerable export
potential exists for live product to Southeast Asian markets.
Packing and transport conditions for live shipment of lobsters
are well developed and would not be a problem. Development
of a successful export market would require both continuity of
supply and a reasonable volume of production. However, the
greatest concern is whether aquaculture production would be
sustainable if recruiting seed was taken in large quantities for
aquaculture.Attempts in 1970s and in late 1990s to establish
large-scale intensive aquaculture of spiny lobsters in the
Philippines collap-sed within a few years of establishment when
seed supplies became insufficient to support the venture. In India
the resource is limited to certain pockets along the coast and
lobster landing is drastically declining in all the centres due to
indiscriminate fishing. Therefore, before contemplating
aquaculture, research is warranted to better determine the stock
structures of spiny lobsters and to estimate recruitment patterns
and survival rates. Such research would enable responsible fishery
management policies to be put in place to ensure sustainability
of the wild fishery stocks. Low intensity aquaculture of spiny
108
Tolerance limits
Temperature
DO (% saturation)
12 to 31C (25-30C)
Minimum 70%Preferably
above 80%
30-38
<2
<5
100
7.8 to 8.4
100-200
Salinity (ppt)
Ammonia (mg L-1)
Nitrite (mg L-1)
Nitrate (mg L-1)
PH
Hardness (ppm)
52.3
45.9
39.9
35.7
30.1
27.8
23.8
25.0
21.8
24.4
109
40
47
53
65
74
83
84
79
91
112
Schedule
Equipment
Temperature
Salinity
Salinity
refractometer
pH
pH meter
Oxygen
Oxygen probe
Measuring kits
References:
Kitaka, J. 1997. Culture of larval spiny lobsters: a review of work done
in northern Japan. Mar. Freshwater Res., 48, 923-930.
Lellis, W. 1991. Spiny lobster: A mariculture candidate for the Caribbean?
World Aquaculture, 22(1): 60-63.
Lellis, W.A. and J.A. Russel. 1990. Effect of temperature on survival,
growth and feed intake of postlarval lobsters, Panulirus argus.
Aquaqculture, 90:1-9.
Mace, P.M. 1997. Developing and sustaining world fisheries resources:
the state of the science and management. In Developing and sustaining
World Fisheries Resources: the State of the Science and Management.
Second World Fisheries Congress, Brisbane 1996: (Eds. D.A. Hancock,
D.C. Smith, A. Grant and J.P. Beumer) pp. 1-20 (CSIRO Publishing;
Melbourne).
110
Philipps, B.F. and L.H. Evans, 1997. Aquaculture and stock enhancement
of lobsters: report from a workshop. Mar. freshwater Res. 48(8):
899-902.
Radhakrishnan, E.V. 2004. Prospects for grow out of the spiny lobster,
Panulirus homarus in indoor farming system. In: program and Abstracts,
7th International Conference and workshop on Lobster Biology and
Management, 8-13 February, Hobart, Tasmania.
Radhakrishnan, E.V. and M.Vijayakumaran. 1984. Effect of eyestalk
ablation in spiny lobster Panulirus homarus (Linnaeus). 1. On moulting
and growth. Indian F. Fish., 31(1): 130-147.
Sarvaiya, R.T. 1991. Successful spiny lobster culture in Gujarat. Fishing
Chimes, 10 (11): 30-31.
111
XII
Biomass
Biomass can refer to species biomass, which is the mass of
one or more species, or to community biomass, which is the
mass of all species in the community. The mass can be expressed
as the average mass per unit area, or as the total mass in the
community. How biomass is measured depends on why it is
being measured.
Biomass = Mean weight x Number of fishes
Weight Gain (WG) = Initial body weight - Final body
weight of fish
114
115
Feed Efficiency
A figure used to represent the efficiency of food use. The
inverse of the feed conversion ratio e.g. a feed conversion ratio
of 1 : 1.5 becomes a feed efficiency of 0.66 (1 / 1.5).
Feed Rate
The amount of feed given to the fish, over a specified period
of time . The most common way of expressing this is as percentage
of the animal body weight per day. For example a 1000 gram
fish, being fed 20g of feed per day would be on a 2% feed rate
[(20 / 1000 ) x 100)].
Energy Assimilation
The food consumption of fishes can be summarized in the
following equation:C=P+R+F+U
where, C = food consumption in energy terms (Joules); P =
energy used for tissue growth (including fat deposition, egg and
sperm development); R = energy used for work (including body
maintenance, digestion, activity); F and U = energy losses in
faeces and urine respectively. The amount of useful energy
available to the animal, or assimilation (A) as it is generally
termed, can be derived from A = C - (F + U) = P + R. Assimilation
is often quantified in terms of assimilation efficiency.
Carrying capacity
A major consideration in the site selection process should be
the carrying capacity of the site which indicates the maximum
level of production that a site might be expected to sustain.
Intensive cage fish farming results in the production of wastes
which can stimulate productivity and alter the abiotic and biotic
characteristics of the water body, whilst less intensive methods
can result in over cropping of algae and a fall in productivity.
Hence profitability or even viability may be seriously affected.
Therefore it is extremely important for all concerned with cage
116
Condition Factor
An easily measured index of growth is the length-weight
relationship, often referred to as condition factor (C). C is the
ratio of fish weight to the length cubed. Condition factor, one
of the most important feeding and growth criteria. Since C
may vary between species, strains, diet and feeding levels, water
quality and hatchery management, it should be calculated for
each hatchery. C is calculated by weighing a sample of 50-100
fish together. After the average weight and the average length
are measured, values are used in the formula C=W/L3. A high
condition factor would indicate a well-fed fish, while a low
condition factor may indicate a poorly fed fish of the same length.
117
XIII
ENVIRONMENTAL
MONITORING IN
SEA CAGE CULTURE
Jayasree Loka, S.M. Sonali,
L.S. Korabu and K.K. Philipose
118
120
Monitoring methodology
There are several considerations to be taken into account when
deciding on monitoring methodology. These include:
(i) frequency of sampling;
(ii) position of sampling stations;
(iii) method of sampling water or sediments; and
(iv) method of analysis of the samples taken to measure the
determinants.
These factors will be different with type of culture and method
of waste discharge. Again, there is no fixed method of deciding on
these factors as this is dependent on the purpose of the monitoring
study. Sample strategies usually attempt to maximise data collection
per expended effort, which normally entails the use of transects
aligned with the direction of principle current flow rather than a
less efficient but more statistically rigorous random sample or grid
approach. Samples along these transects may be taken using water
samplers such as the Van Dorn and sediment samplers like remotely
operated grabs, dredges, trawls or corers or diver operated
techniques such as photography, video, corers or REMOT systems.
Grabs and coring techniques can be used to take quantitative
samples which give accurate and easily comparable temporal and
spatial data for physical, chemical and biological analysis (Fig.5).
Photography and video methods are qualitative or semiquantitative but are good visual record of change.
Recently, with the advent of advanced computer based
electronic methods, surveys can be undertaken using
sophisticated ship based technology. Such a method is side scan
sonar which has been used, with varying success, to characterise
sediment types throughout bays containing fish farms
(MacDougall and Black, 1999) and for mapping biotopes in
coastal regions. Initial findings show that these techniques need
further work but they offer promise for the future where surveys
will be able to study large areas of seabed quickly and accurately.
121
122
Source:
FAO 2009 Environmental Impact Assessment and Monitoring in
Aquaculture.
MAFRI Report No. 46. (2002) Gavine,F. M. and Mc Kinnon, L. J.
2002. Environmental Monitoring of Marine Aquaculture in Victorian
Coastal Waters: A Review of Appropriate Methods. Technical Report
No.46. Marine and Freshwater Resources Institute, Victoria
124
XIV
Iridovirus infections:
Iridoviruses, causative agents of serious systemic diseases have
been identified from more than 20 fish species in the recent
years. Most fish iridoviruses are members either of the genera
Lymphocystis virus or of the genera Ranavirus. Iridoviruses in
genera Lymphocystis virus cause the development of cluster of
extremely hypertrophied fibroblasts or osteoblasts called
lymphocystis cells, while viruses in genera Ranavirus may lead
to systemic disease in infected animals and are associated with
high morbidity and mortality. A typical iridovirus has icosahedral
symmetry and measures 130300 nm in diameter. Characterization of iridoviruses has been hindered by the difficulty in
isolating and propagating them in tissue cultures.
The most dramatic change in all affected fish is the presence of
basophilic, hypertrophied cells, often in large numbers, in various
organs. These cells, with a pale foamy or intensely basophilic
granular appearance, were often observed in the splenic
parenchyma and capsule, in the renal glomerulus and interstitium,
127
Lymphocystis:
Lymphocystis disease (LCD), one of the common infectious
diseases affecting marine fish cultures, was discovered in 1874.
Distribution has been reported worldwide such as Spain, Korea,
Japan and China. The causative agent of LCD is lymphocystis
disease virus (LCDV) which is a large virus in the genus
Lymphocystis virus of the family Iridoviridae. LCDV is an
icosahedral symmetry virus, approximately 200-300 nm in
diameter, and contains single linear double stranded DNA. LCD
is characterized by the external appearance of nodules, either
singly or in groups, on skin, fins, or tail of the affected fish.
Although, LCD is not a fatal disease, the external appearance
might cause a significant economic loss. The principle mode of
transmission of LCD is horizontally by direct contact and external
trauma. Other factors such as water contamination and stress
condition caused by high stocking density, nutrition deficiencies,
low dissolved oxygen, suboptimal water quality, or human
manipulation may increase the appearance of LCD symptoms.
A recent study reported that Artemia sp. might act as a reservoir
host of this disease (Cano et al., 2009).
The affected fish reveals multifocal to diffuse white, firm,
papilloma-like nodulesscattered on the skin, fins, eyes and mouth.
128
Vibriosis:
Vibriosis is a disease characterized by haemorrhagic septicaemia
and caused by various species of Vibrio. It occurs in cultured
and wild marine fish in salt or brackish water, particularly in
shallow waters during late summer. Within the Vibrionaceae,
the species causing the most economically serious diseases in
129
130
Streptococcal infection:
Streptococcal infection of fish is considered as re-emerging
disease affecting a variety of wild and cultured fish throughout
the world. Five different species are considered to be of
significance as fish pathogens: Lactococcus garvieae, L. piscium,
Streptococcus iniae, S. agalactiae, S. parauberis and Vagococcus
salmoninarum. Therefore, streptococcosis of fish should be regarded
as a complex of similar diseases caused by different genera and
species capable of inducing a central nervous damage characterised
by suppurative exophthalmia and meningoencephalitis. Warm
water streptococcosis typically involves L. garvieae, S. iniae, S.
agalactiae and S. parauberis. It is important to report that the
etiological agents of warm water streptococcosis are considered
also as potential zoonotic agents capable to cause disease in humans.
Among these fish streptococci, L. garvieae, S. iniae and S. parauberis
can be regarded as the main etiological agents causing diseases in
marine aquaculture. S. iniae was isolated from marine fish including
European and Asian seabass in Australia. Streptococcus infection
can be diagnosed by biochemical tests.
infected lobsters, other than weakness or lethargy and a spreadeagle posture which are apparent in later stages of the disease, and
which are not pathognomonic for gaffkemia. Lobsters rapidly
become anorexic after infection. The bacteria multiply rapidly in
the hepatopancreas and then in the heart. The pathogen multiplies
in the hemolymph much later in the infection. Pink discoloration
of the ventral abdomen and hemolymph will develop. Death results
from metabolic incapacity resulting from dysfunction of the
hepatopancreas. Additionally, the clotting mechanism is impaired,
and it is associated with marked hemocytopenia. Infected lobsters
can become exsanguinated, especially in end-stage disease.
132
Cryptocaryon disease
Cryptocaryon disease in the fish, also called the Marine white
spot, is caused by the ciliated protozoan parasite. This disease
spreads if the quality of water is not good. If the pH level of the
water is reduced then, it might lead to the Cryptocaryon outbreak.
One of the signs of Cryptocaryon infection is lethargy in the
fish and it might also rub itself against all the objects found in
the aquarium. This type of behaviour is obvious if there is
Cryptocaryon infection. We can notice white spots (2 mm) on
the body and fins. The white spot first appears in the pectoral
fins and then spread to the other parts. The gill is one part that
has many of these organisms. The white spots spread to the entire
body and it might also lead to hemorrhage later. During the
advanced stages of this infection the eyes of the fishes would be
clouded which might cause blindness and lead to other diseases
like fungal infections which adds to the already existing problem.
Since Cryptocaryon is a parasite it will need a host for its
development. During the initial stage the Cryptocaryon will be
free swimming and it will try to find a host for its development.
134
Once it finds a host it will penetrate the skin of the host i.e. the
fish. The free swimming stage of Cryptocaryon is called tomite
and the parasitic stage is called trophont. It feeds on the tissues of
the fish and grows. The size of the parasite double every single day
and it is visible to the naked eye after two days. After about 4 days
a cyst is formed which will give rise to another 100 to 300 tomites.
It is only about 5 to 10 percent of the tomites succeeds in finding
another host for its development. Every week you can find the
population of Cryptocaryon increases ten times. Due to this rapid
increase the effect of the infection will also increase dramatically.
Acting at the earlier stage of detection of this parasite will be
helpful in eradicating this infection altogether. Dangerous levels
of the infections are reached within 12 days of the infection. So
it is better to start the treatment at the earlier stage itself to remove
those infections.
In the treatment of Cryptocaryon, copper based mediations are
useful. The dosage of copper used should be appropriate so that it
does not affect the fish. The treatment using copper should be done
for several times daily. Even after removal of the parasite the treatment
has to be continued for about a week so that you remove all the
latent tomonts too. This is to ensure that the fish is not affected
again. Fresh water bath will be tolerated by the fish for about half an
hour only. However we have to maintain the pH of this water too.
Source:
Alicia E. Toranzo,A.E., Magarinos, B., Romalde, J.L. (2005) A review of
the main bacterial fish diseases in mariculture systems. Aquaculture, 246:
3761.
Muroga, K. (2001) Viral and bacterial diseases of marine fish and shellfish
in Japanese hatcheries. Aquaculture, 202: 2344.
Huguenin, E. (1997) The design, operations and economics of cage culture
systems. Aquacultural Engineering 16: 167-203.
135
Xiao-Wen Wang, X-W., Ao, J.Q., Li, Q.G., Chen, X.H. (2006)
Quantitative detection of a marine fish iridovirus isolated from large yellow
croaker, Pseudosciaena crocea, using a molecular beacon. Journal of
Virological Methods 133: 7681.
Gibson-Kueh, S., P. Netto, P., Ngoh-Lim, G.H., Chang, S.F., Ho,L.L.,Qin,
Q.W., Chua, F.H.C,a,. Ng, M.L., Ferguson, H.W. (2003) The Pathology
of Systemic Iridoviral Disease in Fish. J. Comp. Path. 129: 111119.
Cawthorn, R.J. (2011) Diseases of American lobsters (Homarus
americanus): A review. J. Invertebr. Pathol 106 (2011) 7178.
Cano, I., Alonso, M.C, Garcia-Rosado, E., Rodriguez Saint-Jean, S., Castro,
D., Borrego, J.J. (2006) Detection of lymphocystis disease virus (LCDV)
in asymptomatic cultured gilt-head seabream (Sparus aurata, L.) using an
immunoblot technique. Veterinary Microbiology 113: 137141.
Pirarat, N., Pratakpiriya,W., Jongnimitpaiboon, K., Sajjawiriyakul, K.,
Rodkhum, C., Chansue, N. (2011) Lymphocystis disease in cultured false
clown anemonefish (Amphiprion ocellaris) Aquaculture. doi: 10.1016/
j.aquaculture.2011.01.014
136
XV
CAGE FARMING OF
FINFISHES IN ESTUARIES
A.P. Dineshbabu
137
138
139
140
Demonstration experiments by
Central Marine Fisheries Research Institute
Central Marine Fisheries Research Institute is one of the pioneer
Research Centres in transferring mariculture technologies in the
State of Karnataka. The participatory approach gave exposure to
the local fishers on the finfish rearing aspects besides creating
awareness on this lucrative farming technique. Encouraged by this
success many fishermen group evinced interest in rearing finfish
in suitable farming areas near their backyard.
Karnataka state has 8,000 hectares of unpolluted brackish waters
and estuarine areas, which are highly suitable for capture based
aquaculture. The local fishermen use dragnets, castnets and gillnets
in estuarine and coastal waters, which harvest juveniles of
commercially important cultivable finfishes. These juveniles fishes
though live at harvest are invariably discarded due to low market
demand. The juvenile of commercially important species such as
redsnapper, pearlspot, mullets, seabass etc are available in the
inshore waters of Karnataka for CBA.
141
142
Husbandry:
The red snapper and pearlspot fingerlings were continuously
stocked by fishermen and the fishermen community was engaged
in the cage setting, cage cleaning, feed sourcing, feed preparation
and feeding. Feeding was done with locally available trash fish
and also fish waste from fish processing areas/plants.
Mean size
350 70 mm
(115-205 mm)
510 50 mm
Seabass
(310-620 mm)
Harvest
Mean weight Numbers wt.(kg)
755 415g
(105-1914g) 105
150
96 35g
(37-222g)
988
150
1819 540g
(262-3049g) 255
450
Total
1348
27,000
22,500
99,000
750 1,48,500
375
143
Amount
(Rs)
74,250
144