Volume 6, Issue 7, July – 2021 International Journal of Innovative Science and Research Technology

ISSN No:-2456-2165

Growth, Survival and Biomass of Etroplus suratensis

in Shallow Water Cages Installed at Gopalpur Creek,
Bay of Bengal, India
N. K. Sial, G.C. Kund, D. Satapathy
Post-Graduate Department of Aquaculture,
College of Fisheries
Odisha University of Agriculture & Technology (OUAT),
Berhampur-760007, Odisha, India

Abstract:- With an intention to integrate artisanal level shrimps and crabs in small cages suitable for such shallow
of capture based aquaculture with the sustainable waterbody.
management practices of small scale fisheries an attempt
has been made through this study to collect juveniles and The selection of species needs to be based on their
sub adults of Pearl spot Etroplus suratensis from abundance, duration and above all the suitability of aquatic
Gopalpur creek and to stock in small cages installed in system for its growth and survival. On the contrary the
the same waterbody to observe its growth so as to adoption of CBA under small scale fisheries in shallow
develop a package of practices for local fishers as an waterbody without appropriate measures may increase the
option of additional income. Three sets of cages with risk of spreading pathogens and water pollution. Authors
three replicas of each one were fixed and sub adults of [1], [4], [.7], [9], [12], reported on various aspects i.e.
Etroplus suratensis were stocked at the rate of 15, 20 and raising fish in small cages in estuaries, adoption of cage
25 nos per m2 for a period of 150 days. During the period culture, supplementary feeding and growth rates,
of experiment temperature fluctuated from 24.6- 31.8oC, advantages, dis-advantages and risk of such practices in
water pH from 8.1- 8.5, Water transparency from 14.2 – Indian context whereas [2], [11], [13], reported on
32.9 cm, Dissolved oxygen from 5.0- 6.9 ppm, and water production aspects. [3], [5] and [8] reported on failures of
salinity from 5.3- 21.3 ppt in the cage installation site. management aspects and suggested to make necessary
The daily growth rate (DGR) marked a fluctuation from adjustments accommodating the biological, agricultural and
0.347 to 0.593 g/day while the specific growth rate (SGR) socio-economic realities.
fluctuated from 0.48 to 0.75%. More production was
obtained from cages stocked with more stocking density. II. MATERIALS & METHODS

Keywords:- Gopalpur Creek, Etroplus Suratensis, Shallow A. Study Area

Water Cage, Daily Growth Rate, Specific Growth Rate, Gopalpur Creek lies between 19o 16’ 22” Nand 19 o
Survival and Biomass. 15’ 39” N Latitude and between 84 o 54’ 0.6” E and 84o
55’15” E Longitude is a typical brackish water ecosystem
I. INTRODUCTION spreading over 8-10 km2. It is influenced by agriculture run-
off from one side and tidal ingress from other side through
The capture based aquaculture is a kind of farming its mouth located in East side. Usually, the mouth, the inlet
technology where fish seeds/ juveniles/sub adults are caught of the creek varies from 25 to 40 meter in monsoon with a
in its early stages from a definite waterbody and is grown to depth of 3 to 4 meters separating two sand dunes. However,
its adult size or marketable size in captive conditions. It this inlet gradually gets filled up in sand due to littoral
generates more profits; ensure employment and marketing. drifting of water current prevalent in Gopalpur bay and
It has the potential to generate profits when compared to becomes 25-30 meters in width with 0.5 to 1.0mt in depth
other aquaculture activities to a greater extent leading to during summer months. Heavy influx of sea water continues
socio economic development of a region. It would be to take place through the inlet into the creek throughout the
appropriate to integrate artisanal level of capture based year in each high tide and discharge into the sea in
aquaculture or indigenous methods of culture with the corresponding low tide. Therefore, varied forms of marine
sustainable management practices in tune with small scale organisms enter to the creek including fish and shrimp
fisheries (SSF) in India. Small-scale fishing dominates in juveniles and larval forms. Besides, the sea water and fresh
many countries including India. It needs low investment, water discharge develop a brackish water environment and
indigenous gears, indigenous technical knowledge (ITK) serves as estuarine habitat for fish, shrimp, crabs and oysters
simple skill and an easy approach. In this regard, the shallow and bivalves etc.
waterbody like estuaries, creeks and tidal lagoons etc. offer
excellent scope for practice, particularly growing fish,

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Volume 6, Issue 7, July – 2021 International Journal of Innovative Science and Research Technology
ISSN No:-2456-2165
During monsoon often entry of fish and shrimp larvae weight gain and the result was expressed in g. The Specific
takes into the creek water. Many of them goes back to the growth rate was estimated following standard formula =
sea and a few makes its habitat in the creek which serves as (100 x (LN final weight – LN initial weight) /days)) taking a
the source of capture fisheries to nearly 700 fisher families sample size of 25% from each cage. Critical water quality
inhabiting in the bank of creek i.e. Gopalpur fishermen parameters like temperature and dissolved oxygen (DO)
village and Haripur village. The creek is leased out to the were observed on daily basis using temperature probe and
fishermen society on annual basis for the purpose of capture digital DO meter while routine parameters i.e. transparency,
fisheries. The excess runoff of freshwater during monsoon pH, and salinity were ascertained at fortnight intervals
and brings down the salinity and provides ample of following sechi disc method and using pH meter and
opportunity for fresh water fishes. Gradually, the water salinometer respectively. The repair of cages and cleaning
converts to brackish water soon after monsoon ends and and replacement of nets etc., were carried out as and when
further increases to become saline later on. Subsequently, necessary.
owing to restricted ingress of seawater and excess of
evaporation makes the system hypersaline. III. RESULTS AND DISCUSSION

B. Species Selection Out of three treatment cages of set I, the first cage with
Realizing the need of promotion of artisanal fisheries a stocking density of 15nos/m3, where fish juveniles of size
in Gopalpur creek, Odisha by way of enhancing fish below 45mm/42g were stocked recorded its body weight
production, it was thought of to retain fish and shrimp seeds/ gain of 47g, 58g,75g, 100g and 130g during 30 days, 60
juveniles available during monsoon which otherwise go days, 90days, 120days and 150 days of culture while in the
back to the sea, and to grow them in small shallow water 2nd cage the body weight enhanced from 45g to 48g, 55g,
cages as a source of additional income. An attempt was 70g, 105g and 125g and in third cage fish grew from initial
made to observe the growth of pearl spot fish Etroplus sp in 48g upto 54g, 65g, 78g, 115g and 137g in 30th, 60th ,90th,
cages, so that a definite programmer can be developed for 120th and 150th days of culture. The daily growth rate
wise use of its resources. Pearl spot, is indigenous to Indian (DGR) varied 0.59g, 0.53g and 0.59 with a mean of 0.571 ±
continent and Srilanka. It inhabits in estuarine conditions 0.03 g./day and specific growth rate (SGR) fluctuated from
and has high capacity for acclimatization to freshwaters at 0.681% to 0.753% with a mean of 0.711 ± 0.03 %.
all size groups. Filamentous algae and detritus constitute the Similarly, in the 2nd set of experimental cages with a
major food for the fish in its habitat. The species having stocking density of 20 no’s/m3 fishes stocked between 45-
browsing / ‘scraping’ behavior keep the cages free from 55mm/42-48g recorded maximum growth up to 122 g in 4th
fouling and mesh clogging algae. cage followed by 120g in 5th cage and 115g in 6th cage
indicating mean DGR of 0.493 ± 0.04 g/day and SGR of
C. Fabrication and installation& stocking and monitoring 0.649 ± 0.06 % while the 3rd set of cages of stocking
Three sets of experimental cages (each set having three density of 25 no’s/m3 where fishes between 45-55mm/ 42-
each) were fixed closure to the inlet so as to take the 48g recorded maximum growth up to 112g in 7th cage
advantage of water flow during high and low tide. Cages of followed by 110g in 8th cage and 100g in 9th cage resulting
rectangular size 2.0 m x 1.0 m x 1.2 m made of locally mean DGR of 0.415 ± 0.06 g/day and SGR of 0.579 ±
available bamboo splits with 15 mm gaps between bamboo 0.08 %. Statistical analysis (ANOVA) indicated no
splits were fabricated by the local fishermen. Nylon significant variation of growth of fish within cages and
mosquito nets of 0.5 mm mesh size were tied as an inner significant variation of growth within months. Added,
layer to protect fish from abrasion and avoid loss of feed survival rate of fishes was relatively high (87-93%) in 1st set
pellets. The cages were kept in fixed position by towing it in followed by 2nd and 3rd set of cages (80-87%). But
prefixed bamboo poles interlocking in a line in such a way maximum biomass was obtained from 7th cage (5.00kg)
that the width of cage faces water current so that water can followed by 4th& 8th cage (4.600kg each), 9th cage (4.400
pass through all the three cages thus making it very efficient kg), 5th& 6th cage (4.00 kg each), 3rd cage (3.800kg), 1st cage
in water exchange. Bamboo barricade was provided for each (3.600 kg) and 2nd cage (3.200 kg) indicating higher biomass
location to protect the cage from floating weeds and in cages having more stocking density in spite of relatively
turbulence due to tidal force. The outer opening of cage is low survival rate.
provided with a cover made of same bamboo split wrapped
with mosquito cloth to protect against sunlight and birds. Experiments on cage culture in India indicated yield
Seeds/ juveniles of pearl spots, Etroplus suratensis, of size rates range from of 0.7 to 1.3 kg/m3/month [7] while, [9]
between 45-55 mm / 42-48 gm collected from the same reported total fish production of 16.03 kg/m3/year. Author
waterbody and were stocked at three different densities of [4] recorded an average fish production of 26.76± 9.308kg
15, 20 and 25 nos./ m2 in three different sets of cages. The (range 17.80- 44.40) kg/m3 in 205.3 ± 60.9 days of culture
stocked fishes were fed twice a day with dry pellets at the with a record of 0.50-0.90 g growth per day at a survival rate
rate of feeding were adjusted according to biomass 5-7% varying between 45 and 100%. The fish attained maximum
adjusting to the biomass of the cage. size of 350-480 g at harvest (average size of 163.76 ±
40.214g) at a specific growth rate ranged from 0.27 to
The weight gain of fish was determined by subtracting 0.76% leading to a situation of more the production from
initial weight from final weight. This weight gain is divided higher the stocking density (230 no’s/ m3).
by number of culture days to ascertain the average daily

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Volume 6, Issue 7, July – 2021 International Journal of Innovative Science and Research Technology
ISSN No:-2456-2165
Growth performance of pearl spots (E. suratensis) to dissolved oxygen it marked non-significant variation within
an extent of 0.593 g/day at Gopalpur creek throughout this months and sites. All the water parameters were suitable for
study appears less than the results obtained by [4] from growth of fish during the period of experiments.
Venbenad lake of Kerala but certainly better considering its
natural growth in open waters of Gopalpur creek. The Usually, unused feeds settle below the cages if not
growth rate of Pearl spot is comparatively much slow than dispersed through water current and such accumulation lead
many estuarine fishes, hardly growing to 120-130 g. The to decomposition and depletion of oxygen level. On the
attainment of 137g in 150 days in shallow water system event of prolonged situation, biological oxygen demand
encourages its possibilities of cages culture. Fish production (BOD) increases. Author [15] reported very low levels near
increases with increase of stocking size limiting to its cages. However, high oxygen levels between5.2 ppm to 6.9
maximum growth phase and similarly with stocking density ppm observed at the cage installation site in the present
considering its carrying capacity. But in the present study indicative of stress free situation. Added the water
investigation such kind of result was not recorded. It could circulation through cages compensated the dissolved oxygen
be due to the fact of stocking of oversize fish in cages. This concentration of water in fish cages. So it confirms good
implies that higher stocking density would have fetched exchange of water between cage and open water in the
more production. The mortality rates were low when present study and minimal clogging and fouling of nets and
stocking size and stocking density was more without much cages. The low transparency (below 20 cm) recorded in the
fluctuation. The observed biomass 2.50 kg/m3 of pearl spot months of July, August and September was the effect of
under cage culture is satisfactory for the study. Higher sediment transport because of littoral drift phenomenon
stocking density and frequent feeding results, increased prevalent in Gopalpur bay coupled with mixing of silt laden
production in cage fish farming particularly for carnivorous rain water flow from the adjacent catchment areas. Added,
fed fishes but not for pearl sopt with browsing feeding frequent rains and very low levels of salinity often
habits. The results also confirm that pearl spot adapts well in associated with the risk of disease outbreak in caged fishes.
low to moderate volume cages suitable for shallow In the present study neither any indication of disease nor its
waterbody which could be due to its schooling behavior. occurrence was noticed.
Therefore, higher stocking stocking density to an extent of 4
to 5 time would be possible. IV. CONCLUSION

The net cages stocked with pearl spots were free from Based on the growth performance of Pearl Spot E.
clogging of algae and fouling of biofilms due to its algal suratenis as recorded in the present experiment, it is
browsing behavior and algal grazing tendency mostly on concluded that there is a possibility to undertake shallow
filamentous algae and detritus as evidenced from the water cage culture in the Goplpur creek by the local
findings of [6], [10] and [16]. The bamboo sticks and its fishermen community either at individual or family or
supported pieces acted as good substrates for the growth of through fishermen’s’ cooperative society. However,
filamentous algae and bio-film that served as an additional considering evidences of failures in cage farming
source of natural food for the fish. management practices in spite of inclusion of small-scale
fish farming in Africa in the late 1950s and early 1960s as a
The values of physic-chemical parameters of water in means of improving the quality of life for poor farmers as
the cages like temperature, dissolved oxygen, transparency reported by (Kalinga, 1991) adequate precautions need to be
and pH were well within tolerable limits of fish. However, taken and suitable practice of packages need to be followed
in set I cages (C-1, C-2 & C-3) where fishes were stocked at before adopting such technologies in this waterbody.
a density of 15 no’s/m3 water temperature fluctuated from
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( 23.1 ± 9.06 cm), water pH from 8.2- 8.5 ( 8.4 ± 0.10) and its role in fishery enhancement in China”, FAO
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temperature and water salinity and non-significant variation Vol. 22(2), 2009 pp. 839-847
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[5]. K.L. Cichrame, “Reconciling sustainability, economic Li and Jack Mathias), Elsevier, Amsterdam, 1994, pp.
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TABLE 1. Water quality in the cage sites during the period of cage culture practice in Gopalpur creek, East coast of India.
1st 90
Water parameters day 30 days 60 days days 120 days 150 days
3
Stocking density (15nos/m ) Jul Aug Sep Oct Nov Dec
Temperature (oC) 30.0 31.1 30.8 29.6 27.9 24.6
Dissolved Oxygen(DO) 5.2 5.6 5.6 5.7 6.8 6.9
Transparency (cm) 17.4 14.2 20.8 26.3 29.5 32.9
Water pH 8.1 8.2 8.4 8.5 8.4 8.3
Salinity (ppt) 12.3 10.5 17.4 19.3 20.7 21.3
Stocking density (20 nos/m3)
Temperature (oC) 30.6 31.8 31.2 29.2 26.8 25.2
Dissolved Oxygen(DO) 5.0 5.5 6.1 5.4 5.2 5.9
Transparency (cm) 16.2 15.4 17.3 21.2 37.5 30.8
Water pH 8.3 8.2 8.4 8.5 8.4 8.3
Salinity (ppt) 12.5 11.3 16.4 17.8 20.2 20.8
Stocking density (25 nos/ m3)
Temperature (oC) 30.8 31.5 31.2 29.7 27.4 25.3
Dissolved Oxygen(DO) 5.2 6.1 5.9 5.3 6.4 6.5
Transparency (cm) 15.7 16.3 16.8 20.5 31.7 30.8
Water pH 8.3 8.2 8.4 8.5 8.4 8.3
Salinity (ppt) 5.3 9.4 13.4 15.6 19.8 21.2

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Volume 6, Issue 7, July – 2021 International Journal of Innovative Science and Research Technology
ISSN No:-2456-2165
TABLE.2. Growth, survival and biomass of E. suratensis in experimental cages during 150 days of culture at Gopalpur creek,
East cosat of India
Site –I Site-II Site III
Features
(set-I) (set-II) (set-III)
C-1 C-2 C3 C-4 C-5 C6 C-7 C-8 C-9
3
Cage size (m ) 2.4 2.4 2.4 2.4 2.4 2.4 2.4 2.4 2.4
Cage stocking volume 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0
Stocking density (nos/ m3) 15 15 15 20 20 20 25 25 25
Days of culture (DOC) 150 150 150 150 150 150 150 150 150
Mean stocking size
Weight (g) 42 45 48 42 45 48 42 45 48
Length (mm) 45 50 55 45 50 55 45 50 55
Max. size at harvest
Weight (g) 130 125 137 122 120 115 112 115 100
Length (mm) 125 112 130 128 110 105 110 120 105
Survival (%) 93 87 93 87 80 87 87 80 87
Total Biomass (kg/m3) 1.8 1.6 1.9 2.3 2.0 2.0 2.5 2.3 2.2
DGR ( g. fish/day) 0.586 0.533 0.593 0.533 0.500 0.446 0.467 0.433 0.347
SGR( %) 0.753 0.681 0.699 0.710 0.654 0.582 0.654 0.595 0.489

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