313
ment of productivity in polyculture. Species combination and their compatibility
are of great concern to achieve higher productivity and profitability in polyculture
but information in this context is scanty.
In this context a project initiated by Dr. Subhra Bikash Bhattacharyya and Dr.
Asish Mondal during 2013 to 2015 aimed to evaluate different species combinations in brackishwater polyculture to assess their compatibility thereby increasing
production and profitability. Different species combinations were tested involving
commonly cultivated tiger shrimp (Penaeus monodon Fabricius, 1798) and three
varieties of fishes namely parsia (Liza parsia Hamilton, 1822), grey mullet (Mugil
cephalus Linnaeus, 1758) and milkfish (Chanos chanos Forsskål, 1775).
Consequences of intensification with increased stocking density of tiger shrimp
being the highest revenue earner and addition of a local high value fish, tade mullet
(Liza tade, Forsskål, 1775) were also tested in the later phase. Main aim was to
achieve better production and profitability in a sustainable manner.
The study was carried out at Manmathapur-Mundapara village (21.879493–
21.894148°N, 88.263668–88.276199°E), Kakdwip, South 24 Parganas, West
Bengal, India at the bank of Kalnagini River. All species were reared together as
control and one fish species was eliminated for each treatment in triplicate ponds
(300–500 m
2
) for both the crops. Tiger shrimp (Penaeus monodon Fabricius, 1798),
parsia (Liza parsia Hamilton, 1822), grey mullet (Mugil cephalus Linnaeus, 1758)
and milkfish (Chanos chanos Forsskål, 1775) were polycultured for 240 days at
respective stocking densities of 20,000, 5000, 5000 and 2500 numbers ha
−1
during
April to December, 2013. The species combinations were evaluated again in 300 days
rearing with increased stocking density of 40,000, 10,000 and 5000 numbers ha
−1
for
tiger shrimp, parsia and milkfish, respectively and added with tade mullet (Liza tade,
Forsskål, 1775) at stocking density of 5000 numbers ha
−1
during August, 2014 to
June, 2015 where tiger shrimp was harvested after 150 days. Growth, production,
economic, water quality and feeding ecology parameters were evaluated.
Significantly (p < 0.05) higher harvest weights and condition factors with isometric or positive allometric growths of all fin fish species were observed in treatment without milkfish during 1st crop. Although significantly (p < 0.05) higher total
productivity of 1931.64 kg ha
−1
was found in presence of all species, significantly
(p < 0.05) higher tiger shrimp productivity of 352.72 ± 11.49 kg ha
−1
was found in
treatment void of milkfish with total productivity of 1739.42 kg ha
−1
and best benefit cost ratio (BCR) of 2.79: 1. Similarly, significant (p < 0.05) higher harvest
weights of all fin fishes with high condition parameters were observed in treatment
without milkfish during 2nd crop. Total productivity of 3599.32 kg ha
−1
, tiger
shrimp productivity of 703.07 ± 29.33 kg ha
−1
and BCR of 2.45: 1 were significantly (p < 0.05) higher in the treatment. Higher productivity of tiger shrimp in spite
of lower harvest weights owing to higher survival and higher harvest weights of fin
fishes with higher productivity in absence of milkfish indicates differential mode of
competition by the fish with tiger shrimp and fishes. According to Dr. Subhra Bikash
Bhattacharyya and Dr. Asish Mondal this technology of reducing the competition
by stocking different species in the same water body may bring a success in the
aquaculture based economic profile in deltaic Sundarbans. The results of 1st and
Polyculture of Commercially Important Fishes
ment of productivity in polyculture. Species combination and their compatibility
are of great concern to achieve higher productivity and profitability in polyculture
but information in this context is scanty.
In this context a project initiated by Dr. Subhra Bikash Bhattacharyya and Dr.
Asish Mondal during 2013 to 2015 aimed to evaluate different species combinations in brackishwater polyculture to assess their compatibility thereby increasing
production and profitability. Different species combinations were tested involving
commonly cultivated tiger shrimp (Penaeus monodon Fabricius, 1798) and three
varieties of fishes namely parsia (Liza parsia Hamilton, 1822), grey mullet (Mugil
cephalus Linnaeus, 1758) and milkfish (Chanos chanos Forsskål, 1775).
Consequences of intensification with increased stocking density of tiger shrimp
being the highest revenue earner and addition of a local high value fish, tade mullet
(Liza tade, Forsskål, 1775) were also tested in the later phase. Main aim was to
achieve better production and profitability in a sustainable manner.
The study was carried out at Manmathapur-Mundapara village (21.879493–
21.894148°N, 88.263668–88.276199°E), Kakdwip, South 24 Parganas, West
Bengal, India at the bank of Kalnagini River. All species were reared together as
control and one fish species was eliminated for each treatment in triplicate ponds
(300–500 m
2
) for both the crops. Tiger shrimp (Penaeus monodon Fabricius, 1798),
parsia (Liza parsia Hamilton, 1822), grey mullet (Mugil cephalus Linnaeus, 1758)
and milkfish (Chanos chanos Forsskål, 1775) were polycultured for 240 days at
respective stocking densities of 20,000, 5000, 5000 and 2500 numbers ha
−1
during
April to December, 2013. The species combinations were evaluated again in 300 days
rearing with increased stocking density of 40,000, 10,000 and 5000 numbers ha
−1
for
tiger shrimp, parsia and milkfish, respectively and added with tade mullet (Liza tade,
Forsskål, 1775) at stocking density of 5000 numbers ha
−1
during August, 2014 to
June, 2015 where tiger shrimp was harvested after 150 days. Growth, production,
economic, water quality and feeding ecology parameters were evaluated.
Significantly (p < 0.05) higher harvest weights and condition factors with isometric or positive allometric growths of all fin fish species were observed in treatment without milkfish during 1st crop. Although significantly (p < 0.05) higher total
productivity of 1931.64 kg ha
−1
was found in presence of all species, significantly
(p < 0.05) higher tiger shrimp productivity of 352.72 ± 11.49 kg ha
−1
was found in
treatment void of milkfish with total productivity of 1739.42 kg ha
−1
and best benefit cost ratio (BCR) of 2.79: 1. Similarly, significant (p < 0.05) higher harvest
weights of all fin fishes with high condition parameters were observed in treatment
without milkfish during 2nd crop. Total productivity of 3599.32 kg ha
−1
, tiger
shrimp productivity of 703.07 ± 29.33 kg ha
−1
and BCR of 2.45: 1 were significantly (p < 0.05) higher in the treatment. Higher productivity of tiger shrimp in spite
of lower harvest weights owing to higher survival and higher harvest weights of fin
fishes with higher productivity in absence of milkfish indicates differential mode of
competition by the fish with tiger shrimp and fishes. According to Dr. Subhra Bikash
Bhattacharyya and Dr. Asish Mondal this technology of reducing the competition
by stocking different species in the same water body may bring a success in the
aquaculture based economic profile in deltaic Sundarbans. The results of 1st and
Polyculture of Commercially Important Fishes