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Growth of Chanos chanos forskal and Tilapia mossambica in a fish pond-saltern complex in Las Piñas, The Philippines
29 (1982) 169-170 Elsevier Scientific Publishing Company, Amsterdam - Printed in The Netherlands
Aquucult~re,
169
Brief Technical Note GROWTH OF GHAN05 CHANOS FORSKAL AND TrLAPIA MOSSAMBICA IN A FISH POND-SALTERN COMPLEX IN LAS PINAS, THE PHILIPPINES
LEONARD PINTO Department of Biology, De Lo Safte University, 2401 Taft Avenue, D-2801 Manita {The Phi~ipp~nes~
(Accepted 19 September 1981)
Information on the production of milkfish (Chanos chalzos) in salt pans is scarce. In The Philippines, the practice of culturing fish in these ponds is common, but the ponds are operated privately by the lower income groups and production data are not readily available. Fish cultured in saltern ponds are harvested after 6 months so that during the dry season the ponds can be used for salt production. The present study was made in a saltern pond located in Las Pifias, 15 km southof M~ila,over one production period. The area of the pond was 0.140 ha with a mean depth of 0.45 m. The stocking density of C. chcnos was 2143 per ha equivalent. T. mossambica was not introduced into the pond purposely but occurred in large numbers as an intruder from the nearby canals. During the study period, salinity variation was 21 to 41*& The average q_H was 7.8, and the daily fluctuation in DO was about 7 mg/l. N03- and PO4 concentration ranges were 3.5-4.5 mg/l and 0.15-0.25 mg/l respectively. The average net production of plankton was 3.9 mg/l day-‘. The regression constants of monthly measurements of fork length and weight of randomly caught samples for both species are shown in Fig. 1. Comparing these results with regression constants from milkfish ponds in other parts of The Philipp~es by Grover and Juliano (1976) and Inland Fisheries Project (1976), the growth rate of C. chanos in this saltern pond was low. Increase in weight of C. chanos in the pond was 0.475 g/day. This is much less than the 0.82 g/day for m~kfish in monoculture ponds treated with manure as reported by Aquino (1977), and 2.31 g/day in polyculture with T. mossambica described by Grover (1973). Although the growth rate of milkfish, and therefore production, in salterns in The ~h~ippines is low compared with the widespread traditions pond farming practices, this system of aquaculture provides a significant contribution to the protein demands of the rural population. It is estimated that there are 5080 ha of salterns in The Philippines, of which 78% are used for some form of fish production {Nations Census and Statistics Office,
0044-8486~82~0000~0~0~$02.75
Q 1982 Elsevier Scientific Publishing Company
L Oo
25
Fig. 1. Regression
50
C. chaws
IOg L=-1.9@?~3.1226bgW
T-lXO5WdiCfl
lop L --1.2234+2*W4
Wei$t (9 1
constants:
100
fork length
125
QW
150
17
vs weight.
1978). The total area of brackish water ponds for fish culture is about 176 000 ha (National Census and Statistics Office, 1981). REFERENCES Aquino, J&l., 1977. Relationships between primary productivity and mifkfish production in fertilized brackish water ponds. MS Thesis, University of The Philippines, Quezon City, 69 PP. Grover, J.H., 1973. Production of milkfish in combination with common carp and Thai catfish in fertilized freshwater ponds, Philipp. J. Fish., 11 (l-2): l-8, Grover, J.H. and Juliano, R.O., 1976. Length-weight relationships of pond-raised milkfish in the Philippines. Aquaculture, 7: 339-346. Inland Fisheries Project, 1976. Technical Report No. 6. National Science Development of The Philippines, Project No. 7103.2 Ag, pp, 72-73. National Census and Statistics Office, 1978. The Salt Industry. J. Philipp. Stat., 29 (3): ix-xix. National Census and Statistics Office, 1981. Philippine Yearbook. Nat. Census Stat. Office, Manila, 1034 pp.
Aquucult~re,
169
Brief Technical Note GROWTH OF GHAN05 CHANOS FORSKAL AND TrLAPIA MOSSAMBICA IN A FISH POND-SALTERN COMPLEX IN LAS PINAS, THE PHILIPPINES
LEONARD PINTO Department of Biology, De Lo Safte University, 2401 Taft Avenue, D-2801 Manita {The Phi~ipp~nes~
(Accepted 19 September 1981)
Information on the production of milkfish (Chanos chalzos) in salt pans is scarce. In The Philippines, the practice of culturing fish in these ponds is common, but the ponds are operated privately by the lower income groups and production data are not readily available. Fish cultured in saltern ponds are harvested after 6 months so that during the dry season the ponds can be used for salt production. The present study was made in a saltern pond located in Las Pifias, 15 km southof M~ila,over one production period. The area of the pond was 0.140 ha with a mean depth of 0.45 m. The stocking density of C. chcnos was 2143 per ha equivalent. T. mossambica was not introduced into the pond purposely but occurred in large numbers as an intruder from the nearby canals. During the study period, salinity variation was 21 to 41*& The average q_H was 7.8, and the daily fluctuation in DO was about 7 mg/l. N03- and PO4 concentration ranges were 3.5-4.5 mg/l and 0.15-0.25 mg/l respectively. The average net production of plankton was 3.9 mg/l day-‘. The regression constants of monthly measurements of fork length and weight of randomly caught samples for both species are shown in Fig. 1. Comparing these results with regression constants from milkfish ponds in other parts of The Philipp~es by Grover and Juliano (1976) and Inland Fisheries Project (1976), the growth rate of C. chanos in this saltern pond was low. Increase in weight of C. chanos in the pond was 0.475 g/day. This is much less than the 0.82 g/day for m~kfish in monoculture ponds treated with manure as reported by Aquino (1977), and 2.31 g/day in polyculture with T. mossambica described by Grover (1973). Although the growth rate of milkfish, and therefore production, in salterns in The ~h~ippines is low compared with the widespread traditions pond farming practices, this system of aquaculture provides a significant contribution to the protein demands of the rural population. It is estimated that there are 5080 ha of salterns in The Philippines, of which 78% are used for some form of fish production {Nations Census and Statistics Office,
0044-8486~82~0000~0~0~$02.75
Q 1982 Elsevier Scientific Publishing Company
L Oo
25
Fig. 1. Regression
50
C. chaws
IOg L=-1.9@?~3.1226bgW
T-lXO5WdiCfl
lop L --1.2234+2*W4
Wei$t (9 1
constants:
100
fork length
125
QW
150
17
vs weight.
1978). The total area of brackish water ponds for fish culture is about 176 000 ha (National Census and Statistics Office, 1981). REFERENCES Aquino, J&l., 1977. Relationships between primary productivity and mifkfish production in fertilized brackish water ponds. MS Thesis, University of The Philippines, Quezon City, 69 PP. Grover, J.H., 1973. Production of milkfish in combination with common carp and Thai catfish in fertilized freshwater ponds, Philipp. J. Fish., 11 (l-2): l-8, Grover, J.H. and Juliano, R.O., 1976. Length-weight relationships of pond-raised milkfish in the Philippines. Aquaculture, 7: 339-346. Inland Fisheries Project, 1976. Technical Report No. 6. National Science Development of The Philippines, Project No. 7103.2 Ag, pp, 72-73. National Census and Statistics Office, 1978. The Salt Industry. J. Philipp. Stat., 29 (3): ix-xix. National Census and Statistics Office, 1981. Philippine Yearbook. Nat. Census Stat. Office, Manila, 1034 pp.