Life-history strategies of Nile Tilapia Oreochromis niloticus (Linnaeus 1758) (Teleostei Cichlidae) in irrigation reservoirs of Sri Lanka


Citation

N. Bandara K. V. Sandun, . and Ajith Kumara P. A. D., . and Amarasinghe Upali S., . Life-history strategies of Nile Tilapia Oreochromis niloticus (Linnaeus 1758) (Teleostei Cichlidae) in irrigation reservoirs of Sri Lanka. pp. 222-230. ISSN 0116-6514

Abstract

As in many tropical countries reservoir fishery of Sri Lanka is dominated by the exotic cichlid Oreochromis niloticus (Linnaeus 1758). Oreochromis niloticus populations in irrigation reservoirs are expected to be under the influence of various disturbances such as changes in hydrological regimes trophic conditions and fishing pressure. In the present study an attempt was made to investigate the effect of biological productivity and fishing pressure on life history patterns of O. niloticus populations in 10 irrigation reservoirs of Sri Lanka. Oreochromis niloticus populations in environmentally stressed reservoirs exhibited low age at maturity than those inhabiting reservoirs with relatively low biological productivity. Hydraulic retention time (HRT) in reservoirs also had negative influence on size and age at maturity of O. niloticus. As length at first capture of O. niloticus is positively related to mean length at maturity these attributes have significant implications on the optimal fishing. Fishing intensity (FI) in O. niloticus populations also had negative influences on mean length and age at maturity. Hence the present study supports the opinion that altricial or opportunistic traits having faster growth and achieving maturity early in the life dominate disturbed environments and that precocial or equilibrium traits exhibiting delayed maturity occur in more stable environments. Possible shifting of life history strategies of O. niloticus to opportunistic traits due to disturbance events could be manipulated by increasing FI for smaller individuals in the population.


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Abstract

As in many tropical countries reservoir fishery of Sri Lanka is dominated by the exotic cichlid Oreochromis niloticus (Linnaeus 1758). Oreochromis niloticus populations in irrigation reservoirs are expected to be under the influence of various disturbances such as changes in hydrological regimes trophic conditions and fishing pressure. In the present study an attempt was made to investigate the effect of biological productivity and fishing pressure on life history patterns of O. niloticus populations in 10 irrigation reservoirs of Sri Lanka. Oreochromis niloticus populations in environmentally stressed reservoirs exhibited low age at maturity than those inhabiting reservoirs with relatively low biological productivity. Hydraulic retention time (HRT) in reservoirs also had negative influence on size and age at maturity of O. niloticus. As length at first capture of O. niloticus is positively related to mean length at maturity these attributes have significant implications on the optimal fishing. Fishing intensity (FI) in O. niloticus populations also had negative influences on mean length and age at maturity. Hence the present study supports the opinion that altricial or opportunistic traits having faster growth and achieving maturity early in the life dominate disturbed environments and that precocial or equilibrium traits exhibiting delayed maturity occur in more stable environments. Possible shifting of life history strategies of O. niloticus to opportunistic traits due to disturbance events could be manipulated by increasing FI for smaller individuals in the population.

Additional Metadata

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Item Type: Article
AGROVOC Term: Oreochromis niloticus
AGROVOC Term: Tilapia
AGROVOC Term: Cichlidae
AGROVOC Term: Life history
AGROVOC Term: Growth rate
AGROVOC Term: Reservoirs
AGROVOC Term: Fishing
AGROVOC Term: Fisheries
AGROVOC Term: Productivity
AGROVOC Term: Tropics
Depositing User: Mr. AFANDI ABDUL MALEK
Last Modified: 24 Apr 2025 00:54
URI: http://webagris.upm.edu.my/id/eprint/9291

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