The future of fisheries in natural lakes under environmental stress in Tropical Asia

Petr T., . (1997) The future of fisheries in natural lakes under environmental stress in Tropical Asia. [Proceedings Paper]

The number of natural lakes in Southeast and South Asia is relatively small but some of them such as the Great Lake Tonle Sap of Cambodia Laguna de Bay in the Philippines Lake Tempe in Sulawesi and the system of lakes on the middle Kapuas and Mahakam rivers in Kalimantan are of considerable fisheries importance. Such lakes have been exposed to a high fishing pressure which has led to a diminished average fish size and to changes in the proportion of individual species in the total catch but no drastic changes in the total yield. Where water of the tributaries has been used for irrigation the lakes have experienced greater fluctuations in water level and in some cases this has made possible the encroachment of agriculture into the margins of the lake during the low water level. Agriculture has also resulted in increasing inputs of nutrients from fertilisers and in some pollution from pesticide use. An increase of sediment load in inflowing rivers due to deforestation and agricultural practices has accelerated siltation. This shallowing of lakes and increased load of nutrients have then led to invasion of shallows by aquatic plants in some lakes further aggravated by the invasion of exotic weeds such as water hyacinth. Restoration of the ecosystem health of such lakes requires much intersectoral understanding and a willingness to compromise. Government priorities and private demands on resources need to be subjected to expert opinion before their implementation. The rising environmental consciousness of governments in the region is a promising attitude and needs to be exploited in planning for the maintenance of healthy aquatic lake ecosystems and species diversity and also for rational utilisation of fish stocks using the most modern fishery management approaches.

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Abstract

The number of natural lakes in Southeast and South Asia is relatively small but some of them such as the Great Lake Tonle Sap of Cambodia Laguna de Bay in the Philippines Lake Tempe in Sulawesi and the system of lakes on the middle Kapuas and Mahakam rivers in Kalimantan are of considerable fisheries importance. Such lakes have been exposed to a high fishing pressure which has led to a diminished average fish size and to changes in the proportion of individual species in the total catch but no drastic changes in the total yield. Where water of the tributaries has been used for irrigation the lakes have experienced greater fluctuations in water level and in some cases this has made possible the encroachment of agriculture into the margins of the lake during the low water level. Agriculture has also resulted in increasing inputs of nutrients from fertilisers and in some pollution from pesticide use. An increase of sediment load in inflowing rivers due to deforestation and agricultural practices has accelerated siltation. This shallowing of lakes and increased load of nutrients have then led to invasion of shallows by aquatic plants in some lakes further aggravated by the invasion of exotic weeds such as water hyacinth. Restoration of the ecosystem health of such lakes requires much intersectoral understanding and a willingness to compromise. Government priorities and private demands on resources need to be subjected to expert opinion before their implementation. The rising environmental consciousness of governments in the region is a promising attitude and needs to be exploited in planning for the maintenance of healthy aquatic lake ecosystems and species diversity and also for rational utilisation of fish stocks using the most modern fishery management approaches.

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Item Type:	Proceedings Paper
AGROVOC Term:	FISHERIES
AGROVOC Term:	FISHERY MANAGEMENT
AGROVOC Term:	LAKES
AGROVOC Term:	ENVIRONMENTAL CONTROL
AGROVOC Term:	POLLUTION
AGROVOC Term:	ENVIRONMENTAL DEGRADATION
AGROVOC Term:	ECOSYSTEMS
AGROVOC Term:	BIODIVERSITY
AGROVOC Term:	USES
AGROVOC Term:	TROPICAL ASIA
Geographical Term:	MALAYSIA
Depositing User:	Ms. Norfaezah Khomsan
Last Modified:	24 Apr 2025 05:27
URI:	http://webagris.upm.edu.my/id/eprint/16091

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