The relationship between size at maturity and maximum size in cichlid populations corroborates the gill-oxygen limitation theory (GOLT)

Amarasinghe Upali S., . and Pauly Daniel, . The relationship between size at maturity and maximum size in cichlid populations corroborates the gill-oxygen limitation theory (GOLT). pp. 14-22. ISSN 0116-6514

Fish generally mature at a smaller fraction of their maximum sizes than birds and mammals. The farmed tilapia (Family Cichlidae) can tolerate adverse conditions that result in stunting and which also cause the fish to spawn at small size. Such spawning at small size (or early spawning) is usually perceived as a unique feature of tilapia. The mechanism that explains how stressful environmental conditions tend to reduce the maximum size that fish can reach is very general and should apply to all fish. However not all fish species are equally hardy and most fish do not survive in the stunted or dwarf form under stressful environmental conditions. Tilapia and other cichlids on the other hand can handle stressful conditions if by remaining stunted. The present study shows that tilapia and other cichlids do not spawn earlier than other teleosts. Rather they are exceptionally tolerant of stressful environmental conditions but with elevated metabolism. By reducing their growth and the maximum size they can reach stunting they also reduce the sizes at which their maturity is initiated (early spawning). This corroborates the gill-oxygen limitation theory (GOLT) which identifies spawning as an event rather than a determinant of fish growth.

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Abstract

Fish generally mature at a smaller fraction of their maximum sizes than birds and mammals. The farmed tilapia (Family Cichlidae) can tolerate adverse conditions that result in stunting and which also cause the fish to spawn at small size. Such spawning at small size (or early spawning) is usually perceived as a unique feature of tilapia. The mechanism that explains how stressful environmental conditions tend to reduce the maximum size that fish can reach is very general and should apply to all fish. However not all fish species are equally hardy and most fish do not survive in the stunted or dwarf form under stressful environmental conditions. Tilapia and other cichlids on the other hand can handle stressful conditions if by remaining stunted. The present study shows that tilapia and other cichlids do not spawn earlier than other teleosts. Rather they are exceptionally tolerant of stressful environmental conditions but with elevated metabolism. By reducing their growth and the maximum size they can reach stunting they also reduce the sizes at which their maturity is initiated (early spawning). This corroborates the gill-oxygen limitation theory (GOLT) which identifies spawning as an event rather than a determinant of fish growth.

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Item Type:	Article
AGROVOC Term:	Cichlidae
AGROVOC Term:	Tilapia
AGROVOC Term:	Freshwater fishes
AGROVOC Term:	Oreochromis niloticus
AGROVOC Term:	Spawning
AGROVOC Term:	Data analysis
AGROVOC Term:	Experimental design
AGROVOC Term:	Environmental conditions
AGROVOC Term:	Metabolism
AGROVOC Term:	Growth disorders
Depositing User:	Mr. AFANDI ABDUL MALEK
Last Modified:	24 Apr 2025 00:55
URI:	http://webagris.upm.edu.my/id/eprint/9758

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