The Biology and Culture of Tilapias

Ecology and Distribution of Tilapias

J-CL. PHILIPPART AND JCL. RUWET

Service d 'ethologie anirnale

Znstitut Ed. van Beneden

Uniuersite' de Li2ge

Quai van Beneden, 22

B-4020 Liige

Belgium

PHILIPPART, J-CL. AND J-CL. RUWET. 1982. Ecology and distribution of tila-

pias, p. 15-59. In R.S.V. Pullin and R.H. Lowe-McConnell (eds.) The bio-

logy and culture of tilapias. ICLARM Conference Proceedings 7,432 p.

International Center for Living Aquatic Resources Management, Manila,

Philippines.

This paper reviews three aspects of the ecology of tilapias: i) their geo-

graphical distribution, ii) the physical (current velocity, depth, temperature)

and chemical (salinity, alkalinity, pH, oxygen and other dissolved gases)

factors which influence this and iii) aspects of their behavioral ecology

namely feeding behavior, reproductive behavior, selection of microhabitat,

schooling behavior and movement. Maps are given showing the natural

distribution of the principal substrate-spawning genus Tilapia and the mouth-

brooding genus Sarotherodon and the history of their transfers in Africa

and introductions to other continents are tabulated.

The natural distribution of the tiiapia species depends upon: i) historico-

geological factors which led to geographical isolation and speciation, ii)

ecological factors which demonstrate the requirements and preferences of the

species mainly with regard to temperature and salinity and iii) behavioral

mechanisms relating to feediig and reproductive strategies. Data on the

natural distribution, ecological amplitude and ecoethological characteristics

could help in the selection of species for culture and introductions for fish-

eries and in the prevention of unfortunate consequences, such as unwanted

hybridization, competition for food or spawning grounds, and contamination

of pure wild strains or failure of the introduced stocks (e.g., due to unsuitable

temperature conditions, overpopulation and nanism, etc.). The dangers of

introductions made without sufficient knowledge of the biology of the

species and recipient ecosystems and the necessity for better control of fish

transfers and future research on the basic and applied ecology of tilapias are

all stressed.

Introduction

In their recent review l3alarin and Hatton (1979) concentrated on the
biology of tilapias in relation to their uses in aquaculture. However, apart
from their considerable economic importance for aquaculture and fisheries,
tilapias are important elements of biocenoses, involved in the workings of
tropical aquatic ecosystems. As such they raise a multitude of problems in
basic ecology, the study of which could have, if it had been done in advance,