Title: The effects of water quality on fish growth rate by using otoliths in the Okavango Delta. Case study: cichlids juveniles.
Student: Kondja Amutenya
Country of origin: Namibia
University: University of Botswana
Degree:  MPhil (Natural Resources Management)
Supervisor: Prof. W.R.L. Masamba, Mr. K. Mosepele
Year of registration: 2009
Student number: 200808224

Knowledge of the age, structure, growth and developmental rate of fish population is fundamental to estimating demographic parameters and evaluating fish ecological processes. The ability to determine fish age correctly is vital in fish biology as knowledge of age structure, growth rate and longevity of fish populations is essential for proper management. This will ensure reliable stock assessments thereby assisting in conservation and allowing for sustainable utilisation of the resources. Fish retain a record of growth in several anatomical structures: scales, otoliths and bones. Otoliths provide a clear estimate of life cycle events and environmental effects on growth rate can be obtained from measurements of sequential increment marks on otoliths. We presumed that differences in water quality along the Okavango Delta would affect juvenile cichlids growth rates, and this growth rate would explain sites differences in fish size. This study will look at the effects of water quality parameters (temperature, dissolve oxygen and pH) on growth rate of cichlid juvenile, by using otoliths and no such study have been carried out in Okavango Delta. The objectives of the proposed study are:

• To determine the effects of water quality (temperature, dissolved oxygen and pH) on:
  1. Oreochromis species juveniles (Oreochromis andersonii and O. macrochir).
  2. Tilapia species juveniles (Tilapia sparrmanii and T. rendalli).
• To study growth rate of Oreochromis species and Tilapia species under varying environmental conditions.
  1. Laboratory/controlled conditions
  2. Field/natural conditions
• To compare growth-rate between Oreochromis and Tilapia under laboratory and natural conditions.

A better understanding of water quality and growth rate relationships will be fundamental for the management of cichlid species, reliable stock assessments, assisting in conservation and allowing sustainable utilization of the resources.

Last Modified: Tue, 18 Aug 2015 12:06:30 SAST