Advanced Journal of Environmental Science and Technology

Advanced Journal of Environmental Science and Technology ISSN 2756-3251, Vol. 15 (3), pp. 001-005, March, 2024. Available online at www.internationalscholarsjournals.org © International Scholars Journals

Full Length Research Paper

Ecological exploration of Mbasa (Opsaridium microlepis) habitats in Lake Nyasa Near the Ruhuhu River

Francis M. M. Chale

Department of Life Science, Faculty of Science, Technology and Environmental Studies, The Open University of Tanzania, P.O. Box 23409, Dar es Salaam, Tanzania. E-mail: [email protected]. Tel: +255-(0)22-0754367519. Fax: +255-(0)22-2668759.

Accepted 13 December, 2023

Abstract

The ecology of Opsaridium microlepis was studied in Lake Nyasa around the Ruhuhu River. The species is endemic to the lake and is economically very important. The catches of O. microlepis have declined tremendously and it is now regarded as a threatened species. The main objective of the study was to determine the probable reasons for the decline in the species populations in the Ruhuhu River. The species was found to make spawning runs in the river during the dry season when the water turbidity was low. Juveniles of O. microlepis descended into the lake when they were about six months old with a standard length of about 5.1 cm and became pelagic at about one year old. Adult O. microlepis making the runs were found to have a mean fork length of 60 cm and mean fecundity of 54,500 eggs. The study showed that turbidity of the Ruhuhu River may be the main determinant which governs when the species spawns.

Key words: Opsaridium microlepis, Lake Nyasa, Ruhuhu River, spawning runs.