OCCURRENCE AND RECRUITMENT OF JUVENILE ANGUILLIDS INTO THE SABAKI AND RAMISI ESTUARY

Authors

  • Lena Muthoni Gitonga Student
  • Charles Kihia Maina Egerton University
  • Mlewa Chrisestom Mwatate Pwani University
  • Thomas Mkare Pwani University
  • Celine Hanzen
  • Emmanuel Mbaru Kenya Marine Fisheries Institute
  • Gordon O'Brien University of Mpumalanga

Keywords:

Glass eels, elvers, tail pigmentation, density, composition

Abstract

Of the 19 globally known anguillid eel species, four; Anguilla mossambica, A. bengalensis, A. marmorata and A. bicolor, occur along East African rivers. Anguillid eels are globally threatened by multiple stressors and several East African species are currently categorized as near threatened. Although juvenile anguillids recruitment into estuaries is critical to life cycle completion, their identification to species level solely on morphology is problematic, without the use of tail pigmentation. Consequently, there is limited information on juvenile anguillid eels occurrence along the Kenyan rivers, hindering development of robust management strategies. This study evaluated occurrence and recruitment of juvenile anguillids into Kenyan estuaries using glass eel fyke nets and eel mops, deployed at the lower reaches of the Athi-Galana-Sabaki and Ramisi rivers. Specimen obtained from July to October, 2021, were identified, and meristic data recorded. Results showed that of the 53 juvenile anguillid eels captured, 86% were glass eels compared to elvers (13%). All specimen were captured using fyke nets and none using the eel mops.  The sizes of glass eels collected were 1.49 ± 0.08 mm, while elvers were 1.94 ± 0.03 mm. Comparison of recruitment among species suggested that, A. bengalensis was dominant, constituting (60%) of captures, followed by A. mossambica (35%) and A. bicolor (5%), while A. marmorata were absent. The Sabaki estuary, recorded a higher density (2.47 ± 0.07 ind-1) compared to Ramisi (1.60 ± 0.35 ind d-1). Furthermore, higher recruitment was recorded in August (2.63 ± 0.36) as compared to July (1.26 ± 0.04) when river discharge was 0.11m3.s-1 and 0.14m3.s-1, respectively. This study demonstrates variation in species, river and monthly juvenile anguillid eel recruitment into East African rivers, which should be inculcated into management strategies to protect both the resource and associated fishery livelihoods.

 

 

 

 

Author Biographies

Charles Kihia Maina, Egerton University

Senior Lecturer 

Department of Biological Sciences,

Egerton University, Kenya

Mlewa Chrisestom Mwatate, Pwani University

Ph.D. Professor & Dean, School of Graduate Studies,

Pwani University, P.O. Box, 195-80108, Kilifi, Kenya.

Thomas Mkare, Pwani University

1. Lecturer Pwani University

    Department of Biological Sciences, Pwani University, P.O Box 195 Kilifi, Kenya

2. Research Scientist

     Kenya Marine and Fisheries Research Institute

Celine Hanzen

Postdoctoral Researcher

School of life sciences, University of KwaZulu Natal, RSA

Emmanuel Mbaru, Kenya Marine Fisheries Institute

Senior fisheries scientist

Kenya Marine and Fisheries Research Institute

P.O. Box 81651- 80100 Mombasa, Kenya

Gordon O'Brien, University of Mpumalanga

Senior Lecturer,

School of Biology and Environmental Sciences, University of Mpumalanga, RSA

Published

01-04-2022

How to Cite

Gitonga, L. M., Maina, C. K. ., Mwatate, M. C. ., Mkare, T., Hanzen, C., Mbaru, E. . and O’Brien, G. . (2022) “OCCURRENCE AND RECRUITMENT OF JUVENILE ANGUILLIDS INTO THE SABAKI AND RAMISI ESTUARY”, Egerton University International Conference. Available at: https://conferences.egerton.ac.ke/index.php/euc/article/view/127 (Accessed: 4 February 2023).

Issue

Section

Innovations in Climate Change and Natural Resource Management