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Studies on the Biology of Silver Catfish (Chrysichthys Nigrodigitatus Lacèpède 1803) in Jebba Lake, Nigeria

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Studies on the Biology of Silver Catfish (Chrysichthys Nigrodigitatus Lacèpède 1803) in Jebba Lake, Nigeria STUDIES ON THE BIOLOGY OF SILVER CATFISH (CHRYSICHTHYS NIGRODIGITATUS LACÈPÈDE 1803) IN JEBBA LAKE, NIGERIA BY Innocent Yakubu YEM, B. Sc (BUK), M. Sc (ABU) Ph.D/SCIE/10692/2007-2008 A THESIS SUBMITTED TO THE SCHOOL OF POSTGRADUATE STUDIES, AHMADU BELLO UNIVERSITY, ZARIA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE AWARD OF DOCTOR OF PHILOSOPHY DEGREE IN FISHERIES DEPARTMENT OF BIOLOGICAL SCIENCES, FACULTY OF SCIENCE, AHMADU BELLO UNIVERSITY, ZARIA - NIGERIA JUNE, 2014 DECLARATION I declare that this work in this dissertation entitled "Studies on the biology of silver catfish, Chrysichthys nigrodigitatus (Lacèpède, 1803) in Jebba Lake, Nigeria" has been performed by me in the Department of Biological Sciences. The information derived from the literature has been duly acknowledged in the text and a list of references provided. No part of this dissertation was previously presented for another degree or diploma at this or any other institution. Innocent Yakubu YEM Name of Student Signature Date ii CERTIFICATION This dissertation entitled "STUDIES ON THE BIOLOGY OF SILVER CATFISH, CHRYSICHTHYS NIGRODIGITATUS (LACÈPÈDE, 1803) IN JEBBA LAKE, NIGERIA" by Innocent Yakubu YEM meets the regulations governing the award of the degree of Doctor of Philosophy of the Ahmadu Bello University, and is approved for its contribution to knowledge and literary presentation. Prof. J. K. Balogun Chairman, Supervisory Committee Signature Date Department of Biological Sciences, Ahmadu Bello University, Zaria Prof. J. Auta Member, Supervisory Committee Signature Date Department of Biological Sciences, Ahmadu Bello University, Zaria Dr. N. O. Bankole Member, Supervisory Committee Signature Date Natural Resources Management, National Institute for Freshwater Fisheries Research, New-Bussa Prof. A. K. Adamu Head, Signature Date Department of Biological Sciences, Ahmadu Bello University, Zaria Prof. K. Bala Dean, School of Postgraduate Studies Signature Date Ahmadu Bello University, Zaria iii ACKNOWLEDGEMENTS I thank God Almighty the Creator and maker of all things for His love, grace, mercy and protection over me throughout the period of this work. My profound gratitude goes to Prof. J. K. Balogun, Chairman, supervisory committee for his encouragement, scholarly advice and dedication to make this research a success. I wish to thank Prof. J. Auta, member of the supervisory committee for his time, positive contributions and comments that gave this study a face lift. I appreciate Dr. N. O. Bankole for his advice, encouragement and provision of relevant literatures that contributed in no small measure to the successful completion of this research. You are all wonderful and great mentors. I am forever grateful and God bless all of you richly in the name of Jesus Christ. My most profound gratitude goes to the immediate past Executive Director/CEO, National Institute for Freshwater Fisheries Research, New Bussa, Niger State, Dr. A. Raji, for granting me the opportunity to undertake this programme. God bless, protect and continue to promote you. I acknowledge and thank the former Director of Research, Dr. A. N. Okaeme who is currently the Executive Director/CEO of the Institute, for continuing where his predecessor stopped; his encouragement and advice are inestimable. God will grant you wisdom and understanding to pilot the affairs of the Institute successfully. I wish to thank Prof. A. K, Adamu, Head of Department of Biological Sciences, Ahmadu Bello University Zaria, academic and non-academic staff of the department for their support in one way or the other for making this study a huge success. God reward you all. I am truly indebted to my wonderful parents Mr. and Mrs. Yakubu Yem Kashe, Brothers Joseph, Emmanuel, Benjamin, Sisters Rahila, Esther and Mercy for their understanding, moral support, encouragement and prayers. God will bless, protect and sustain all of you in the name of Jesus Christ. I will not forget to acknowledge the following people who contributed in one way or the other to the successful completion of this study: Dr. W. S. Omorinkoba, Anna Joshua, Pastor Sunday, Olarewaju Ajayi, Jonathan Omoridion, Usman Ibrahim, Jimoh Ademola, Akeem, Sanni Omeiza, Peter Ibrahim, Mrs. Victoria Kalangu, Talatu Lenge, Mr and Mrs. T. Biyontubo, Rilwanu Umar, Suleiman A., Tanko Garba, Ado Faku, Sani Mamman and others too numerous to mention. I am most grateful and God bless you all. iv ABSTRACT Studies on the biology of silver catfish Chrysichthys nigrodigitatus (Lacèpède, 1803) in Jebba Lake, Nigeria was carried out between January 2009 and December 2010. Samples collected using fleets of experimental gillnets were used for the study. There was fluctuations in the physico-chemical parameters measured; mean electrical conductivity (66.41±13.89µs/cm), and mean phosphate (0.20±0.15mg/l), which was significantly different (p<0.05) at the zones. The males and females showed allometric (2.49) and isometric (3.18) growth pattern respectively, with strong relationship and direct proportionality between length-length for males (0.93) and females (0.83). The condition factor for males (K=1.74) and females (K=1.83) showed that the lake was conducive for the survival of the fish because it was greater than 1. The positive correlations in the morphometric parameters, and the meristic counts confirmed the presence of the species in the lake. The age structure was between 0+ and 3+ with bulk of the samples within ranges of 2 and 2+, males being bigger than females. Size distribution ranged from small to adult, with few adults in the population. Chrysichthys nigrodigitatus has the tendency to grow bigger based on the growth performance index. Nine (9) major items ingested by C. nigrodigitatus ranged from plant materials (21.75%) to animal components (55.65%), which vary in abundance across months and seasons. Juveniles and sub-adult fed predominantly on insects (36.72% and 28.69), while adults on fry (27.86%). There was a direct relationship between the size of fish and ingested food items. Prey importance index showed insects (57.61%), insects (53.70%) and fry (39.65%) as the most important items ingested by juveniles, sub-adults and adults, respectively. There was high feeding intensity due to few number of fish stomachs without food. Chrysichthys nigrodigitatus is an omnivore with moderate gut length. There were more males than females (1.77:1) in the v population. More gravid females were recorded in August and September, which coincide with the period of spawning. Gonad maturity showed stages I-VI, males attained first maturity than females. Female C. nigrodigitatus had higher gonado-somatic index (9.73) than males (1.32) especially during the wet season. Mean fecundity ranged between 1,670- 3,375 eggs, which increase with increased in fish size. Chrysichthys nigrodigitatus was the most abundant species both within the family Claroteidae (13.06%) and in the overall catch (8.95%) during wet than dry seasons, dominant in zones I and II during the wet season, and commonly found at the bottom of the lake. It is recommended that morphometric and meristic parameters be used to identify the fish, study on population structure to reveal more class sizes be done, culture trials should also be done, and the feed components to be plant and animals materials. vi TABLE OF CONTENTS Content Page Title page ……………………………………………………………….. i Declaration ……………………………………………………………….. ii Certification ……………………………………………………………….. iii Acknowledgements ……………………………………………………………….. iv Abstract ………………………………………………………………... v Table of contents ……………………………………………………………….. vii List of tables ……………………………………………………………….. xiii List of plates ………………………………………………………………. xvi List of figures ………………………………………………………………. xvii List of Appendices ………………………………………………………………. xviii Abbreviations, Definitions and Symbols …………………………………………… xx CHAPTER ONE ……………………………………………………………….. 1 1.0 INTRODUCTION …………………………………………………………. 1 1.1 Background Information ……………………………………………….. 1 1.2 Research Problems ………………………………………………………... 9 1.3 Justification of the Study ……………………………………………….. 10 1.4 Aim and Objectives of the Study ……………………………………….. 11 1.5 Hypotheses ………………………………………………………………... 12 CHAPTER TWO ……………………………………………………………….. 13 2.0 LITERATURE REVIEW …………………………………………………. 13 2.1 Physico-chemical Characteristics of Water Bodies ……………………... 13 2.1.1 Water temperature ……………………………………………………….. 14 2.1.2 Dissolved Oxygen (DO) ………………………………………………........ 15 vii 2.1.3 Hydrogen Ion concentration (pH) …………………………………………….. 17 2.1.4 Transparency …………………………………………………………………. 18 2.1.5 Total Alkalinity and Hardness …………………………………………………. 19 2.1.6 Electrical Conductivity (EC) and Total Dissolved Solids (TDS) …………....... 20 2.1.7 Turbidity and Total Suspended Solids (TSS) ………………………………….. 21 2.1.8 Phosphate …………………………………………………………………… 23 2.1.9 Nitrate …….……………………………………………………………………. 24 2.2 Growth and Age Parameters of Chrysichthys nigrodigitatus ………………. 25 2.21 Length-weight relationship and other morphometric parameters of Chrysichthys nigrodigitatus ……………………………………………....... 25 2.2.2 Age composition and structure of Chrysichthys nigrodigitatus …..................... 33 2.2.2.1 Operculum ………………………………………………………………....... 34 2.2.2.2 Otoliths ………………………………………………………………………. 35 2.2.2.3 Scale …………………………………………………………………………. 35 2.2.2.4 Others Parts …………………………………………………………………... 36 2.3 Food and Feeding of Chrysichthys nigrodigitatus …………………………… 38 2.3.1 Seasonal changes of the food of Chrysichthys nigrodigitatus items …………………………………………………………………………… 38 2.3.2 Feeding intensity
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