UNIVERSITY OF CAPE COAST ASPECTS OF THE BIOLOGY AND POPULATION DYNAMICS OF SPHYRAENA SPHYRAENA (LINNAEUS, 1758), APSILUS FUSCUS (VALENCIENNES, 1830) AND CYNOGLOSSUS SENEGALENSIS (KAUP, 1858) IN GHANAIAN WATERS DIVINE WORLANYO HOTOR 2020 ©2020 Divine Worlanyo Hotor University of Cape Coast UNIVERSITY OF CAPE COAST ASPECTS OF THE BIOLOGY AND POPULATION DYNAMICS OF SPHYRAENA SPHYRAENA (LINNAEUS, 1758), APSILUS FUSCUS (VALENCIENNES, 1830) AND CYNOGLOSSUS SENEGALENSIS (KAUP, 1858) IN GHANAIAN WATERS BY DIVINE WORLANYO HOTOR Thesis submitted to the Department of Fisheries and Aquatic Sciences of the School of Biological Sciences, College of Agricultural and Natural Sciences, University of Cape Coast, in partial fulfillment of the requirements for the award of Master of Philosophy degree in Fisheries Science JULY, 2020 DECLARATION Candidate’s Declaration I hereby declare that this thesis is the result of my own original research and that no part of it has been presented for another degree in this university or elsewhere. Candidate’s Signature:.................................................... Date:........................... Name: Divine Worlanyo Hotor Supervisors’ Declaration We hereby declare that the preparation and presentation of the thesis were supervised in accordance with the guidelines on supervision of thesis laid down by the University of Cape Coast. Principal Supervisor’s Signature:.................................... Date:......................... Name: Prof. Joseph Aggrey-Fynn Co-Supervisor’s Signature: ........................................... Date:......................... Name: Prof. John Blay ii ABSTRACT Despite the commercial relevance of the S. sphyraena, A. fuscus and C. senegalensis to the Ghanaian fisheries there is paucity of information on the growth, population dynamics and exploitation rates of the three stocks, as such making it nearly impossible to sustainably exploit these species in Ghana. Therefore it was reasonable to investigate aspects of the biology and population dynamics of these species as the findings would help boost management measures. A total of 420, 423 and 562 specimens of Sphyraena sphyraena, Apsilus fuscus and Cynoglossus senegalensis respectively were studied. Total length (TL) ranged from 12.5 cm to 66.5 cm for S. sphyraena, 20.3 cm to 50.9 cm for A. fuscus and 11.0 cm to 56.4 cm for C. senegalensis. A significant relationship and a strong correlation between total length (TL) and body weight (BW) was exhibited by the three species. The growth of S. sphyraena and A. fuscus were allometric (b = 2.75 ±0.11; P<0.05 for S. sphyraena and b = 2.84 ±0.12; P<0.05 for A. fuscus) while C. senegalensis showed an isometric growth pattern (b = 3.08 ±0.11; P>0.05). Condition factor range for pooled specimens of S. sphyraena was 0.41 (±0.03) to 0.60 (±0.02), 0.37 to 0.72 for males and 0.38 (±0.04) to 0.54 for females. For A. fuscus, condition factor for pooled specimens ranged from 0.93 to 1.09 (±0.03), 0.94 to 1.09 and 0.94 to 1.08 (±0.03) for females. The condition factor ranged from 0.39 to 0.68 for pooled specimens of C. senegalensis. The exploitation rate were estimated at 0.62 for S. sphyraena, 0.56 for A. fuscus, and 0.52 for C. senegalensis. In conclusion, all three species exhibited exponential growth and the condition factor recorded was higher in smaller size groups than in the larger size groups. iii KEY WORDS Asymptotic length Condition factor Growth Mortality Total length iv ACKNOWLEDGMENTS I am highly thankful to my supervisors, Prof. Joseph Aggrey-Fynn and Prof. John Blay for their patience, mentorship, ideas and feedback. I am indebted to the USAID/UCC Fisheries and Coastal Management Capacity Building Support Project for giving me this great opportunity and funding during my studies. I am grateful to Dr. Emmanuel Acheampong who encouraged and guided me to apply for the programme. I appreciate Simon Appah Aram and Isaac Osei for their support and ideas. Thanks to Delali Gamor, Michelle Clottey and Jemimah Kasa for their guidance during field and laboratory sessions. Many thanks to the laboratory technicians and drivers of the Department of Fisheries and Aquatic Sciences for not relenting on their efforts anytime I needed them. I am grateful to the entire staff and students of the Department of Fisheries and Aquatic Sciences for the diverse roles they played during the study period. I am thankful to Mr Joshua Adortey for his follow ups during the entire study period. I am grateful to Comfort Boadu for her colossal love and care. Much appreciation to my parents Mr Gilbert Frank Hotor and Mrs Martina Hotor as well as my siblings Dennis Hotor and Mrs Patricia Goode and the entire Hotor family for their special support. v DEDICATION To Mr. Frederick Ekow Jonah and the Department of Fisheries and Aquatic Sciences of the University of Cape Coast, Ghana. vi TABLE OF CONTENTS DECLARATION .............................................................................................. ii ABSTRACT ..................................................................................................... iii KEY WORDS .................................................................................................. iii ACKNOWLEDGMENTS .................................................................................v DEDICATION ................................................................................................. vi TABLE OF CONTENTS ................................................................................ vii LIST OF TABLES .............................................................................................x LIST OF FIGURES ......................................................................................... xi LIST OF ABBREVIATIONS ........................................................................ xiii CHAPTER ONE ..............................................................................................14 INTRODUCTION ...........................................................................................14 Background to the Study ..............................................................................15 Problem Statement and Justification ............................................................24 Purpose of the study .....................................................................................25 Research objectives ......................................................................................25 Significance of the study ..............................................................................26 Delimitations of the Study ...........................................................................26 Limitations of the Study...............................................................................26 Definition of Terms......................................................................................27 Organization of the Study ............................................................................27 vii Chapter Summary ........................................................................................28 CHAPTER TWO .............................................................................................29 LITERATURE REVIEW ................................................................................29 Growth .........................................................................................................29 Mortality and Exploitation ...........................................................................32 Stock assessment tool (FiSAT) ....................................................................34 Sphyraena sphyraena (Linnaeus, 1758) ......................................................35 Apsilus fuscus (Valentines, 1830) ................................................................36 Cynoglossus senegalensis (Kaup, 1858) ......................................................38 CHAPTER THREE .........................................................................................40 MATERIALS AND METHODS .....................................................................40 Study area.....................................................................................................40 Samples and Sampling Procedure ................................................................43 Data collection procedure ............................................................................44 Data processing and analysis .......................................................................44 CHAPTER FOUR ............................................................................................46 RESULTS ........................................................................................................47 Length-frequency distribution .....................................................................47 Monthly length-frequency distributions ......................................................51 Length-weight relationship ..........................................................................54 Variations in condition factor (K) ................................................................57 Sex ratio .......................................................................................................61 Growth parameters .......................................................................................63 viii Length at first capture ..................................................................................65 Mortality and Exploitation ...........................................................................67