Life History of the Southern Kingfish, Menticirrhus Americanus, from the North-Central Gulf of Mexico
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The University of Southern Mississippi The Aquila Digital Community Master's Theses Fall 12-2012 Life History of the Southern Kingfish, Menticirrhus americanus, from the North-Central Gulf of Mexico Samuel Dee Clardy University of Southern Mississippi Follow this and additional works at: https://aquila.usm.edu/masters_theses Recommended Citation Clardy, Samuel Dee, "Life History of the Southern Kingfish, Menticirrhus americanus, from the North- Central Gulf of Mexico" (2012). Master's Theses. 444. https://aquila.usm.edu/masters_theses/444 This Masters Thesis is brought to you for free and open access by The Aquila Digital Community. It has been accepted for inclusion in Master's Theses by an authorized administrator of The Aquila Digital Community. For more information, please contact [email protected]. The University of Southern Mississippi LIFE HISTORY OF THE SOUTHERN KINGFISH, MENTJCJRRHUS AMERJCANUS, FROM THE NORTH-CENTRAL GULF OF MEXICO by Samuel Dee Clardy A Thesis Submitted to the Graduate School of The University of Southern Mississippi in Partial Fulfillment of the Requirements for the Degree of Master of Science Approved: December 2012 ABSTRACT LIFE HISTORY OF THE SOUTHERN KINGFISH, MENTICIRRHUS AMERJCANUS, FROM THE NORTH-CENTRAL GULF OF MEXICO by Samuel Dee Clardy December 2012 Southern kingfish, Menticirrhus americanus, is a common sciaenid along the north-central Gulf of Mexico (GOM), but annual harvest has declined over the last decade. Little is known about the life history of southern kingfish in the north-central GOM, and thus the objectives of this study are to establish the spawning season, spawning frequency, fecundity, sex ratio, female size at 50% maturity, age, and standard morphometries. Specimens were collected using hook and line in several locations within the Mississippi Sound. A total of 519 southern kingfish ( 434 females, 85 males) were captured from April 2008 through May 2009 by hook and line and consisted of age classes from age 0 to 4 with the population dominated by age 1 and 2 individuals. Annuli formation occurred in May and June based on marginal increment data. The size at 50% sexual maturity for females was estimated at 189 rnm TL at age 1, although few immature female fish were captured. GSI values and overall histological ovarian maturity phases indicated that fish begin rapid gonadal development in February and March. Actively spawning females were found from April through September, although some spawning capable fish were still collected in early October. Southern kingfish are batch spawners with asynchronous oocyte development, and mean relative batch fecundity was 231.10 ± 35.68 (mean ± SE) eggs/g ovary-free body weight. Spawning frequency averaged 6.93 days between spawns from April through September, with 11 highest spawning frequency occurring in mid-summer (June and July). The reproductive strategy ofM. americanus is similar to that of other sciaenids in the GOM, although both relative batch fecundity and spawning frequency are lower than most other members of the family. The results from this study should strengthen the overall knowledge about this species and will provide resource managers valuable information to better assess population dynamics of the southern kingfish in the north-central GOM. lll ACKNOWLEDGMENTS As a full time employee at the Gulf Coast Research Laboratory's (GCRL) Marine Education Center (MEC) since 2004, it was with great enthusiasm that I enrolled in graduate school through The University of Southern Mississippi's Department of Coastal Sciences. First, I would like to thank Dr. Richard Fulford who served as my initial advisor and helped shape the project. Next, I would like to thank Dr. Mark S. Peterson who was willing to serve as my advisor in recent years. Dr. Peterson was a tremendous help throughout the project and was invaluable in aiding with the statistical analysis. I would also like to thank Nancy J. Brown-Peterson who helped me craft this project and shared her vast knowledge on the reproductive biology offish. Thanks to Gary Gray who mentored me on the proper techniques of using otoliths to establish fish age and for his constant willingness to answer questions and sacrifice his time. Thanks go to Dr. Chet Rakocinski who always had words of encouragement and for serving on my graduate committee. I would like to thank all of the MEC and Center for Fisheries Research and Development (CFRD) staff for their support and would like to particularly mention Chris Snyder, Mary Anne Dykes, Margaret Firth, and Beth Jones from the MEC and Read Hendon, Jim Franks, John Anderson, and Bill Dempster from the CFRD. I would like to thank the individuals who helped me collect fish for this project, including, but not limited to Darcie Graham, Monty Simmons, Larry Bosarge, Michael Carley, Scott Yuratich, and Scott Talley. This project would not have been possible without the tremendous support of my family, including my wife, Michelle, my children, Cody, Clayton, and Cole, and my mom and dad, Ben and Sarnrnie Lou Clardy. lV TABLE OF CONTENTS ABSTRACT .. ........................................................................................................ ........... ii ACKNOWLEDGMENTS ............ .............................................................................. .... iv LIST OF TABLES ..................................... .. ............ ....................................................... vi LIST OF ILLUSTRATIONS ...................................................................... ................... vii CHAPTER I. INTRODUCTION ..................................................................... ............... 1 II. METHODS ................. .............................................................................. 5 Sample Collection Aging Histology Spawning Frequency Fecundity Data Analysis Ill. RESULTS .............................................................. ................................. 16 Collection Age Structure and Morphometries Reproductive Biology IV. DISCUSSION ........... .................. ............................................................ 32 APPENDIXES ....... ...... ................................................................................................... 40 LITERATURE CITED .............. .. ...... .............................................................................42 v LIST OF TABLES Table 1. Reproductive Classification Terminology .......................................................... 11 2. Modified Gilson's Fluid ................................................. .. ...... ............................. 13 3. Sample Size (n), Mean Total Length (TL, mm) and Minimum and Maximum TL Values of Southern Kingfish by Month and Gender ............................ 16 4. Summary of Equations and Related Statistics for Southern Kingfish ............... .17 5. Southern Kingfish Margin Code Percent Frequency by Month (n = 123) ........ 19 6. Age Distribution by Gender and Pooled in the Sampled Southern Kingfish Population from the North-Central Gulf of Mexico ........................................... 19 7. Female Southern Kingfish Spawning Phase Percentages by Month Based on Histological Analysis. Actively Spawning is a Sub-phase of the Spawning Capable Phase ............... ...................................................................................... 23 8. Seasonal Spawning Frequency for the Southern Kingfish in the North-Central Gulf of Mexico using both POF and OM Calculation Methods ......................... 28 9. Batch Fecundity and Relative Batch Fecundity (Mean ± SE) by Month and Age Class for Southern Kingfish from the North-Central Gulf of Mexico ....... 30 Vl LIST OF ILLUSTRATIONS Figure 1. Annual harvest of southern kingfish from Mississippi waters .............................. 3 2. Map ofhook and line and crab pot sample locations where southern kingfish were sampled in the north-central Gulf of Mexico ...............................................6 3. Transverse section of a sagittal otolith on a 4+ year old southern kingfish ........ 18 4. Marginal otolith increments (mean ± SE) of southern kingfish (pooled by gender and age) by month, February (F) through November (N) ....................... l8 5. Graph of age (mean±SE) in relation to total length (TL) for male (n = 43) and female (n = 80) southern kingfish from the north-central Gulf of Mexico ........ .20 6. Plot of percentage of mature female southern kingfish (those that have entered the reproductive cycle) by 10 mrn TL size class ................................................. 21 7. Plot ofGonadosomatic Index (GSI; mean±lSE) for the southern kingfish in the north-central Gulf of Mexico with diamonds representing females and squares representing tnales ............. ............ ......... ............................................................ 22 8. Photomicrographs of reproductive phases in southern kingfish ovaries ........... .25 9. Photomicrographs of spawning capable phase in southern kingfish ovaries ...... 26 10. Photomicrographs of regressing phase of a southern kingfish ovary ........ .........27 11. Oocyte size frequency distribution in southern kingfish from a spawning capable fish (A) and an actively spawning fish (B) from the north-central Gulf of Mexico ..................... ..... .............................................. .................................... 29 12. Relationship between batch fecundity and ovary-free body weight for southern kingfish in the north-central