Distribution and Abundance, Community Structure, and Trophic Ecology of Sharks and Teleost

140 Pages·2015·2.55 MB·English

by  Cheston Thomas Peterson

Florida State University Libraries
Electronic Theses, Treatises and Dissertations The Graduate School
2014
Distribution and Abundance, Community
Structure, and Trophic Ecology of Sharks
and Teleost Fishes in the Florida Big Bend
Cheston Thomas Peterson
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FLORIDA STATE UNIVERSITY

COLLEGE OF ARTS AND SCIENCES

DISTRIBUTION AND ABUNDANCE, COMMUNITY STRUCTURE, AND TROPHIC
ECOLOGY OF SHARKS AND TELEOST FISHES IN THE FLORIDA BIG BEND

By

CHESTON THOMAS PETERSON

A Thesis submitted to the
Department of Biological Science
in partial fulfillment of the
requirements for the degree of
Master of Science

Degree Awarded:
Spring Semester, 2014
Cheston Thomas Peterson defended this thesis on April 2, 2014.
The members of the supervisory committee were:

Dean Grubbs
Professor Directing Thesis

Joe Travis
Committee Member

Walter Tschinkel
Committee Member

The Graduate School has verified and approved the above-named committee members, and
certifies that the thesis has been approved in accordance with university requirements.

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I dedicate this to my grandfather, Chester ‘Pop’ Onks, and my dear friend, Troy Billington.

“Fare thee well, fare thee well
I love you more than words can tell
Listen to the river sing sweet songs to rock my soul”
- Robert Hunter, Brokedown Palace

“Flight of the seabirds, scattered like lost words
Wheel to the storm and fly”
- John Perry Barlow, Cassidy

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ACKNOWLEDGMENTS

Many people have contributed this work, and it is impossible to list them all. First, I
would like to thank my advisor, mentor, and friend Dean Grubbs, whose remarkable intelligence,
gentle guidance, and strong patience saw me through this entire process. I thank my committee
members, Joe Travis and Walter Tschinkel, for their thoughtful comments and suggestions which
improved both this research and my ability to think about science and statistics.
Many people provided assistance in the field for this work, and without them this work
would not have been possible. Specifically, I thank Travis Richards, Ale Mickle, Matthew
Kolmann, Lisa Hollensead, Mariah Pfleger, Erica Holdridge, and Johanna Imhoff. Countless
undergraduate and outside volunteers gave up their time for this work, and I am profoundly
grateful for their help.
This work was part of the Gulf Shark Pupping and Nursery (GulfSPAN) survey
conducted by the NOAA/NMFS fisheries lab in Panama City, Florida. I thank Dana Bethea and
John Carlson for annual funding of the survey, gillnets, and shark tags; all of which facilitated
this research.
I had a great group of colleagues with whom I could discuss my research with, both
formally and informally: Travis Richards, Johanna Imhoff, Matthew Kolmann, Lisa Hollensead,
Mollie Taylor, Robert Ellis, as well as the many EERDG participants.
This work funded by through GulfSPAN funding provided by NOAA/NMFS, as well a
research awards granted through Florida Sea Grant and funded by the Guy Harvey Ocean
Foundation, as well as a grant awarded to Dean Grubbs by the Guy Harvey Ocean Foundation.
Finally, I thank my family and friends for their continued love and support.

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TABLE OF CONTENTS
List of Tables ................................................................................................................................ vii
List of Figures .............................................................................................................................. viii
Abstract ..........................................................................................................................................xv
1. ABUNDANCE, DISTRIBUTION, AND COMMUNTIYCOMPOSTIION OF SHARKS
AND TELEOST FISHES IN THE FLORIDA BIG BEND ....................................................1
1.1 Introduction ....................................................................................................................1
1.2 Materials and Methods ...................................................................................................3
1.2.1 Study Area ........................................................................................................3
1.2.2 Survey Design ...................................................................................................3
1.2.3 Sampling ...........................................................................................................4
1.2.4 Abundance and Distribution of Dominant Species ...........................................5
1.2.5 Community Composition and Environmental Correlates .................................6
1.3 Results ............................................................................................................................8
1.3.1 General Results .................................................................................................8
1.3.2 Abundance and Distribution of Dominant Species ...........................................9
1.3.3 Community Composition and Environmental Correlates ...............................12
1.4 Discussion ....................................................................................................................16
1.4.1 Ubiquitous Species..........................................................................................16
1.4.2 Sexual Segregation in Sharks..........................................................................17
1.4.3 Regional Faunal Zones ...................................................................................18
1.4.4 Community Composition and Environmental Correlates ...............................19
1.4.5 Conclusion ......................................................................................................22

2. STABLE ISOTOPE ECOLOGY AND TROPHIC STRUCTURE OF SHARK AND
TELEOST FAUNAL ASSEMBLAGES IN THE BIG BEND .............................................70
2.1 Introduction ..................................................................................................................70
2.2 Materials and Methods .................................................................................................71
2.2.1 Sample Collection and Preparation .................................................................71
2.2.2 Stable Isotope Analysis ...................................................................................72
2.2.3 Statistical Analysis ..........................................................................................73
2.3 Results ..........................................................................................................................74
2.3.1 General Results for All Taxa ..........................................................................74
2.3.2 Ontogenetic Shift in Dominant Taxa ..............................................................77
2.3.3 Regional Variation in Stable Isotope Values ..................................................77
2.4 Discussion ....................................................................................................................78
2.4.1 General Results for All Taxa ..........................................................................78
2.4.2 Ontogenetic Shifts in Dominant Taxa .............................................................82
2.4.3 Regional Variation in Stable Isotope Values ..................................................83
2.4.1 Conclusion ......................................................................................................84
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APPENDICES .............................................................................................................................105
A. RANK ABUNDANCE CURVES AND OMISSION OF RARE SPECIES .......................105
B. NMDS DIMENSIONS AND STRESS ...............................................................................106
C. STATION COORDINATES AND CLUSTER DESIGNATIONS .....................................107
D. ACUC LETTER OF APPROVAL ......................................................................................112
REFERENCES ............................................................................................................................113
BIOGRAPHICAL SKETCH .......................................................................................................122

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LIST OF TABLES
1 Summary of environmental parameters of sites sampled within each survey region.
Means and standard deviations are shown with ranges in parentheses. Mean depth
included maximum and minimum depths of each site. For salinity, temperature, and
dissolved oxygen, each line represents surface, mid, and bottom values from top to
bottom, respectively ...........................................................................................................23

2 Summary of elasmobranch fishes; longline CPUE ([catch/100 hooks]/hours soaked
*100), gillnet CPUE (catch/hours soaked); SE = standard error; m = male, f = female;
YOY = young-of-the-year, Juv = juvenile, Mat = mature, FL = fork length, TL = total
length, DW = disc width, Individuals for which sex and/or life stage were not recorded
were omitted for calculation of sex and maturity ratios ....................................................24

3 Summary of bony fishes in taxonomic order by family; LL CPUE ([catch/100
hooks]/hours soaked*100), GN CPUE (catch/hours soaked); SE=standard error; FL=fork
length..................................................................................................................................25

4 Diversity indices of each survey region .............................................................................27

5 Results of indicator species of gillnet cluster analysis. Data shown for the cluster for
which each species’ indicator value was highest. Species in bold were significant
indicators. ...........................................................................................................................28

6 Results of indicator species analysis of longline clusters. Species in bold were significant
indicators ............................................................................................................................30

7 Summary of elasmobranch fish stable isotope values; SE = standard error; YOY = young-
of-the-year, Juv = juvenile, Mat = mature .........................................................................86

8 Summary of bony fishes stable isotope values; SE = standard error .................................87

9 Results of Tukey’s HSD tests on mean isotope values of elasmobranchs. Cownose rays
were not included in the δ15N test due to their depleted δ13C relative to other taxa.
Pairwise comparisons were significant at p < 0.05 ............................................................90

10 Sample-size corrected standard ellipse area (SEA ) of the four dominant shark species
C
and both catfishes ...............................................................................................................91

11 Pooled regional stable isotope values of dominant species and results of Tukey’s HSD
test. Pairwise comparisons were significant at p < 0.05 ....................................................91

12 Station number by gear, latitude and longitude, and cluster designation. .......................107

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LIST OF FIGURES
1 USGS GIS layer of seagrass coverage in the Big Bend .....................................................31

2 All sampling stations in the Big Bend. General survey regions are labeled. Dark circles
represent longline sets and triangles represent gillnet sets ................................................32

3 Primary (a) and secondary (b) bottom types of sampling sites within survey regions ......33

4 Total number of elasmobranch and teleost species in gillnet and on longline ..................34

5 Shark size selection of each gear type. Longline range was 28.5-302.0 cm TL. Gillnet
range was 32.0-167 cm TL ................................................................................................34

6 Length frequencies of blacknose sharks captured on longline in each survey region .......35

7 CPUE of blacknose sharks (Carcharhinus acronotus) in gillnet [catch/hours soaked] (top)
and on longline [(catch/100 hooks)/hours soaked * 100] (bottom). Means for each life
stage within each survey region are shown, error bars indicate standard error. No mature
blacknose sharks were captured in gillnet .........................................................................36

8 Map of gillnet and longline CPUE of blacknose sharks (Carcharhinus acronotus) .........37

9 Length frequencies of blacktip sharks (Carcharhinus limbatus) captured on longline in
each survey region .............................................................................................................38

10 CPUE of blacktip sharks (Carcharhinus limbatus) in gillnet [catch/hours soaked] (top)
and on longline [(catch/100 hooks)/hours soaked * 100] (bottom). Means for each life
stage within each survey region are shown, error bars indicate standard error .................39

11 Map of gillnet and longline CPUE of blacktip sharks (Carcharhinus limbatus) ..............40

12 Length frequencies of Atlantic sharpnose sharks (Rhizoprionodon terraenovae) captured
on longline in each survey region ......................................................................................41

13 CPUE of Atlantic sharpnose sharks (Rhizoprionodon terraenovae) in gillnet [catch/hours
soaked] (top) and on longline [(catch/100 hooks)/hours soaked * 100] (bottom). Means
for each life stage within each survey region are shown, error bars indicate standard error
............................................................................................................................................42

14 Map of gillnet longline CPUE of Atlantic sharpnose sharks (Rhizoprionodon
terraenovae) .......................................................................................................................43

15 Length frequencies bonnethead sharks (Sphyrna tiburo) captured in gillnet in each survey
region .................................................................................................................................44

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16 CPUE of Bonnethead sharks (Sphyrna tiburo) in gillnet [catch/hours soaked]. Means for
each life stage within each survey region are shown, error bars indicate standard error ..45

17 Map of gillnet CPUE of bonnethead sharks (Sphyrna tiburo) ...........................................45

18 Sex ratios of each life stage for blacknose, blacktip, Atlantic sharpnose, and bonnethead
sharks .................................................................................................................................46

19 CPUE of (a) Hardhead catfish (Arius felis) and (b) gafftopsail catfish (Bagre marinus) in
gillnet and on longline. Longline CPUE = [(catch/100 hooks)/hours soaked * 100] and
gillnet CPUE = [catch/hours soaked]. Means for each gear type within each survey region
are shown, error bars indicate standard error .....................................................................47

20 Maps of gillnet and longline CPUE of hardhead catfish (Arius felis, above) and
gafftopsail catfish (Bagre marinus, below) .......................................................................48

21 Per-set species richness, Shannon diversity, Simpson’s diversity, and Pielou’s evenness
(top to bottom, respectively) of each survey region for gillnet (left) and longline (right)
............................................................................................................................................49

22 Gillnet dendrogram showing 7 clusters at 92% similarity. Numbers identify individual
stations, which are shown with latitude and longitude coordinates in Appendix C. .........50

23 From top to bottom, respectively: max depth, surface salinity, water clarity, and latitude
(bottom) of sampling stations in each gillnet cluster .........................................................51

24 All gillnet sampling sites represented by symbols according to cluster ............................52

25 NMDS plot of gillnet data with 75% standard deviation confidence ellipses around the
centroid of each cluster and lines connecting each point to its assigned cluster ...............53

26 NMDS plot of gillnet 75% standard deviation confidence ellipses around the centroid of
each cluster. Four letter codes indicate weighted average points for each species (N=25).
Visible species codes: BPAT, Brevoortia patronus (Gulf menhaden); BSMI, Brevoortia
smithi (yellowfin menhaden); CACR, Carcharhinus acronotus (blacknose shark); CARC,
Calamus arctifrons (grass porgy), CFAB, Chaetodipterus faber (Atlantic spadefish);
CLIM, Carcharhinus limbatus (blacktip shark); CNEB, Cynoscion nebulosus (spotted
seatrout); CSCH, Chilomycterus schoepfi (striped burrfish); DAME, Dasyatis americana
(southern stingray); DHOL, Diplodus holbrookii (spottail pinfish); ENAU, Echeneis
naucrates (sharksucker); ESAU Elops saurus (ladyfish); LRHO, Lagodon rhomboides
(pinfish); MCEP Mugil cephalus (striped mullet), OCHR, Orthopristis chrysoptera
(pigfish); PALB, Paralichthys albigutta (Gulf flounder); PCRO Pogonias cromis (black
drum); PPAR, Peprilus paru (American harvestfish); PSAL, Pomatomus saltatrix
(bluefish); RBON, Rhinoptera bonasus (cownose ray); RCAN, Rachycentron canadum
(cobia); SMAC, Scomberomorus maculatus (Spanish mackerel) .....................................54

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