aspects of the biology, artisanal fishery, and feeding ecology of a ray assemblage from bahia almejas

503 Pages·2007·4.46 MB·English

FISHERY BIOLOGY AND FEEDING ECOLOGY OF RAYS IN BAHÍA ALMEJAS,
MEXICO

A thesis submitted to the faculty of
San Francisco State University
In partial fulfillment of
The requirements for
The degree

Master of Science
In
Marine Science

by
Joseph John Bizzarro
San Francisco, California
December, 2005
Copyright by
Joseph John Bizzarro
2005

ACKNOWLEDGMENTS

I consider my thesis committee to be the greatest ever assembled for my subject
matter. Dr. Enric Cortés’ advice was especially valuable in the design and analysis of my
third chapter (feeding ecology). Dr. Lara Ferry-Graham has an incredible knack for
organization, presentation, and pragmatism. She was very helpful throughout the analysis
and editing process and provided me with myriad ideas and critical comments. Dr. Ralph
Larson is an esteemed ecologist and a great editor. His comments greatly improved this
document. Dr. Gregor M. Cailliet, my advisor and friend, is someone for whom I have a
great deal of respect. He is an example of all that is good in science and provided me with
countless helpful suggestions and opportunities during my protracted tenure in his
ichthyology laboratory.
This study would not have been possible without the considerable assistance of
several friends and colleagues. Wade D. Smith provided unwavering moral and logistic
support throughout the duration of my enrollment at Moss Landing Marine Laboratories
(MLML). He is a great friend, a passionate and dedicated scientist, and an incomparable
field biologist. The support and companionship of Annie Beesley and Paul Collins during
1999 fieldwork were greatly appreciated. Carolina Downton Hoffmann and students of
Dr. Carlos Villavicencio-Garayzar’s Laboratorio de los Elasmobranquios at the
Universidad Autónoma de Baja California Sur and Dr. Felipe Galván-Magaña and his
students at CICIMAR were essential to the coordination of survey trips and the
attainment and storage of supplies and samples.
Several MLML faculty and staff members were also integral to the completion of
my M.Sc. degree. Joan Parker and the library staff provided me with a substantial amount
of literature, much of which was obscure and/or foreign, in a timely manner and never
restricted my numerous requests. Special thanks to Kathleen Baker and Donna Kline for
helping me navigate the SFSU system and graduate without any major dilemmas. They
were magicians. Dr. Gary Greene has employed me for almost a decade and helped me to
develop a second-career in habitat mapping and associated fish/invertebrate studies. He
has become a good friend and also has provided me with many opportunities that piqued
my scientific interests and put money in my pockets. Dr. Dave Ebert allowed me the time
and flexibility to complete my thesis while working for the Pacific Shark Research
Center, and for that I am very grateful.
I decided on a career in marine ecology during a term at the Williams College-
Mystic Seaport Program. Dr. Jim Carlton was the program director and his passion,
dedication, and superlative tutelage in the classroom and laboratory have been an
inspiration to me throughout my life. Dr. Janie Wulff and the other students on that
program also contributed to create an incredible working and social environment that I
envy to this day. I would also like to thank Dr. John J. Gilbert, who served as my
undergraduate thesis advisor at Dartmouth College and who hosted the marine biology
portion of a tropical ecology program that I participated in and treasured during my
senior year.
Finally, I would like to thank my family and friends, who mean more to me than
anything else. My parents taught me the importance of education at an early age and
always encouraged me to pursue what I enjoyed most in my studies and my career. I
cannot fully express how much their support and love has meant to me over the years.
My father (Joseph B. Bizzarro) is an avid outdoorsman and my appreciation of the
natural world was fostered through the time I spent with him “in the woods”, often at our
vacation home in the rural Catskill Mountains of upstate New York. My mom
(Bernadette M. Bizzarro) is an extremely caring and sensitive woman who is always there
with a hug and a kind word. When I think of her, it makes me smile. My brother, (Dr.
Matthew J. Bizzarro) is one of the most disciplined people that I have ever met and
combines that trait with intelligence and pragmatism. His “way” is truly inspirational to
me and I thought of him long and often during the writing of this document. Stori Oates
has made everything in my life better and I love her dearly. She is also a great editor who
helped me with my thesis much more than should be expected of any girlfriend.
I’ve enjoyed the company of many good friends during my time in graduate
school, especially: Erik Cordes, Jim McCarthy, Erica Burton, Jason Cope, Lisa Kerr,
Matt Levey, Jeff Field, Eric Sandoval, and brother Wade. I greatly appreciated and
benefited from Mason Dean’s inquisitive nature and especially our correspondence re:
Narcine. He is destined to become a monster in the field and I am looking forward to
watching it happen. I was lucky enough to have several old friends living in the area
during my graduate work, including: Chris Schin, Andrew Harris, Andy Peay, and Ben
Wang. Correspondence with Chris Maloney kept me sane, made me laugh, and provided
much needed non-scientific distractions; Mr. Moneschaegn, I salute you. Paul Marashlian
is my A.C. Cowlings in times of crisis and my Dean Martin when times are good. We are
long-term survivors of the west coast experiment.
Funding for this project was provided by the: David and Lucile Packard
Foundation, Homeland Foundation, JiJi Foundation, California Sea Grant College
System, PADI Project Aware, General Services Foundation, World Wildlife Fund,
Christensen Fund, Moss Landing Marine Laboratories, Mote Marine Laboratory, Instituto
Nacional de la Pesca, Dr. Earl H. and Ethyl M. Myers Oceanographic and Marine
Biology Trust, and National Oceanic and Atmospheric Administration/National Marine
Fisheries Service (to the National Shark Research Consortium, Pacific Shark Research
Center). My parents provided fortuitous supplemental funding throughout the duration of
this study. This project was conducted in accordance with and under the approval of the
SFSU Committee for the Protection of Human and Animal Subjects Protocol #02-030.
TABLE OF CONTENTS

List of Tables. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xi
List of Figures. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xx
List of Appendices. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xxxvi
VOLUME 1 ⎯ CHAPTER 1 AND CHAPTER 2

CHAPTER 1 ⎯ Physical and biological characteristics of the Bahía Magdalena Lagoon
Complex (Baja California Sur, Mexico), with comments on elasmobranch faunal
composition and nursery utilization. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1
Abstract. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Materials and Methods. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6
Results and Discussion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Physical Characteristics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Biological Characteristics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25
Fisheries. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
Elasmobranchs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
Conclusions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
Acknowledgements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
Literature Cited. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64

CHAPTER 2 ⎯ The artisanal ray fishery of Bahía Almejas (Baja California Sur,
Mexico). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107
Abstract. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108
Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
Materials and Methods. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .115
Field Methods. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .115
Data Analysis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .117
Results. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120
Artisanal Fishing Camps and Related Activities. . . . . . . . . . . . . . . . . . . . . 120
Catch Composition – Puerto Viejo. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .122
Catch Composition – Additional Camps. . . . . . . . . . . . . . . . . . . . . . . . . . . 126
Sex Ratios. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .127
Size Composition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129
Morphometric Relationships. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 134
Biomass and Numerical Landings Estimates. . . . . . . . . . . . . . . . . . . . . . . .137
Discussion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139
Acknowledgements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165
Literature Cited. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 166

VOLUME 2 ⎯ CHAPTER 3

CHAPTER 3 ⎯ Diet, foraging ecology, and trophic relationships of a ray assemblage
from Bahía Almejas (Baja California Sur, Mexico). . . . . . . . . . . . . . . . . . . . . . . . . . . . 226
Abstract. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 227
Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 228
Materials and Methods. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .236
Data Collection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .236
Data Analyses. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .241
Results. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 251
Shrinkage Experiment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 251
Rhinobatos productus. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .252
Narcine entemedor. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .259
Dasyatis dipterura. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 265
Gymnura marmorata. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .272
Rhinoptera steindachneri. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .278
Interspecific Comparisons. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 278
Discussion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 281
Diet Composition and Comparison with Congeners. . . . . . . . . . . . . . . . . .282
Dietary Overlap – Intraspecific Comparisons. . . . . . . . . . . . . . . . . . . . . . .293
Dietary Overlap – Interspecific Comparisons. . . . . . . . . . . . . . . . . . . . . . .299
Trophic Ecology. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 303
Conclusions and Recommendations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .308
Acknowledgements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .311
Literature Cited. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .313
LIST OF TABLES

Table Page

CHAPTER 1
1. Grain size (mm), classification, sorting, and dominant clast of sediment samples
collected in Bahía Almejas during August 1999. Sample collection locations are
displayed in Fig. 2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
2. Systematic list of elasmobranchs noted within the Bahía Magdalena lagoon
complex, Baja California Sur, Mexico. Species occurrences summarized from:
Castro-Aguirre and Torres-Orozco, 1993; Cruz-Agüero et al., 1994;
Villavicencio-Garayzar and Abitita-Cárdenas, 1994; Galván-Magaña et al., 2000;
and personal observations. Taxonomy follows Compagno (1999). General
eastern North Pacific distribution categorized as follows: Tropical (TR),
Subtropical (STR), Temperate (TM), and Widespread (WD). . . . . . . . . . . . . . . 94