Age and Growth of Bonefish, Albula Species Among Cuban

AGE AND GROWTH OF BONEFISH, ALBULA SPECIES AMONG CUBAN

HABITATS

JACOB JOSEPH RENNERT

B.S., University of North Carolina Wilmington

A thesis submitted to the Department of Biological Sciences of Florida Institute of Technology in partial fulfillment of the requirements for the degree of

MASTER OF SCIENCE in BIOLOGICAL SCIENCE

Melbourne, Florida November 2017

AGE AND GROWTH OF BONEFISH, ALBULA SPECIES AMONG CUBAN

HABITATS

A THESIS

JACOB JOSEPH RENNERT

Approved as to style and content by:

Jonathan Shenker, Ph.D., Chairperson Aaron Adams, Ph.D., Member Associate Professor Senior Scientist Department of Biological Sciences Harbor Branch Oceanographic Institute-FAU

Ralph Turingan, Ph.D., Member Jorge Angulo Valdes, Ph.D., Member Professor Professor Department of Biological Sciences University of Florida

John Trefry, Ph.D., Member Richard Aronson, Ph.D. Professor Professor and Head Ocean Engineering and Sciences Department of Biological Sciences

November 2017

ABSTRACT

AGE AND GROWTH OF BONEFISH, ALBULA SPECIES AMONG CUBAN HABITATS

By Jacob Joseph Rennert, B.S., University of North Carolina Wilmington

Chairperson of Advisory Committee: Jonathan Shenker, Ph.D.

Bonefish (Albula spp.) are a prized sportfish among avid anglers worldwide. Two morphologically indistinguishable species of bonefish (Albula vulpes and Albula goreensis) exist in the circumtropical waters of the western

Atlantic. A. vulpes grows faster and reaches larger sizes in the Florida Keys than in the Bahamas and other insular regions, but the mechanisms driving this variation have not been identified. Cuba supports large populations of bonefish, but their age, growth rate, and reproductive biology has not previously been examined. I obtained specimens from fish markets and local research staff in 3 regions around the periphery of Cuba from November 2016 to January 2017. Sagittal otoliths and fin clips were collected from each fish, and sex was determined by visual examination of gonads. Fin clips were sent to the Genetics Laboratory at the Florida Fish and

Wildlife Research Institute for identification. Otoliths were aged by embedding, iii

sectioning, and examining thin sections. A total of 218 bonefish were sampled, with a size range of 187-530mm FL. Genetic testing indicated that 134 were A. vulpes, 59 were A. goreensis, and 7 were hybrids. The oldest fish collected were 8 and 9 years old for A. vulpes and A. goreensis respectively. Both species of bonefish displayed gonadal development indicating the preparation to spawn in the month of November 2016. Growth of A. vulpes was rapid until the age of 5 years then slowed, with females reaching larger sizes than males. The fewer specimens for A. goreensis prevented calculation of sex-specific growth curves. Predicted fork length at age values were greater at all ages for A. vulpes compared to A. goreensis.

All bonefish collected above the size of 231mm FL with exception of one fish were found to be reproductively mature. Bonefish were observed to be reproductively mature at the age of 1 year, much smaller and younger than observed in previous studies. The insight of varying growth patterns between A. vulpes and cryptic species allows for better management of the species, and further distinguishes differences in the biology of A. vulpes and A. goreensis.

DEDICATION

I would like to dedicate this to my family, who has had my back since I was a young student and pushed me to become the scientist I am today. To the many incredible people of Cuba who treated me as if I were family and were willing to give so much when they have so little.

ACKNOWLEDGEMENTS

I would like to thank my academic advisor Jon Shenker for guiding me through this master’s program and giving me the freedom to develop into an independent scientist. Dr. Liz Wallace and Ben Kurth, staff members of the Fish and Wildlife Research Institute (FWRI) of the Florida Fish and Wildlife

Commission (FWC), who completed all of the lab work and analyses that were necessary to genetically identify each bonefish. Robby Fidler taught me everything surrounding the sectioning of otoliths, in addition to anything that involved growth analyses in R. Jessica Carroll and Kristin Cook staff members of FWC in the Age and Growth Laboratory, helped me understand the art of reading otoliths and completed the 2nd and 3rd reads for aging. Dr. William Szelistowski and Dr. Corey

Krediet professors at Eckerd College assisted in the organization of the second collection trip to Cuba. All of the students from the 2017 winter term field research assisted in the processing of bonefish obtained in January.

This project would not have been possible without the incredible collaborators in Cuba. Dr. Jorge Angulo assisted in much of the project logistics.

He sat down with me many times to brainstorm collection sites, logistics of the trip including flights, hotels, additional contacts in Cuba, and much more. Lazaro

(Lachy) Garcia and Eddy Garcia helped organize everything once we arrived in

Cuba. They were instrumental in adapting to the challenges of working in Cuba and coming up with new plans daily in order to obtain all the fish we did. Eddy and

Lachy both helped obtain and process fish throughout this entire study. My dad

Bruce Rennert joined me on the first collection trip. He helped with much of the data labeling and gave sound advice on how to become a better leader and project manager. Leo and Zai Espinosa collected and helped process bonefish from the San

Felipe region. Alexei Ruiz collected and processed bonefish from the Zapata

Swamp. Zenaida Marinez helped organize and plan many logistical aspects of the second collection trip.

I would like to thank my remaining committee members Dr. Aaron Adams,

Dr. Ralph Turingan, and Dr. John Trefry for guidance with my project, providing me with many instrumental connections, and challenging me as a scientist throughout this program.

The Bonefish and Tarpon Trust provided me with many contacts in Cuba and helped open the dialogue between US and Cuban researchers. Florida Sea

Grant and the Guy Harvey Ocean Foundation provided me with the funds to complete this study.

vii

TABLE OF CONTENTS

Page

ABSTRACT ...... iii

DEDICATION ...... v

ACKNOWLEDGEMENTS ...... vi

TABLE OF CONTENTS ...... viii

LIST OF FIGURES ...... x

LIST OF TABLES ...... xi

INTRODUCTION ...... 1

MATERIALS AND METHODS ...... 8

SITE SELECTION ...... 8

SAMPLING METHOD ...... 10

OTOLITH PROCESSING ...... 11

DATA ANALYSIS ...... 13

RESULTS ...... 14

SPECIES ABUNDANCE, DISTRIBUTION, AND SEX RATIO...... 14

BONEFISH SIZE DISTRIBUTION...... 16

BONEFISH SEX DISTRIBUTION AND GONADAL DEVELOPMENT. .

...... 20

BONEFISH AGE DISTRIBUTION...... 20

BONEFISH AGE AND GROWTH CURVES...... 23

DISCUSSION ...... 28

viii

LITERATURE CITED ...... 40

LIST OF FIGURES

Page Figure 1. Sampling regions for bonefish collected in Cuba from November 2016-2017. (A): Northcentral coast (B): Zapata Swamp (C): San Felipe Island chain...... 9

Figure 2. Micrograph of a transverse section from an 8-year-old (350mm) bonefish, Albula goreensis viewed with transmitted light source. . 12

Figure 3. Detailed map of the fishing village locations of Playa Nazabal and Juan Francisco...... 15

Figure 4. Length frequency distribution of A. vulpes collected in Cuba 2016- 2017 male n=87 and female n=30 ...... 18

Figure 5. Length frequency distribution of A. goreensis collected in Cuba 2016-2017 male n=12 and female n=42...... 19

Figure 6. Age frequency distribution of Albula vulpes collected in Cuba 2016- 2017 Male: n=87, Female: n=30...... 21

Figure 7. Age frequency distribution of Albula goreensis collected in Cuba 2016-2017 Male: n=12, Female: n=42...... 22

Figure 8. Observed FL at age and von Bertalanffy growth curve for A. vulpes males and females...... 25

Figure 9. Observed length at age and von Bertalanffy growth curve for A. goreensis collected in Cuba 2016-2017. L= Length, t=age in years...... 26

Figure 10. Predicted FL at age of A. vulpes and A. goreensis calculated from VB growth equations...... 27

Figure 11. Von Bertalanffy growth curves calculated for A. vulpes populations in the Florida Keys, the Bahamas and Caribbean, and Cuba. (Crabtree et al. 1996, Adams et al. 2008) ...... 31

Figure 12. Predicted biphasic growth curve for bonefish in FL Keys developed by Larkin (2011)...... 35

LIST OF TABLES

Page Table 1. Summary of number of Albula spp. obtained from each sampling region in Cuba collected from 2016-2017...... 16

Table 2. Summary of sample size, age range, and size range for all species of bonefish collected in Cuba from 2016-2017 ...... 17

Table 3. Summary of current study and past publications von Bertalanffy growth parameters for Albula spp. L∞= estimated maximum fork length (mm), K= growth coefficient, (mm), and n= number of fish collected...... 38

INTRODUCTION

Bonefish (Albulidae) are a mesopredator that inhabit varying types of shallow tropical and subtropical habitats, including but not limited to sand flats, mangrove-lined channels, and seagrass habitats worldwide. Initially considered to be a single circumtropical species, genetic analysis indicates that the Albulidae family consists of 11 species that have a remarkably consistent phenotype that is apparently constrained by the evolutionary selection pressure exerted within the shallow habitats (Colborn et al. 2001; Wallace and Tringali 2016). Of the 4 species of Albulidae in the western Atlantic Albula vulpes is the dominant target of many anglers and is considered a treasured sportfish. A. vulpes, and other members of the genus are listed under the International Union for the Conservation of Nature

(IUCN) Red List as Near Threatened with a downward trend in populations

(Adams et al. 2012); careful management practices and a better understanding of their biology is paramount to the successful conservation of this fishery (Adams and Cooke 2015).

As a measure of the value of their recreational fishery, Albula vulpes accounted for more than 17% of targeted angling days for south Florida, where they contributed to over 47 million dollars in salaries, wages, and business owner income in 2009 (Fedler 2009). Being so economically important, A. vulpes are heavily regulated in Florida, and were established as a catch and release fishery in

2013 by the Florida Fish and Wildlife Conservation Commission (FWC 2013).

Despite the requirement for release in Florida, and widespread voluntary release practices in the recreational fishery around the world, fishing stress does cause some mortality (Cooke and Philipp 2004, Danylchuk et al. 2007). Angling and handling practices have been studied, and recommendations have been made to reduce post release mortality by minimizing air exposure time, proper selection of hook and gear types, use of handling devices, and employing effective recovery and release procedures (Danylchuk et al. 2007, Danylchuk et al. 2008, Stein et al. 2012,

Brownscombe et al. 2013, Brownscombe et al. 2017). Although bonefish must be released after capture, in Florida, they support a consumptive and subsistence fishery in many other countries (e.g. Dominican Republic, the Bahamas, Haiti,

Cuba, etc.). Landings data from these countries are not generally available.

Living in the same regions as A. vulpes is a cryptic species, identified as

Albula goreensis that has distinct genetic differences from A. vulpes, but no distinguishing morphological characteristics (Wallace 2014). There is some habitat overlap between species, although A. goreensis typically inhabits water deeper than

1m and the majority of A. vulpes collections occurs on nearshore flats <1m in depth

(Wallace and Tringali 2010, Wallace and Tringali 2016). Juvenile A. goreensis appear to prefer shallow sandy coastline that have higher wave energy and more exposure for settlement habitat (Adams et al. 2008, C. Haak unpublished data). A. goreensis have been speculated to grow at slower rates as juveniles compared to A. vulpes (C. Haak-unpublished data), but there have not been formal studies investigating species-specific growth rates. Due to the broad overlap in range and

3 morphological similarity of the two species, the ecological and population characteristics of both species should be considered for the development of management strategies promoting the conservation of bonefish. Despite A. goreensis not being the primary bonefish species of concern, A. goreensis may persist in many habitats and locations similar and in some cases, co-exist with A. vulpes. It would be beneficial to the management of both species to conserve essential habitats and ecological processes such as spawning migrations when managing bonefish populations.

Because the existence of A. goreensis was not known until it was formally described by Wallace (2014), it is possible that some of the earlier research on A. vulpes may have included A. goreensis in the analyses. Based on earlier literature,

A. vulpes utilize tropical and subtropical shallow water nearshore habitats, including mangrove-lined creeks and embayments, seagrass beds, sand and mud flats, and other habitats in the Caribbean, Florida, and Bahamas (Colton and

Alevizon, 1983, Cooke and Philipp 2004, Danylchuk et al. 2007). Although these habitats are outwardly similar throughout the region, they are contiguous with highly diverse terrestrial ecosystems that may affect the physical and trophic structures of the shallow ecosystems, and may thus affect the feeding and growth of fishes that utilize these shallow water habitats. For example, A. vulpes inhabit the

Florida Keys, which receives a high nutrient loading from Florida Bay and the

Everglades (Gibson et al. 2008). Conversely their habitats in the Bahamas receives less terrestrial and anthropogenic nutrient input (Wankel 2003). These variations in

4 nutrient supply can potentially contribute to differences in the species composition and abundance of their prey base, resulting in varying growth rates and other biological parameters in different habitats.

Perhaps because of the differences in nutrient and trophodynamic structure among habitat, fish presumed to be A. vulpes in the Florida Keys grow larger and faster than those in the Bahamas (Crabtree et al. 1996, Adams et al. 2008). Von

Bertalanffy growth curves calculated for bonefish in each region indicate that fish in the Florida Keys reach an asymptotic maximum size (L∞) of 600-700mm FL in

7-8 years, while fish in the Bahamas rarely reached that size even after 15 years of growth (Crabtree et al. 1996, Adams et al. 2008).

Another possible reason for differences in growth rates in different regions is that latitudinal differences have been observed to cause differences in growth rates in American shad Alosa sapidissima, striped bass Marone saxatilis, and other species (Conover 1990). However, this countergradient variation hypothesis, the capacity to grow rapidly within the growing season in high-latitude environments may be an adaptive response to size-selective winter mortality (Conover 1990,

Conover et al. 1997) and may not be applicable to Albula spp. that inhabit tropical waters. An extension of the latitudinal hypothesis focuses on reproductive variability and energetics of egg production and spawning. Tarpon (Megalops atlanticus) that appear to spawn throughout the year in Costa Rica and other tropical habitats reach smaller maximum adult sizes than do tarpon in Florida that migrate to the northern Gulf of Mexico or along the Atlantic coast, have a limited

5 spawning season, and reach a larger size (Crabtree et al. 1997b).

A third hypothesis explaining varying growth rates among fish of a single species in different habitats is genetic differences. This hypothesis requires that there be some degree of genetic isolation among A. vulpes populations. Although adult A. vulpes are restricted to shallow habitats and presumably do not migrate across deep ocean channels, their leptocephalus larvae can persist in open water from 41 to 71 days before settlement occurs (Mojica et al. 1995). Having a relatively long pelagic larval duration (PLD) allows for the long-distance transport of larvae among different regions. Temporal and spatial variability in spawning times, coupled with prevailing and variable oceanographic currents, can disperse larvae to different regions causing variation in recruitment levels and genetic linkages among different regions (Hare et al. 1999; Paris et al. 2005, Siegel et al.

2008). Wallace and Tringali (2016) explicitly examined the population genetics of

Albula spp. in the Caribbean, and found evidence of intraspecific genetic structure within a region, which is likely a product of quasi-discrete spawning groups. Over the protracted spawning season, and there is potential for specific spawning groups within the same population that will spawn separately during fall and spring seasons (Wallace and Tringali 2016). If genetic differences persist among regions, but growth differences occur within both genetic variants, this would support the hypothesis that growth differences between regions are attributed to environmental factors would be supported.

Varying growth rates can have a major influence on population dynamics, ages at maturity, and the longevity of the species. Positive relationships have been observed between weight and fecundity in tarpon (Megalops atlanticus) in Florida

(Crabtree et al. 1997b). Larger sized fish are likely to produce more gametes and be more reproductively successful. Given the potential for long distance transport of leptocephalus larvae that can persist in the plankton for 41-71 days (Mojica et al.

1995), the reproductive output of one region might have implications to another in regions adjacent functioning as a metapopulation. If growth rates vary among habitats, populations in different habitats may have different levels of resilience to fishing and other environmental perturbations, which may have significant impacts on sink populations.

Fishing pressure in Cuba for bonefish consists of both a subsistence fishery and as a catch and release fisheries that exert different levels of fishing pressure in different regions of the island. No fisheries catch data are available, as most of the harvesting is for subsistence or for sale on the black market under a different species name. North coast habitats support consumptive fisheries, with gill nets employed along coastal channels and flats (J. Angulo and E. Garcia, pers. comm.).

Conversely areas such as the Zapata swamp on the south coast receives little to no harvest pressure due to its isolation, and enforced prohibition on the harvest of bonefish. The south coast has some consumptive fisheries, but also supports a valuable recreational fishing industry in locations such as Las Salinas within the

Zapata Swamp, Jardines de la Reina, Cayo Largo, and Isla de la Juventud (J.

Angulo and Avalon Cuban Fishing Center, pers. comm.).

Cryptic species are defined as biological organisms classified at one point as a single species, but have speciated into two separate, and often morphologically indistinguishable, species that are reproductively and ecologically isolated (Mayr

1943). These cryptic species may ultimately develop overlapping ranges, as has been observed in many fishes including salmon, torut, charr, sticklebacks, and cichlids (Schluter and McPhail 1992, Taylor 1999, Barluenga et al. 2006). Within the flats habitat, Wallace and Tringali (2016) determined that of the three geographically overlapping species of bonefish in the western Atlantic Ocean and

Caribbean Sea, A. vulpes is the primary contributor to the recreational fishery.

Little research has been conducted on bonefish in Cuba. Just 90 miles south of the Florida Keys, Cuba may be a potential source of larvae that drive Florida populations. Ongoing population genetics studies seek to track genetic linkage among Caribbean populations (Wallace and Tringali 2016). Analysis of age and growth of adult fish in different habitats in Cuba can ultimately be used to evaluate reproductive output from those habitats and their potential role in recruitment to other regions, thus impacting management practices and conservation efforts. This thesis presents the results of an examination of the age, growth, and reproductive status of adult bonefish in Cuba as important steps in the process of understanding the factors that influence the population dynamics of this valuable international fishery species.

MATERIALS AND METHODS

Site Selection

Samples were collected from 3 main locations around the north and south coasts of Cuba (Figure 1). Locations were chosen based on accessibility to collect fish, varying habitat types, varying types of fishing pressure, and different levels of conservation enforcement.

Region A includes the narrow northcentral shelf of Cuba that historically receives nutrient inputs from terrestrial and freshwater sources that are elevated during the rainy season (Lluis-Riera 1983). The northcentral coast receives considerable artisanal and commercial fishing pressure, and several fishing centers, which were coast guard regulated docks that several fishers were based out of within 20 km of each other, provided bonefish for this research project.

Region B includes the Zapata Swamp, which is an internationally recognized wildlife refuge that has been designated as a Ramsar site, an internationally recognized and protected wetland. The Zapata Swamp is one of few national parks in Cuba, receiving little fishing pressure and virtually no harvesting.

This national park has a significant wildlife enforcement program to protect the unique ecosystem and the valuable wildlife. There is a limited bonefish catch and release recreational fishery in the Las Salinas lagoon and other portions of the

Zapata Swamp.

Location C includes the island chain of San Felipe and surrounding waters

9 of the Bay of Batabanó. The region is characterized by reduced freshwater input into very expansive shallow water habitats that covers 10,000 km2. Over the last decade many historical freshwater inputs into this system have been dammed restricting flow into the marine system and has been a cause for decreased fisheries production (Baisre and Aroboleya 2006). Catches of species such as shrimps

(Penaeidae), mullets (Mugilidae), and mojarras (Gerridae) decreased over 20 years

(1980-2000), which was attributed to the increased occurrence of damming, blocking freshwater to areas that historically received freshwater inputs (Baisre and

Aroboleya 2006).

Figure 1: Sampling regions for bonefish collected in Cuba from November 2016- 2017. (A): Northcentral coast (B): Zapata Swamp (C): San Felipe Island chain

Sampling Method

Fisheries dependent sampling was conducted by purchasing bonefish directly from fishers and fish markets that sold fish to individual consumers or the government. Most specimens were collected with gill nets that were 100 meters in length, 2 meters in height, and mesh sized ranged from 40-70 millimeters.

Bonefish were purchased through these sources in region A and, measured, weighed, and biological samples (otoliths, fin clips, and gonadal data) were collected. After rapid processing, fish were donated back to the community for consumption. Bonefish obtained from the Zapata Swamp and San Felipe Island chain were collected with hook and line gear by Cuban research personnel.

At each location, I attempted to purchase 60-70 fish of each sex, with lengths spanning the anticipated size range of 200-650mm fork length (FL). Due to accessibility to fish markets, ability for fishers to get on the water, and collection gear, sex-specific size bins were not always filled.

For each specimen, fork length (FL) was measured to the nearest millimeter

(mm), and weighed to the nearest gram. Otoliths (sagittae) were extracted after removing part of the cranium. After extraction, otoliths were rinsed with water, wiped dry with a Kimwipe™, and stored dry in labeled envelopes for processing.

The sex and reproductive state was assessed by visual examination of gonads on all fish. The varying lengths of time between capture and processing, generally without storing the fish on ice, precluded a more detailed analysis of reproductive status. This was true for all 3 regions that were sampled. Dorsal fin clips were

11 collected from all fish for genetic species identification as Albula vulpes, Albula goreensis, or a hybrid. Fin clips were stored in a piece of filter paper inside a labeled coin envelope and dried for 24 hours to prevent degradation of the genetic material. All genetic samples were sent to Dr. Elizabeth Wallace at Florida Fish and Wildlife Research Institute (FWRI) for analysis.

Otolith Processing

In the laboratory, each otolith was weighed and prepared for sectioning by embedding it in an epoxy mix of Aradur™ and Araldite™. Left sagittae were cut into three 300-500 μm thick transverse sections through the centrum (Figure 2) using a Buehler Isomet low-speed saw. If the left otolith was broken or missing the right otolith was used. Sections were individually mounted to glass microscope slides with ShandonMount.

Figure 2: Micrograph of a transverse section from an 8-year-old (350mm) bonefish, Albula goreensis viewed with transmitted light source.

Sections were read by three independent readers (myself, and two readers from the FWC Age and Growth Laboratory) by a dissecting microscope using reflected or transmitted light depending on which gave annuli a clearer image. Of the 3 sections, the section that gave the clearest image of annuli was the section used for aging. Otoliths that received different ages were reexamined and if disagreements were not reconciled after reexamination, the fish was excluded from the analysis.

Data Analysis

Data were analyzed using the Statistical Package R a free software environment for computing and graphics. Fish that did not receive a genetic identification, were unable to be measured accurately, or had broken or unreadable otoliths were excluded from the aging analysis.

Length and age frequency distributions were tested for significant differences in size and age with a two-sample Kolmogorov-Smirnov (K-S) test

(Neumann and Allen 2007).

A standard way to characterize age and growth patterns of fish is the von

Bertalanffy growth model (von Bertalanffy 1957). The equation for this growth

(K) (t- t0) model is Lt=L∞(1-e ), where L∞ is the asymptotic maximum length, K is the rate at which L∞ is achieved, t0 is the theoretical length at age 0. For this study fork length (FL) and age were used for both species of bonefish, Albula vulpes and

Albula goreensis to develop species specific von Bertalanffy (VB) growth equations. Previous studies (Crabtree 1996, Pfeiler et al. 2000, Adams 2008, Larkin

2011) also used FL for growth analyses. The VB growth model was fitted to sex- specific data sets for A. vulpes and pooled data for A. goreensis. Data were pooled for A. goreensis due to low sample sizes

RESULTS

Species Abundance, Distribution and Sex Ratio

A total of 218 bonefish were obtained in Cuba from November 2016-

January 2017 from fishers in Cuba. Discussions with the fishers indicated that they typically caught bonefish in gill nets deployed in near-coastal waters ranging from

0.5-2 meters deep. Gill nets were set with the intention of catching bonefish during the spawning migration.

Genetic analysis determined that 134 of the bonefish were A. vulpes, 59 were A. goreensis, and 7 were Albula vulpes x goreensis hybrids (E. Wallace, pers. comm.). The remaining 22 fish had degenerated genetic samples preventing valid identification, and thus were excluded from all analyses.

Most of the collections occurred in the northcentral region where fish markets were most accessible. Of the 131 genetically identifiable fish obtained from northern fish markets 67% were identified as A. vulpes, 29 % as A. goreensis, and 4% as interspecific hybrids (Table 1). There was evidence of species separation in schools during the spawning season. Bonefish were collected on two consecutive days during the early winter 2016 spawning season from two fish markets located

15 km apart. Fish caught near and marketed at Playa Nazabal were 100% A. goreensis, and 100% A. vulpes at Juan Francisco (Figure 3). Bonefish were collected from these sites on later dates, however mixed species schools were

15 observed, having A. vulpes, A. goreensis, and hybrids being caught from the same location in a given day.

Figure 3: Detailed map of the fishing village locations of Playa Nazabal and Juan Francisco.

Table 1: Summary of number of Albula spp. obtained from each sampling region in Cuba collected from 2016-2017.

Almost all fish had developing gonads, indicating their readiness to spawn in coming months. There was an unequal representation of males and females for both A. vulpes and A. goreensis. A. vulpes catches were primarily male, comprising

74% of the sexed fish that were obtained. In contrast, A. goreensis consisted of

77% females. There were 32 females, 88 males, 2 immature Albula vulpes, and 12 were unsexed. There were 42 females, 12 males, 1 immature Albula goreensis, and

4 were unsexed. Unsexed fish had either been gutted by fishers prior to processing or had decomposed past the point of identification of gonads.

Bonefish Size Distribution

A. vulpes ranged from 187-530mm FL with a modal size of 301-350mm FL and a mean size of 358mm FL (Table 2). Females were significantly larger than males (p=7.674-06) (Figure 4). In comparison, A. goreensis had a smaller maximum length (410mm FL), but a similar modal size of 301-350mm FL, and a mean size of

310mm FL (Table 2). All A. goreensis greater than 350mm FL were female (Figure

5), but there was not a significant difference in length frequency distributions by sex (K-S test, p=0.424). A total of 7 hybrids were obtained from the two sampling locations San Felipe and Playa Nazabal. Hybrids ranged in size from 210-351mm

FL and had a mean size of 309mm FL. Females were larger than males in both species. A. vulpes (pooled data) was found to grow significantly larger than A. goreensis with a p-value of 9.3-06.

Table 2: Summary of sample size, age range, and size range for all species of bonefish collected in Cuba from 2016-2017.

Figure 4: Length frequency distribution of A. vulpes collected in Cuba 2016-2017. Male n=87, and female n=30.

Figure 5: Length frequency distribution of A. goreensis collected in Cuba 2016- 2017. Male n=12, and female n=42

Bonefish Sex Distribution and Gonadal Development

Visual examination of the gonads of each fish showed that almost all fishes could be characterized as females with developing ovaries or males with large testes. With exception of 2 individuals all fish sampled 210mm FL and larger were determined to be reproductively mature. The time between capture, transport to market in the northcentral region, and examination precluded histological analysis of oocyte sizes or production of sperm. Most of the fish from the San Felipe Island chain, and Zapata Swamp were processed by Cuba researchers, who did not have the ability to complete a histological analysis, due to lack of equipment. Fish that did not have sex assessed either were missing all internal organs due to fishers gutting them, or had decomposed past the point of identification. Collected during their spawning season, females possessed ripe ovaries at small sizes (<300mm) and at a young age, with the smallest mature 1 year old A. vulpes female at 231mm FL.

All fishes were collected during the winter months, which is the typical spawning season for these species in the Bahamas and Caribbean.

Bonefish Age Distribution

Based on annuli counts, A. vulpes males were younger and smaller than females, and ranged in age from less than a year to 8 years old. A. goreensis ranged in age from 1-9 years old. The modal age for A. vulpes was 3 years old for males and 5 years old for females (Figure 6). A K-S test was performed for A. vulpes comparing age distributions between sexes. Females were observed at significantly

21 older ages than males with a p-value of 5.478-05. By comparison A. goreensis also had older females and younger males (Figure 7). The modal age for male A. goreensis was 1 year and 2 years old for females. A. goreensis males were not observed above the age of 5. Despite the age ranges being very similar, A. goreensis had the oldest fish from this study with a 350mm FL female aged at 9 years old. There were no significant differences in age distributions between species.

Figure 6: Age frequency distribution of Albula vulpes collected in Cuba 2016-2017 Male: n=87, Female: n=30

Figure 7: Age frequency distribution of Albula goreensis collected in Cuba 2016- 2017 Male: n=12, Female: n=42

Bonefish Age and Growth Curves

Otolith ageing data indicate that A. vulpes and A. goreensis grow at different rates and reach different maximum sizes. A. vulpes collections included 88 males and 32 females, allowing examination of growth trajectories of each sex.

Because only 12 male A. goreensis were collected, both sexes were pooled to characterize the growth of the species. A. vulpes females grew faster and reached larger sizes than males. A. vulpes males reached a calculated L∞ of 387mm FL, reached at 4-5 years of age (Table 3 and Figure 8). A. vulpes females reached a calculated L∞ at the same age, but at 50mm FL larger (Table 3 and Figure 8). Male and female curves were similar in the growth coefficient (K), however in comparison they reached different maximum theoretical sizes. Female A. vulpes lacked younger smaller fish to help define the initial rapid growth. Comparatively young A. vulpes males were abundant at smaller sizes helping to define the initial rapid growth but were lacking in the older larger fish that varied from the calculated maximum FL.

Both male and female theoretical maximum length (L∞) for A. vulpes were calculated to be larger than that of pooled data for A. goreensis (Table 3). VB curves were calculated for A. goreensis with pooled data because there was an insufficient sample size for males (n=12) to calculate sex-specific growth curves. A. goreensis did not have a rapid period of growth from what was calculated between ages 1 and 9 (Figure 9). Despite a sex specific curve not being able to be derived for A. goreensis, it was evident in the scatter plot (Figure 9) that females drove the

24 latter part of the curve, where there was a lack of males after age 5. A. vulpes and

A. goreensis were very similar in size at age 1, however A. vulpes continued to grow to larger sizes, conversely A. goreensis had limited further growth (Figure

10). A. vulpes has a more rapid growth at younger ages, while A. goreensis is slow growing not reaching a large size.

Collecting juveniles for both species would help define the initial growth rate of young-of-year fish, however sampling limitations made it feasible to only obtain adult bonefishes. To get a better estimate of initial growth more juveniles and young of year fish would be needed and to be aged to the day, not to the year.

Figure 8: Observed FL at age and von Bertalanffy growth curve for A. vulpes males and females.

Figure 9: Observed length at age and von Bertalanffy growth curve for A. goreensis collected in Cuba 2016-2017. L= Length, t=age in years

Figure 10: Predicted FL at age of A. vulpes and A. goreensis calculated from VB growth equations.

DISCUSSION

A. vulpes of the Florida Keys have been determined to grow faster and larger than those inhabiting the Caribbean and the Bahamas (Crabtree et al. 1996,

Adams et al. 2008). This thesis characterizes the growth rates and age at reproductive maturity of both bonefish species, Albula vulpes and Albula goreensis in Cuba to directly compare growth and reproductive maturity between the two species. A. vulpes were found to grow slower and to a smaller maximum size in

Cuba than in the Florida Keys. Reproductive maturity of A. vulpes was observed at a younger age and at a smaller size in Cuba than A. vulpes in the Florida. Keys. For the newly described A. goreensis, data collected provides a baseline for growth that had a smaller maximum size than A. vulpes found in the same region in Cuba.

The majority of fish examined in this study were obtained from commercial and subsistence gill net fishers at several fishing villages along the Cuban coastline.

Gill netting effort is concentrated during the fall/winter spawning season because fish are easier to target as they swim in large schools along predictable migratory pathways. Since gill nets are efficient collectors only for certain size ranges of fish, small and large fish may be underrepresented in the data. Nevertheless, age/growth curves can be calculated from the collected data, and the reproductive status of the captured specimens provides information on the age of reproductive maturation.

Over 65% of the 218 bonefish collected were identified as A. vulpes (Table 2).

Fishers targeting bonefish primarily set gill nets in near-coastal waters adjacent to

29 channels and on flats in relatively shallow water (0.5-2m). A. vulpes spends majority of their non-reproductive time on shallow flats moving into deeper water on ebbing tides or for thermal refuge in times of extreme heat and cold (Humston et al. 2005), while A. goreensis tends to occur in slightly offshore and in deeper channels (Wallace and Tringali 2016). In both north and south coast fish markets,

A. vulpes contributed to 67%-69% of the bonefish caught, however A. goreensis was not observed in the Zapata Swamp samples. All bonefish caught by researchers in the Zapata Swamp were A. vulpes.

A. vulpes and A. goreensis on the northcentral coast of Cuba displayed possible species segregated schooling behavior during the November spawning season. Bonefish were obtained on two consecutive days from two villages on the northcentral coast of Cuba: Playa Nazabal and Juan Francisco. Fish from Playa

Nazabal were 100% A. goreensis and Juan Francisco fish were 100% A. vulpes.

Conversely, bonefish collected at a later date from Playa Nazabal did not display species segregation, having A. vulpes, A. goreensis, and hybrids. All bonefish of both species had large, well-developed gonads, suggesting they were captured shortly prior to spawning. Whether both species use the same pre-spawning aggregation site is unknown, but the presence of a small number (n=7) of interspecific hybrids indicate that at least some species mixing does occasionally occur. Although both species were captured in southwest Cuba, fish from a wide region were brought to a single market, so it was not possible to determine if species segregation occurs in that region.

A. vulpes in Cuba, grew more slowly and reached smaller sizes at any given age than A. vulpes from the Florida Keys (Crabtree et al. 1996). The growth trajectory of Cuban fish was more similar to that observed from the Bahamas

(Figure 11; Adams et al. 2008).

Larkin (2011) expanded on Crabtree’s study collecting samples outside of the previous size range. More young-of-year fish were aged, having 118 of the bonefish under 300mm FL. Larkin found new maximum age (21 years old) is larger than previously observed by Crabtree (19 years old). Larkin filled in missing size classes collecting younger and older year-classes by using a variety of gears to capture fish.

Figure 11: Von Bertalanffy growth curves calculated for A. vulpes populations in the Florida Keys, the Bahamas, and Cuba. (Crabtree et al. 1996, Adams et al. 2008).

There are several explanations that can explain why Cuban bonefish grow to smaller sizes than those of the Florida Keys. Gear bias selecting for smaller fish may be an artifact of obtaining fish from a gill net fishery. Gill net mesh sizes ranged from 40-70 millimeters, which could have excluded larger fish from catches. Although gill nets are very efficient at catching many types of fish within a specific size range, bonefish have small conical snouts that can easily tangle in the small mesh of seine nets (personal observation). Even if there is gear bias for these samples, the VB curves for bonefish in the 3 sampling regions in Cuba show that

32 these fish grow more slowly and reach smaller sizes for any given age than do bonefish in the Florida Keys. Despite the smaller sized bonefish observed throughout the 3 regions sampled, however, there have been reports of much larger bonefish occurring in portions of Cuba that are more protected and isolated than the regions that were sampled for this thesis. Bonefish were reported up to 700 mm FL in the western portion of Cuba (J. Angulo and Z. Martinez, 2017).

The observation of larger bonefish in protected areas of Cuba suggest a second potential reason for the differential growth rates among regions: intense local fisheries harvest pressure can alter the demographic age structure of the fished populations, relative to unfished populations. Harvest pressure for bonefish in Cuba varies between regions. Along the north coast there is a considerable gill net fishery for bonefish, which is intensified during the fall/winter spawning season. It is easier to target schools of migrating bonefish to pre-spawning aggregations. Harvest of aggregating species enables fishers to catch a large amount of fish in a very short period of time. Aggregating species have been fished out to depletion through harvest with various types of nets, such as various snapper, grouper, and cod species (Rose 1993, Claro et al. 2001, Sadovy 2004). Through the continual harvest of aggregating species in Egypt over 8 years, total catches and mean sizes declined

(Salem 1999).

Fish along the north coast of Cuba may be harvested at a high enough rate that prevents individuals to reach larger sizes. The dominant target for gillnetters in the Tarawa Lagoon in the Pacific Ocean, bonefish (Albula glossodonta) were

33 fished for heavily with gillnets during their spawning season. Bonefish displayed significant declines in catches over two decades. Female bonefish having a larger mean size, were selectively depleted during this time of intense harvest (Beets

2001). Shifts in sex ratios with a depletion of females can be indicate that populations are under stress from overharvesting (Sadovy 1996). Sex ratios observed in this study for A. vulpes were heavily male making up roughly 75% of the fish collected. This depressed sex ratio of females could indicate that populations of A. vulpes are under harvesting stress and are in need of immediate attention to managers.

This intense fishing pressure on pre-spawning bonefish suggest that fisheries induced evolution (FIE) may impact the growth dynamics of Cuban populations. FIE has been observed in many species including Atlantic cod (Gadus morhua). Studies have shown that FIE can cause single traits such as age/size at maturity and growth rates to evolve with rapid size selective harvesting over a couple generations (Conover and Munch 2002, Olsen et al. 2004, Walsh et al.

2006). However, FIE implies that populations are relatively isolated genetically, retaining the influenced traits within the population. Larval dispersal models for various snapper (Lutjanidae) species in Cuba determined that spawning aggregations on the northcentral coast resulted in a high proportion of self- recruitment, and were also the sources of larvae to other regions such as northwest

Cuba and the Bahamas (Paris et al. 2016). Snapper larvae may persist in the plankton as larvae for a maximum of 40 days (Denit & Sponaugle 2004), a shorter

34 larval duration than leptocephalus bonefish. Although Paris et al. (2016) did not address the input of larvae from other regions of the Caribbean into Cuba, an ongoing larval bonefish transport study suggests the potential for significant connectivity with Caribbean habitats (M. Roffer, pers. comm).

A third possible hypothesis for the variation in growth rates between the

Florida Keys, Cuba, and the Bahamas is potential variations in habitat productivity and prey availability (Adams et al. 2008). This hypothesis suggests the terrestrial nutrient inputs from rivers and streams into some coastal habitats may increase productivity of that system, as compared to regions with lower levels of nutrient supply. These variations in nutrient supply can potentially contribute to differences in the species composition and abundance of their prey base, resulting in varying growth rates and other biological parameters. A similar reduction in prey base may also arise from intensive fishing pressure on prey. In Cuba, the combination of intense fishing for penaeid shrimp and the damming of rivers for water conservation have resulted in a sharp drop in shrimp landings (Baisre & Arboleya

2006), and the reduction of a dominant component of the prey base for bonefish along the southern coast of Cuba and bonefish in the San Felipe Island chain.

Larkin (2011) developed a biphasic growth curve for A. vulpes in the

Florida Keys (Figure 12), determining fish reached an initial asymptote around

400mm FL achieving a length that allowed for a dietary shift. A. vulpes switched from feeding on penaeid shrimp while at sizes under 440mm FL to feeding on larger prey such as toadfish (Opsanus beta), xanthid crabs, and Callinectes spp.

(Crabtree et al. 1998). The variation in trophic productivity of ecosystems may be a main factor into growth variation, however a more detailed investigation of the trophic productivity for each ecosystem would need to occur for this to be linked with growth of bonefish.

Figure 12: Predicted biphasic growth curve for bonefish in FL Keys developed by Larkin (2011).

Finally, a reduction in growth rate and maximum size may be associated with differential allocation of resources to reproduction and growth. Different populations of a single fish species may have different reproductive behaviors that can alter other biological traits. Tarpon (Megalops atlanticus) that appear to spawn throughout the year in Costa Rica and other tropical habitats reach smaller

36 maximum adult sizes than tarpon in Florida, which have a more limited spawning season (Crabtree et al. 1997b). This concept of variability in energetics of egg production and spawning may be applied to bonefish. Bonefish in the Florida Keys displayed seasonal gonad development activity peaking during the months of

November through May (Crabtree et al. 1997a), while bonefish in the Bahamas displayed behaviors that indicated spawning between the months of October and

May (Danylchuk et al. 2011) staying mostly consistent with the Florida Keys bonefish. Larval and juvenile data from Mojica et al. (1995) suggests spawning may occur nearly year-round, however there were observed peaks during periods of elevated spawning. Despite data pointing to year-round spawning, there are still peak spawning pulses in the winter and spring seasons. To determine if energy allocated towards reproduction is the cause of varying maximum sizes of bonefish, data needs to be collected to display bonefish from specific regions are spawning multiple times per year.

Previously bonefish in the FL Keys have been observed to reach reproductive maturity between 400-480mm FL, with males reaching reproductive maturity at 3.6 years old and females at 4.2 years old (Crabtree et al. 1997). The youngest fish to reach reproductive maturity from the Crabtree study was a 2-year old female. In comparison, a female bonefish in Little Cayman was sexually mature at 342mm FL (Adams et al. 2008). The present study found that female A. vulpes in developed gonads as early as age 1 and at 231mm FL. All fish larger than 245 mm

FL and at least 2 years old were reproductively mature. This is younger and smaller

37 than previously observed throughout the Caribbean and Florida. Because of maturation at such a small size and young age, bonefish may be allocating more energy for reproduction rather than somatic growth.

As with geographic differences in the growth rates of bonefish, the driving forces for the different ages of maturation of A. vulpes in Cuba, the Florida Keys, the Bahamas, and Caribbean have yet to be determined. Examination of growth and reproductive patters in other Caribbean habitats, and studies on genetic linkages among island populations, may help ascertain the factors that influence these life history parameters.

Cuban specimens of A. goreensis provide the first data on age, growth, and reproduction of this newly-described species. A. goreensis in Cuba reached an asymptote around the same age (5-6 years old) but at a much smaller size (347mm

FL) than A. vulpes (Table 3). All fish that were examined above 250mm FL were reproductively mature, even fish as young as age 1.

spp.

Albula

number collected. number of fish

and and

(mm)

ertalanffy growth parameters for growth parameters ertalanffy

von B

, K= growth coefficient, growth , K=

(mm)

past publicationpast

length

fork fork

of current study and of current

estimated maximum estimated

∞

: Summary

Table 3 Table

As found by Crabtree (1996), A. vulpes displayed sexual dimorphism finding that females grow significantly larger than males. There was not a large enough sample size to run sex specific growth curves for A. goreensis, however female A. goreensis did grow to larger sizes and older ages than males. The VB growth curve generated for A. goreensis was with pooled data from males and females.

This study on bonefish in Cuban habitats identified differences in growth and maximum size between the major fishery species, Albula vulpes and the cryptic

Albula goreensis, with A. vulpes growing larger than A. goreensis. Both species of bonefish in Cuba are reproductively mature at much smaller sizes and younger ages than A. vulpes in the Florida Keys. An investigation of the age and growth of A. goreensis would give definitive insights to if there are major growth differences between these two regions and should be assessed in the future. As yet, no definitive mechanisms for differential growth and maturation rates of fish in populations in these nearby regions have been determined. Investigations assessing age at maturation and spawning frequency of bonefish in different regions, genetic connectivity among populations and geographically variable trophic productivity may give more detailed insights for the differences in bonefish biology observed between Cuba, the Florida Keys, and other islands in the Bahamas and Caribbean.

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