University of Florida Thesis Or Dissertation Formatting

RISK-BASED APPROACH TO EVALUATE ALLIGATOR GAR ATRACTOSTEUS SPATULA AQUACULTURE IN FLORIDA

LAUREN N. LAPHAM

A THESIS PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE

UNIVERSITY OF FLORIDA

2019

To my family

ACKNOWLEDGMENTS

I thank the members of my supervisory committee, Drs. Jeff Hill, Quenton

Tuckett, and Josh Patterson, for their support and guidance with my research, scientific writing, and professional development. Thanks also to my professors for their guidance and education in the classroom.

I also thank those who assisted in my research, the project team and stakeholders from the Florida Aquaculture Association, Florida Tropical Fish Farms

Association, Florida Department of Agriculture and Consumer Sciences, Florida Fish and Wildlife Conservation Commission, U.S. Fish and Wildlife Service, Oklahoma

Division of Wildlife Conservation, University of Florida, and U.S. Geological Survey, who were essential to the completion of this research. I thank the project team, Jeff Hill,

Quenton Tuckett, Josh Patterson, and Allison Durland Donahou, for their involvement and input. In addition, I thank my family and friends for their continued support and encouragement. I am particularly grateful to my parents and grandparents for their support of my education.

Funding for this project came from the Florida Fish and Wildlife Conservation

Commission (FWC). The UF/IFAS Tropical Aquaculture Laboratory, director Craig

Watson, provided facilities for the stakeholder panel meeting. I especially thank the grant management team, Kristin Summers, Sarah Funk, and Kelly Gestring (FWC); also for assistance, David Boozer of the Florida Tropical Fish Farms Association, Tiffany

Conner of the Florida Aquaculture Association, and Chelsea Crandall (UF). Finally, I am grateful for and thank the faculty, staff, and students at the UF/IFAS Tropical

Aquaculture Laboratory for their support.

TABLE OF CONTENTS

page

ACKNOWLEDGMENTS ...... 4

LIST OF TABLES ...... 7

LIST OF FIGURES ...... 8

LIST OF ABBREVIATIONS ...... 9

ABSTRACT ...... 10

CHAPTER

1 INTRODUCTION ...... 12

2 METHODS ...... 16

Biological Synopsis ...... 16 Risk Screening ...... 17 Generic Analysis ...... 21

3 RESULTS ...... 29

Biological Synopsis ...... 29 Alligator Gar Atractosteus spatula Biological Synopsis ...... 34 Classification ...... 34 Distribution ...... 43 Biology ...... 58 Control ...... 65 Potential Florida Distribution ...... 66 Potential Impact ...... 73 Risk Screening ...... 84 Generic Analysis ...... 87 Stakeholder Workshop and Generic Analysis ...... 87 Stakeholder Workshop Evaluation ...... 94

4 DISCUSSION ...... 114

Data Gaps and Research Recommendations ...... 118 Management Implications and Risk Mitigation ...... 118

APPENDIX

A STAKEHOLDER GENERIC ANALYSIS WORKSHEET ...... 122

B WORKSHOP EVALUATION FORM ...... 126

LIST OF REFERENCES ...... 128

BIOGRAPHICAL SKETCH ...... 140

LIST OF TABLES

Table page

2-1 Stakeholder panel members’ affiliation and experience. Panel members were not compensated or provided with travel funds by the project team for their participation ...... 26

2-2 Project team, affiliations, and title/expertise ...... 27

2-3 Stakeholder presentations, presenters, and affiliations ...... 28

3-1 FISK scores for three assessors of Alligator Gar aquaculture in Florida (mean = 4; Δ = 2). The score is the overall score of each assessor, with the overall scores the sum of the scores in each section (Biogeography/Historical (1.01 to 3.05) and Biology and Ecology (3.01 to 8.05)). Scores <1 indicate low risk, scores ≥ 1 and ≤10.25 indicate medium risk ...... 96

3-2 FISK version 2 assessment for Alligator Gar for Florida. The Q ID column corresponds to question identification codes in FISK. Answer codes are N = no, Y = yes, and ? = don’t know and are separated to show answers, justification, and certainty of the two independent assessors. Certainty codes are 1 = very uncertain, 2 = moderately uncertain, 3 = moderately certain, and 4 = very certain ...... 98

3-3 Breakout groups and overall risk assessment results. Oponions different within groups where there are multiple risk ratings or certainty values. The composition of breakout groups differed for the two sections (establishment and consequences). Risk levels are H = High, M = Medium, and L = Low. Theoverall risk of establishment is the lower of the four ratings and the overall risk of consequences is the highest rating between environmental and economic (unless both are low, then social/political). The ORP is the average of establishment and consequences, rounded up. Certainty levels are as follows: VU = very uncertain, RU = reasonably uncertain, MC = moderately certain, RC = reasonably certain, and VC = very certain ...... 112

3-4 Results of the evaluation of the stakeholder risk assessment workshop. All participation was anonymous, with seven attendees providing answers following the completion of the workshop ...... 113

LIST OF FIGURES

Figure page

3-1 Alligator Gar...... 34

3-2 Juvenile Alligator Gar of normal and leucistic coloration ...... 37

3-3 Juvenile Alligator Gar ...... 38

3-4 Adult Alligator Gar ...... 38

3-5 Adult world record Alligator Gar, 2.6 m, 148 kg ...... 39

3-6 Platinum (or snow) Alligator Gar ...... 41

3-7 Map of North American range occurrences of Alligator Gar, including the native range ...... 44

3-8 Known distribution of established Alligator Gar populations in the United States ...... 44

3-9 Map of sustaining, historic, remanent, and stocked populations of Alligator Gar throughout their native range ...... 45

3-10 Coloration of juvenile Alligator Gar ...... 62

3-11 Alligator Gar CLIMATCH source map ...... 68

3-12 Alligator Gar CLIMATCH target map in Florida...... 69

3-13 RAMP map of climate match for Alligator Gar in the United States ...... 69

3-14 RAMP interpolated grid for A. spatula climate matching ...... 70

3-15 Bar chart of Alligator Gar literature produced from 1990-2018 ...... 81

3-16 Distributions of certainty percentage for the answers to 49 questions of the FISK risk screening ...... 97

3-17 Distributions of FISK risk category scores with the average and standard deviation ...... 111

4-1 FISK scores of five ornamental or food fish species compared to Alligator Gar ...... 121

4-2 Distribution of Alligator Gar in Mexico ...... 121

LIST OF ABBREVIATIONS

ANSTF Aquatic Nuisance Species Task Force

BMP Best Management Practices

DPH Days Post Hatch

FISK Fish Invasiveness Screening Kit

FWC Florida Fish and Wildlife Conservation Commission

Abstract of Thesis Presented to the Graduate School of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Master of Science

RISK-BASED APPROACH TO EVALUATE ALLIGATOR GAR ATRACTOSTEUS SPATULA AQUACULTURE IN FLORIDA

Lauren N. Lapham

August 2019

Chair: Jeffrey E. Hill Major: Fisheries and Aquatic Sciences

Alligator Gar Atractosteus spatula is native to North America and has declined throughout much of its range, including the Florida panhandle. Few data exist for

Alligator Gar in Florida; therefore, the Florida Fish and Wildlife Conservation

Commission implemented a harvest closure in 2006, making it illegal to take or possess

Alligator Gar without a permit. There is interest in Florida to culture Alligator Gar for food and out-of-state ornamental sale, neither of which are currently permitted. Although

Alligator Gar is native, there is concern for invasiveness in areas of Florida outside of the native range if commercial aquaculture were permitted. Before making decisions concerning commercial culture, it is prudent to evaluate the risks of establishment and impact in Florida. Invasiveness risk was assessed through an extensive literature review and biological synopsis, risk screens, and a stakeholder-inclusive qualitative risk assessment. The biological synopsis provided considerable information on invasive potential and data gaps. The Fish Invasiveness Screening Kit (FISK) assessments provided a preliminary risk estimate of non-invasive. An expert stakeholder panel determined that the risk of Alligator Gar aquaculture was of moderate concern. The overall risk of aquaculture was evaluated at the low end of medium and supported by a

federal risk screen. Discussion of risk mitigation concluded that aquaculture best management practices are acceptable to reduce risks. Research and management recommendations arising from the risk-based process are available for agencies and industry to support decision making regarding permitting, restricting, or prohibiting aquaculture of Alligator Gar and facilitate the development of risk management options.

CHAPTER 1 INTRODUCTION

Culture of non-native fish can be problematic because escape can result in establishment and spread of non-native populations, which may cause negative impacts such as habitat modification or native species decline (Cook et al. 2008; Hill 2008;

Cucherousset and Olden 2011). Yet, some of the most important aquaculture species worldwide are cultured outside of their native range (e.g. carps and tilapia; Gozlan et al.

2010; Fitzsimmons et al. 2011). Non-native species dominate the largest segments of

Florida aquaculture, especially tropical aquarium fish (40% of Florida aquaculture value in 2012; USDA-NASS 2013) and are important components of various commodity groups. The use of native species in aquaculture could avoid negative impacts from the introduction of non-native species and is important to consider (Ross et al. 2008).

Despite frequent calls in the literature, there are issues to consider with the use of native fish in aquaculture (Ross et al. 2008; Cruz‐Casallas 2011; Saint-Paul 2017).

Native fish which escape from aquaculture may affect wild populations through interbreeding, potentially reducing fitness of wild stocks (Weir and Grant 2005).

Therefore, cultured organisms not intended for local stocking, whether native or non- native, are usually subject to regulations intended to reduce escape (FDACS 2016).

Risk analysis is an approach that can be used in aquaculture management to identify hazards and resulting risks, and to effectively manage risks arising from potential introduction of cultured organisms (Hardin and Hill 2012; Hill and Lawson 2015).

Interest in commercial culture of Alligator Gar in Florida as an ornamental and food fish is increasing. Methodology for culturing Alligator Gar is well documented, because the species is cultured in federal hatcheries (Private John Allen National Fish

Hatchery; Tishomingo National Fish Hatchery) for stock enhancement, and at universities for research. Alligator Gar are easily maintained in captivity, spawn readily under hatchery conditions, tolerate of a wide range of water quality conditions, and can be raised entirely on artificial feed (Weed 1923; Mendoza et al. 2002a; Mendoza et al.

2002b; Clay et al. 2009). National and international ornamental markets and regional food markets currently exist (Suttkus 1963; Buckmeier 2008; DiBenedetto 2009; Zullo

2009; Ichien 2011). However, the species is currently unavailable for commercial culture in Florida due to the fishing ban which prohibits take or possession without a scientific collectors’ permit (FWC 2019).

The Alligator Gar Atractosteus spatula is native to the western panhandle of

Florida, historically found west of the Econfina River (Lee et al. 1980; Boschung and

Mayden 2004; Froese and Pauly 2018). In recognition of population declines throughout its native range and reduced catch in Florida, a harvest closure of Alligator Gar was implemented in 2006 by the Florida Fish and Wildlife Conservation Commission (FWC

2019). The decline in Alligator Gar populations throughout their native range has been attributed primarily to anthropogenic impacts including: habitat loss from stream channelization, isolation of floodplains by levee construction and subsequent development, and overharvesting (Etnier and Starnes 1993; Mettee et al. 1996).

Alligator Gar was historically targeted for eradication programs throughout their native range because agencies considered Alligator Gar to be ‘trash fish’ and a nuisance species, negatively impacting desired game fish (Scarnecchia 1992; Schultz 2004).

More recently, biologists and anglers consider Alligator Gar to be an integral component

of the native ecosystem as well as a valuable game and food fish (Scarnecchia 1992;

Fuller 2019).

The FWC determined that a risk analysis process would be necessary to evaluate the potential for legal commercial culture of Alligator Gar in Florida. With the ultimate goal of providing information for management decisions, an evaluation of

Alligator Gar aquaculture in Florida was completed under an expanded risk assessment protocol. Risk assessment tools have been used extensively in Florida to support agency management decisions (e.g. Arapaima Arapaima gigas (Hill and Lawson 2015);

Barramundi Perch Lates calcarifer (Hardin and Hill 2012); Grass Carp

Ctenopharyngodon idella (Zajicek et al. 2009); tilapia (Hill 2017); and marine ornamentals (Zajicek et al. 2009)).

The risk assessment process for Alligator Gar aquaculture in Florida utilized an established process consisting of three components: (1) a review of Alligator Gar literature, (2) an internationally recognized rapid risk screen, and (3) a comprehensive stakeholder meeting to perform a qualitative assessment of risk using a U.S. federal methodology as framework. Of concern were potential risks associated with the introduction of captive Alligator Gar into the environment (1) outside the native range in north and peninsular Florida where they might establish, spread, and cause impacts and (2) in the native range in the panhandle where they might negatively interact with wild populations. The Fish Invasiveness Screening Kit (FISK) v2 (Lawson et al. 2013) provided an initial estimate of risk and hazard analysis. Expert stakeholders completed a comprehensive risk assessment using the U.S. Federal Generic Analysis approach

(ANSTF 1996). These components were used to complete the risk assessment

process, identify data gaps, compile and analyze data, and provide research and management recommendations.

METHODS

Biological Synopsis

The biological synopsis is a compilation of Alligator Gar literature including information on taxonomy, biology, and ecology, along with information that is useful for the risk assessment process. The biological synopsis identifies data gaps and utilizes information related to risk assessment, including factors indicative of invasion potential.

These factors include invasion history and establishment, climate matching, and documented impacts. These elements are widely considered to be useful for determining invasion potential (Kolar and Lodge 2002; Daehler et al. 2004; Marchetti et al. 2004).

This component followed the standardized format used in previous evaluations of non-native fishes (e.g. Arapaima, Barramundi, and Damselfish). Information for the literature review was derived from primary literature, computer databases (Google

Scholar, Web of Science), invasive species database searches (USGS Nonindigenous

Aquatic Species database), and fish/aquatic life/distribution databases. Search terms utilized during the literature review included the common names as well as current and former scientific names for Alligator Gar (e.g. Lepisosteus spatula) and terminology related to the various topics such as “Alligator Gar spawning period” and “Alligator Gar aquaculture.” Literature was further analyzed using reference backtracking, citation lists, perusal of investigators’ libraries, discussions with colleagues, hobbyist literature, and online sources to supplement and fill relevant synopsis sections.

The biological synopsis provided information necessary for the risk screenings, additional data for management agencies, and elucidates data gaps and future research needs. Also included are sections where information is synthesized by the author to

discuss potential range and impacts in the risk assessment area. The biological synopsis was included in stakeholder materials utilized for the completion of the qualitative Generic Analysis and risk screens.

Risk Screening

The risk screen was completed for the assessment of Alligator Gar aquaculture in Florida using the Fish Invasiveness Screening Kit version 2 (FISK v 2; Lawson et al.

2013). The FISK is an internationally recognized rapid risk screening tool used to provide an initial estimate of risk, identify hazards, and determine if further assessment is needed (Copp et al. 2005). The FISK is a semiquantitative tool that consists of questions relating to biogeography/history and biology/ecology, resulting in an overall risk score that is calibrated into three levels of potential risk, low, medium, and high

(Lawson et al. 2013). Increasing overall scores equate to increasing risks of establishment and impacts for non-native freshwater fishes.

The FISK risk screening tool was developed from the Australian Weed Risk

Assessment model (Pheloung et al. 1999). The FISK tool was developed to assess potential invasiveness of non-native freshwater fish in England and Wales, a temperate zone climate (Copp et al. 2005, 2009; Lawson et al. 2013). In response to climate limitations presented by FISK v1, the FISK v2 was developed to increase its utility in warmer climates (Lawson et al. 2013). FISK questions and guidance were reviewed and revised to extend climatic applicability to additional climatic regions (e.g. tropical and subtropical environments; Lawson et al. 2013). The FISK has been applied in 35 risk assessment areas in 45 countries, with 1,973 FISK assessments completed by 70 + experts on 372 taxa (Vilizzi et al. 2019). There are at least five published applications for Florida, or that include Florida in the risk assessment area (Lawson et al. 2013 –

FISK v2; Lawson et al. 2015 – Florida FISK calibration; Hill et al. 2014 – Glofish FISK,

Hill et al. 2017 – Ornamentals in the United States; Hill and Lawson 2015 - Arapaima; see also Vilizzi et al. 2019).

For Florida, a FISK calibration threshold of 10.25 was calculated to distinguish between invasive and non-invasive species (Lawson et al. 2015). The calibrated threshold correctly classified 76% of invasive fishes and 88% of noninvasive fishes

(Lawson et al. 2015). In Florida, low risk scores are ≤ 0, medium risk scores are >0 to

10.25, and high scores are ≥10.25 (Lawson et al. 2015).

Risk assessment considers both potential invasiveness and the possible impacts of invasion, with FISK guidance defining high risk species as potentially invasive while low and medium scores are considered non-invasive. Low risk results principally mean there is little need for further assessment, and high risk means there is a need to assess further due to potential hazards presented. Medium risk is more complex because it can mean to assess the species further (potentially hazardous) or to stop assessment depending on the type of species and what factors added to or detracted from the overall score. Generally, low and medium species are unlikely to have moderate to severe impacts on the risk assessment area, while they have the potential to establish, the risks and impacts are lower. Should a low or medium risk species establish, the impacts are more likely be less noticeable or severe, while a high-risk species is more likely to have noticeable impacts upon establishment and is more likely to establish.

The FISK consists of 49 questions that result in an overall risk score, or sum, ranging from -11 to 53. The range of values for each question contributes to an overall score that is calibrated to three levels of potential risk, low, medium, and high (Lawson

et al. 2013). Higher overall scores equate to increasing risks of establishment and impacts for non-native freshwater fishes. The answers to FISK questions generate or modify the score of other questions. Specific questions relate to biology and ecological traits and can be answered by ‘yes’ or ‘no’, with justification allowing for explanations of data interpretation and references. Particular questions were developed to allow for the assessor’s judgement, such as questions regarding impacts of the species on the risk assessment area.

Assessor expertise and risk sensitivity are important factors to consider for the risk assessment process. The subjective assessors (screeners) are expected to follow the explanatory guides to each question and provide brief justification (e.g. citations) for responses and certainty associated with each answer. Justification provides transparency in the risk assessment process, facilitates discussion upon disagreement, and the opportunity for input as information or feedback is returned. Information and questions can be interpreted differently by assessors, with similar justifications associated with differing responses.

The FISK assessments were performed by three independent assessors to provide an estimate of risk (Table 2-2), with one additional project team member reviewing (Table 2-2) assessments to ensure quality control and identify potential errors for assessors to review. Multiple assessors result in a mean FISK score that is closer to the real risk value of the species (Copp et al. 2013). Training in risk assessment and related tools was completed prior to the execution of the FISK screenings, with two of the three assessors having numerous assessments and associated publications for

Florida. Assessor three completed two training sessions consisting of multi-day direct

training with the project director, several days of specific training, plus graduate level coursework in risk assessment.

Utilized in the risk screen is the climate matching program CLIMATCH

(Australian Bureau of Rural Sciences 2010). CLIMATCH is a peer reviewed, publicly available program that compares the similarity of climate stations in a source region and target region based on similarity index of 16 factors (precipitation, temperature). The software produces maps of the native region (source) and the risk assessment or target region, with source locations derived from literature. The risk assessment area for

Alligator Gar is Florida. The source map (Figure 3-11) includes blue and red points, with blue representing weather stations not used for the source map and red representing stations that were used. A climate 6 score is the acceptable similarity or measure of suitable climate between the source region and target region, with the algorithm of the system determining the climate distance between the source map and target area, with the level of the match determined by the closest standard score between input sites and target sites. A climate 6 score or higher is considered suitable climate for the organism.

The area of the red points is proportional to the number of match cells that this data point contributed to the target region. The target region map (Figure 3-12) was used to calculate the proportion of weather stations in Florida with a comparable similarity value

(climate 6 score). The target region map uses a scale of 1 to 10, ten being the highest match. The map illustrates the proportion of weather stations with climate 6 scores or higher matching the source region. The USFWS federal protocol was used to determine values for classifying CLIMATCH results for high (≥0.103), medium (0.005

derived from the Global Biodiversity Information Facility (www.gbif.org/en) and additional primary resources.

Individual overall scores and the mean scores of the three assessors for Alligator

Gar were compared to calibrated threshold for Florida (10.25) to provide an estimate of low, medium, or high risk for the risk assessment area (Florida). The FISK and

CLIMATCH results were used to ascertain research gaps and identify risks that may be important for decision making in Florida. Recommendations were made for management and future research needs to mitigate identified knowledge gaps.

Generic Analysis

The stakeholder workshop was assembled to complete a full risk assessment with a panel of experts to evaluate the risks of, and respond to questions of concern, for

Alligator Gar aquaculture in Florida. The qualitative risk assessment conducted was based on the federal Aquatic Nuisance Species Task Force (ANSTF 1996) methodology (hereafter ‘Generic Analysis’). Risks were evaluated for north Florida and peninsular Florida, regions outside of the native range of Alligator Gar in Florida, as well as within the native range (the western panhandle). Risks were evaluated to determine the risk potential of Alligator Gar establishment, spread, and impacts in peninsular

Florida and the potential and impacts of genetic interactions with cultured and wild

Alligator Gar in the panhandle.

A Generic Analysis of non-native species, or pathways of introduction, has been used at the federal and state level to evaluate the risks of non-native species and pathways (Hill and Zajicek 2007), including use by Florida agencies in the risk assessment area (Zajicek et al. 2009; Hardin and Hill 2012). The Generic Risk Analysis is a qualitative assessment of risk, resulting in an overall risk potential (ORP) of low,

medium, or high. For the Generic Analysis, a low risk rating means the organism is of little concern, or acceptable risk, while medium and high risk are considered

‘unacceptable risk’ and require some level of mitigation (ANSTF 1996).

The qualitative analysis is composed of multiple sections; (1) probability of introduction; (2) probability of establishment (i.e. colonization potential, spread potential), and (3) consequences of establishment (i.e. economic, environmental impacts). The sections consist of seven questions that each have an associated rating level, certainly, and justification. The first four questions address the probability of the organism being in the pathway, entry potential, colonization potential, and spread potential (probability of introduction and establishment). The last three questions address the impacts of establishment, specifically: economic impacts potential, environmental impacts potential, and perceived social and political impacts. Each question has a low, medium, and high rating for risk, and five associated certainty levels ranging from Very Uncertain, Reasonably Uncertain, Moderately Certain, Reasonably

Certain, to Very Certain with associated justifications to evaluate invasive potential and establishment impacts. Certainty, the level of confidence associated with a response, levels can change as data becomes available and reflects the assessors risk tolerance and experience with risk assessment.

To determine the overall risk of introduction and establishment, the lowest rating of the four questions is selected. The lowest rating is selected as a conservative measure, as each of the elements must occur (conditional probability) for an organism to establish. The overall risk rating for impacts of establishment is determined by selecting the highest rating between environmental and economic impacts. If both

environmental and economic impacts are rated low, the social/political ranking will be used to determine the overall impacts of establishment. The Overall Risk Potential

(ORP) is the conservative average (rounded up) of the risk of introduction and establishment and risks of impacts. Rounding up is a conservative measure to counteract the uncertainty associated with the risk assessment process and biological situations (ANSTF 1996).

An expert stakeholder panel was selected to represent a wide range of expertise and experience, with eleven panel members recruited from state and federal agencies, industry, and academia, including two members of the Alligator Gar Technical

Committee of the Southern Division of the American Fisheries Society (Table 2-1).

Stakeholders were selected by the project team or the entities that they represented, and participation was confirmed by email. Stakeholders were invited to attend the workshop and complete the qualitative risk assessment.

Panel members received information packets for the qualitative assessment by email, two weeks prior to the workshop held at the UF/IFAS Tropical Aquaculture

Laboratory in Ruskin. The packet materials were comprised of the Alligator Gar biological synopsis, the FISK risk assessments, two referred publications describing and providing examples of the FISK assessment process (Lawson et al. 2013; Hill and

Lawson 2015), a report from the Aquatic Nuisance Species Task Force describing the

Generic Analysis (ANSTF 1996), and a publication providing an example of the use of

Generic Analysis (Hardin and Hill 2012). All panel members were asked to review informational materials prior to the stakeholder workshop to familiarize themselves with

content and procedures, as well as to provide comments or corrections for the biological synopsis and FISK assessments. Some of these materials are included in the results.

The stakeholder workshop and qualitative assessment took place over two days,

April 29 and 30, 2019. Eight stakeholders attended the workshop, with day 1 involving introductions of stakeholders and the project team, an overview of the goals and objectives, and five informal presentations (Table 2-3) to provide additional background information on Alligator Gar, risk assessment, non-native species, and best management practices, followed by a question and answer session. Day 2 included a brief discussion of the agenda and a question and answer session prior to the completion of the qualitative risk assessment.

The qualitative risk assessment was completed in two breakout group sessions composed of varying stakeholder members, with the first session evaluating the probability of introduction and establishment (Appendix A) followed by a group discussion and a second breakout session discussing potential impacts of introduction

(Appendix A). The groups were selected to provide equal representation from all stakeholder backgrounds and allow greater for the opportunity for stakeholders to put forward thoughts, questions, and opinions. Each breakout group was assigned a project team member to facilitate discussions, with a moderator available to answer questions for all groups throughout the process. The group discussion following each breakout group, as well as the final group discussion, was used to determine the ORP for each breakout group as well as the collective stakeholder panel. The project team facilitated the meeting and attempted to answer stakeholder questions throughout the risk assessment related to facts, the process, or direct questions to the panel members. The

project leader (JEH) was the main facilitator and moderator for the workshop. Lastly, a facilitated group discussion on impacts, the overall risk level, and risk mitigation occurred after the completion of the generic risk assessment.

The overall group discussion following both breakout groups and subsequent discussions attempted to result in a consensus for the risk level of Alligator Gar aquaculture in Florida, but consensus was not required. A discussion of risk mitigation was introduced after the Generic Analysis to discuss current best management practices and whether there would need to be further changes in management and protocols to mitigate risk to an acceptable level. Before concluding the stakeholder workshop, panel members were invited to complete an anonymous qualitative evaluation (Appendix B) assessing the stakeholders’ participation, satisfaction, agreement, and requesting further comments of the stakeholder qualitative assessment.

Any further comments or edits from the stakeholder panel for the Alligator Gar biological synopsis and FISK v2 risk screenings were solicited by the project team and requested to be sent within three weeks of the stakeholder workshop. The deadline for comments on the materials, process, outcome, or associated aspects of the risk analysis process was May 22, 2019.

Information from the biological synopsis, FISK risk screen, stakeholder panel, and Generic Analysis was analyzed to identify research gaps and risk factors that may be important for management decisions in Florida, with recommendations made to fill the research gaps. Additional management recommendations based on information generated from this project was also provided.

Table 2-1. Stakeholder panel members’ affiliation and experience. Panel members were not compensated or provided with travel funds by the project team for their participation, though dinner (April 29), breakfast (April 30), and break refreshments (both days) were provided.

Stakeholder Affiliation Title/Experience Brandon Florida Fish and Wildlife Geneticist, Fish and Wildlife Barthel Conservation Commission Research Institute John Galvez U.S. Fish and Wildlife Service Project leader Howard Jelks U.S. Geological Survey Research Fish Biologist, Wetland and Aquatic Research Center Eric Johnson Florida Fish and Wildlife Regional Fisheries Conservation Commission Administrator, Division of Freshwater Fisheries Management Cortney Ohs University of Florida, Program in Associate Professor, Fisheries and Aquatic Sciences Aquaculture, Indian River Research and Education Center David Rawlins Florida Aquaculture Association Commercial Fish Farmer Portia Sapp Florida Department of Director, Division of Aquaculture Agriculture and Consumer Services Andrea Florida Fish and Wildlife Risk Assessment Coordinator, Sizemore Conservation Commission Wildlife Impact Management Section John Skidmore Florida Tropical Fish Farms Commercial Fish Farmer Association Richard Snow Oklahoma Department of Wildlife Biologist, Oklahoma Fishery and Conservation & SDAFS Alligator Research Laboratory Gar Technical Committee Matthew Florida Fish and Wildlife Biologist, Blackwater Research Wegener Conservation Commission & and Development Center SDAFS Alligator Gar Technical Committee

Table 2-2. Project team, affiliations, and title/expertise.

Project Team Affiliation Title/Expertise Allison Durland Donahou University of Florida, Ph.D. Student under Dr. School of Natural Jeffrey Hill; ecology and Resources and the life history of non-native Environment, Tropical aquatic species, risk Aquaculture Laboratory assessment Jeffrey Hill University of Florida, Associate Professor; Program in Fisheries and ecology of non-native Aquatic Sciences, Tropical fishes; risk analysis; Aquaculture Laboratory project principal investigator Lauren Lapham University of Florida, M.S. Student under Dr. Program in Fisheries and Jeffrey Hill, risk Aquatic Sciences, Tropical assessment of Alligator Aquaculture Laboratory Gar aquaculture in Florida Josh Patterson University of Florida; Assistant Professor; Program in Fisheries and restoration aquaculture, Aquatic Sciences, Florida Alligator Gar aquaculture Aquarium at Apollo Beach Quenton Tuckett University of Florida, Research Assistant Program in Fisheries and Scientist; aquatic ecology Aquatic Sciences, Tropical and non-native species, Aquaculture Laboratory risk analysis; project co- principal investigator

Table 2-3. Stakeholder presentations, presenters, and affiliations.

Presentation Title Presenter Affiliation Alligator Gar Matthew Wegener FWC Nonnative Fish in Jeffrey Hill UF/IFAS Tropical Aquaculture Florida Laboratory Aquaculture BMPs Portia Sapp FDACS and BMP evaluation Quenton Tuckett UF/IFAS Tropical Aquaculture Laboratory Risk Assessment: Jeffrey Hill UF/IFAS Tropical Aquaculture FISK and Generic Laboratory Analysis

CHAPTER 3 RESULTS

Biological Synopsis

The study species for the biological synopsis was Alligator Gar Atractosteus spatula, the genus Atractosteus consists of three species, with Alligator Gar being the largest of the gar family and the most widespread of the genus. The historic range of the species consists of 14 states, with six formally listing the species rare or extirpated

(Buckmeier 2008; Jelks et al. 2008).

Alligator Gar are the second largest freshwater fish in North America (Buckmeier

2008) and native to the southeast United States and Mexico; historically found in coastal rivers of the panhandle of Florida, from the Econfina river west along the Gulf

Coastal Plain to Veracruz, Mexico, throughout the Mississippi in Alabama and brackish water of the Gulf Coast and Mobile-Tensaw Delta, north in the Mississippi river basin drainage to southwestern Ohio, Missouri, southern Illinois, and the lowermost

Cumberland and Tennessee Rivers (Lee et al. 1980; Boschung and Mayden 2004;

Froese and Pauly 2018). Literature indicates that Alligator Gar are the most salt tolerant of the gar species, with adults being found to tolerate seawater up to 35 ppt (Suchy

2009; Green et al. 2015). The northernmost native range has temperatures reported as low as 1℃, and high temperatures in the native range have been reported up to 30℃

(Salnikov 2010). The critical thermal maximums of Alligator Gar range from 39.2-44.7℃

(Fernando et al. 2015).

Primary literature indicates that Alligator Gar live over 50 years (Ferrara 2001;

Boschung and Mayden 2004; Roberts and Harrel 2006; Salnikov 2010; Buckmeier et al.

2016) with the minimum age of maturity ranging from 4-11 years. Recent research

indicates younger ages of sexual maturity (4-6 years; Boschung and Mayden 2004;

Salnikov 2010; Ferrara et al. 2015). Volitional spawning of males and females at 4 years of age was observed after undergoing a rapid change in osmotic environment and handling (Patterson et al. 2018). In literature, spawning is associated with flooded, submerged, and weedy areas (Page and Burr 1991; Schultz 2004; Salnikov 2010;

Froese and Pauly 2018). Reproduction in Florida has been confirmed in the Escambia

River, with spawning occurring in flooded backwaters that need a minimum inundation period of 5 days (ideally 60) with water temperatures between 20℃ and 30℃ (Echelle and Riggs 1972). There are research gaps regarding spawning requirements for

Alligator Gar, meaning it is unknown whether these conditions are mandatory for successful spawning and recruitment. If these conditions are necessary, these factors would limit reproduction and successful recruitment in some regions of Florida.

Spawning requirements in aquaculture are well known. Alligator Gar is currently cultured in federal hatcheries in the United States (e.g. the Private John Allen National

Fish Hatchery; Tishomingo National Fish Hatchery) for restoration purposes.

The most likely mechanisms of impact in the risk assessment area would be predation on native species, competition with native species for food, and hybridization with native gar. The introduction of other large, predatory fish has had negative impacts documented in Florida. The predatory effects of the non-native Flathead Catfish

Pylodictis olivaris has reduced the abundance of Redbreast Sunfish Lepomis auratus and two bullhead catfishes Ameiurus spp. the Apalachicola River (Dobbins et al. 2012).

Despite Alligator Gar being a large, predatory, piscivorous fish, reintroduction studies

(Richardson 2015) indicate that there is little evidence of prey depletion or competition.

Diet studies in a re-introduced population in western Kentucky suggests opportunistic feeding behavior and a lack of diversity in abundant prey, resulting in dietary overlaps for four sympatric gar species (Richardson 2015).

Hybridization has been documented in the wild and aquaria, with most concern associated with native Longnose Gar Lepisoteus osseus. There is ongoing research in

Florida to assess the possibility of hybridization with other gar species in the Pensacola

Bay watershed (Wegener 2018).

Factors that consistently influence invasion success across taxa and regions include invasion history, high climate match and propagule pressure (Hayes and Barry

2008; Copp et al. 2010). The literature review revealed minor history of introduction of individuals outside of the native range of Alligator Gar, with no successfully established populations indicated in literature (Fuller 2019). Alligator Gar have a high climate 6 score (0.92) in Florida, a characteristic that is indicative of higher invasion potential and increased risk. The most suitable climate match for Alligator Gar was in the western

Panhandle, where Alligator Gar are native, as well as across north Florida towards the east coast and south along the east coast to St. Lucie County. While these areas have the highest climate match, the climate match illustrated that most of Florida is a suitable climate for Alligator Gar with a similarity score of ≥ 6. Most of Florida has suitable habitat for adult Alligator Gar, but there is uncertainty regarding potential habitat availability for spawning and recruitment success.

Florida has seemingly suitable habitat in the coastal river systems along the northern Gulf of Mexico coast east of the current range of Alligator Gar, including the

Suwannee River in Florida’s Big Bend. Most of these systems periodically flood

(SRWMD 2017) presenting potential spawning and nursery habitat for Alligator Gar.

Rivers draining on the west coast of Florida may be less suitable for Alligator Gar, exceptions may include the Peace River, as most systems have relatively small floodplains and short periods of floodplain inundation that are not ideal nursery or spawning habitat for Alligator Gar. South Florida has extensive wetlands that may provide suitable habitat if Alligator Gar can tolerate low water periods by utilizing canals or solution holes as refuge habitat. Potential detractors for the suitability of the east coast habitats is the few potential spawning/nursery areas, however, it was discussed during the risk assessment process that Alligator Gar have exhibited volitional spawning in earthen ponds following handling, transfer to a new pond, and a change in salinity

(Patterson et al. 2018). Lake Okeechobee or lakes within the St. Johns River basin may present suitable habitat if Alligator Gar can spawn in more lentic systems. The

Longnose Gar is a lotic spawner that spawns in channels rather than backwaters, however, the species successfully spawns and recruits in both systems (Holloway 1954;

Johnson and Noltie 1996; Gandy et al. 2012). An aspect of Alligator Gar biology that may present limitations to movement is the timing of flooding. Literature states that

Alligator Gar spawning is associated with flood events (Page and Burr 1991; Schultz

2004; Salnikov 2010; Froese and Pauly 2018), while the Alligator Gar has an extended spawning period across its native range (January to September; Echelle and Riggs

1972), flood periods in the peninsula may not coincide with spawning habits.

Research gaps identified in the literature review were associated with reproduction, impacts of introduction, population genetics, and hybridization. There is

limited information for Alligator Gar in Florida, with movement and genetic research ongoing (Wegener 2018).

Increased interest in Alligator Gar for sport and conservation purposes

(Buckmeier et al. 2016) was reflected in the literature review, with publications showing a marked increase in the mid 2000’s (Figure 3-15). The decline of Alligator Gar populations throughout most of their native range has resulted in an increased interest in aquaculture of Alligator Gar. Resources for the literature review varied, with 115 references listed in the biological synopsis. The characterization of literature published also reflects the change in perception regarding Alligator Gar. Web of Science

(wcs.webofkowledge.com) lists 84 publications for Alligator Gar, with nearly half (47%) listed as fisheries publications.

Data and information that were found to be lacking during the literature review was noteworthy as the lack of information would likely be interpreted as an element of higher risk, potentially changing the risk assessment of Alligator Gar aquaculture in

Florida. It is important to identify information and data gaps to aid in providing recommendations and identifying future research needs.

Alligator Gar Atractosteus spatula Biological Synopsis

Figure 3-1. Florida Fish and Wildlife Conservation Commission. Alligator Gar. May 30, 2014. Escambia River. Source: Florida Fish and Wildlife Conservation Commission. 2019. Florida Fish and Wildlife Conservation Commission, Tallahassee, Fl.

Classification

Taxonomy, common names, and references

Super Class: Actinopterygii

Class: Holostei

Order: Lepisosteiformes

Family: Lepisosteidae

Genus: Atractosteus

Atractosteus spatula (Lacepède, 1803)

English common names for the species include Alligator Gar, Gemfish, Great

Gar, Garpike, Mississippi Alligator Gar or Gator Gar (Ross 2001; Froese and Pauly

2018).

The Alligator Gar was first described in 1803 as Lepisosteus spatula (Lacepède,

1803); synonyms include Litholepis adamantinus Rafinesque, 1818, Atractosteus adamantinus (Rafinesque, 1818), Lepisosteus ferox Rafinesque, 1820, Lepisosteus

berlandieri Girard, 1858, and Atractosteus lucius Duméril, 1870 (Froese and Pauly

2018). FishBase (Froese and Pauly 2018) also lists Esox cepedianus Shaw, 1804 as an ambiguous synonym of the Alligator Gar. The name was changed to Atractosteus spatula in 1976 by Wiley to recognize two genera of gars (Wiley 1976; Goddard 2009).

The genus Atractosteus derives from the Greek word for spindle, atractus, and osteos, meaning bony. The species name spatula derives from the Latin derivative of the Greek word spathe, which refers to a tool with a broad, flat blade.

The family Lepisosteidae represents two genera of gar, containing 7 species total: shortnose or broadhead gars Atractosteus (Rafinesque 1820) and longnose gars

Lepisosteus (Lacepède 1803; Salnikov 2010). Lepisosteidae are survivors of a group that first occurred in the upper Permian period and flourished in the Triassic and

Jurassic periods. The family is known for long, sharply toothed jaws; the placement of dorsal and anal fins far back on the body; and diamond shaped ganoid scales (Page and Burr 1991). Gars are considered primitive fish due to the characteristic ganoid scales, abbreviated heterocercal tail, and highly vascularized physostomous swim bladder that can be used as a lung to gulp air at the surface (Page and Burr 1991).

Atractosteus have two rows of conical teeth on the maxilla. One row of teeth is located on the preorbital bone and is part of the maxilla while the second row is located inside the first row and located on the palatal bone (Page and Burr 1991; Schultz 2004).

The genus Lepisosteus has only one row of teeth that are located on the preorbital bone

(Page and Burr 1991; Boschung and Mayden 2004). There are three species of shortnose gars: A. spatula, Cuban Gar A. tristoechus, and Tropical Gar A. tropicus.

Alligator Gar is the largest of the seven species and the most widespread Atractosteus.

Alligator Gar is often mistaken with the more commonly encountered gar species such as the Shortnose Lepisosteus platostomus or Spotted Gar Lepisosteus oculatus

(USFWS 2016) or the Florida Gar Lepisosteus platyrhincus in much of Florida. Of the 7 gar species, Alligator Gar is considered uncommon, with increased abundance in swamps and bayous in the southern parts of the United States (Page and Burr 1991).

Physical description and identifying characteristics

Alligator Gar grows considerably larger than other gars found in North America,

Central America, and Cuba (Ross 2001; Boschung and Mayden 2004; Fuller 2019).

Alligator Gar has a distinctive broad snout which differentiates them from other gar species in the United States. This species has a large, cylindrical body covered in heavy, interlocking diamond shaped ganoid scales (Ross 2001; Schultz 2004). Alligator

Gar also has triangular and laterally compressed gill rakers (Ross 2001; Schultz 2004;

Froese and Pauly 2018). The broad short snout distinguishes the Alligator Gar from other gar species in the United States. The species, like others of its genus, has two rows of teeth on its upper jaw (Page and Burr 1991; Schultz 2004). Alligator Gar, similar to other gar species, have a rounded heterocercal caudal fin, a single dorsal fin that is placed far on the back and above the anal fin, and evenly spaced pectoral, ventral, and anal fins on the lower half of the body (Schultz 2004). There are 34-38 transverse scale rows between the anal fin and middorsal position (Ross 2001). Alligator Gar has a dark olive brown color, occasionally black, on the dorsal and ventral planes that becomes a yellow to white color towards the ventral side (Page and Burr 1991; Ross 2001;

Boschung and Mayden 2004; Schultz 2004). The body is occasionally spotted or mottled with large black spots (Page and Burr 1991; Schultz 2004). The dorsal, anal,

and caudal fins have a dark brown background with dark spots (Ross 2001). The

Alligator Gar has 7-10 dorsal rays, 7-10 anal rays, and 11-15 pectoral rays (Ross 2001).

The species has 58-62 lateral scales, 48-54 predorsal scales, and 59-66 gill rakers

(Page and Burr 1991). The head, from tip of the snout to occipent is 3.1-4.6 inches total length; from snout tip to the anterior rim of orbit is 4.7-6.4 inches total length (Boschung and Mayden 2004).

Figure 3-2. U.S. Fish and Wildlife Service. Juvenile Alligator Gar of normal and leucistic coloration. March 3, 2015. Source: United States Fish and Wildlife Service. 2019. United States Fish and Wildlife Service, Washington, D.C. Reprinted with permission from the U.S. Fish and Wildlife Service Online, https://www.fws.gov/ (January 4, 2019).

Figure 3-3. Florida Fish and Wildlife Conservation Commission. Juvenile Alligator Gar. 2018. Source: Wegener, M. 2018. Annual Project Report: Florida Fish and Wildlife Research Institute - Freshwater Fisheries Research. Florida Fish and Wildlife Conservation Commission, Tallahassee, Fl.

Figure 3-4. U.S. Fish and Wildlife Service. Adult Alligator Gar. 2019. Source: United States Fish and Wildlife Service.2019. United States Fish and Wildlife Service, Washington, D.C. Reprinted with permission from the U.S. Fish and Wildlife Service Online, https://www.fws.gov/warmsprings/ (January 5,2019).

Adults, on average, are 1.2-1.8 meters total length, but the species can grow up to 3.1 meters total length (Suttkus 1963; Boschung and Mayden 2004; Salnikov 2010;

Froese and Pauly 2018). Adults can weigh 45–73 kg; however, they have been found to

159 kg (Boschung and Mayden 2004; Salnikov 2010; FishBase 2018). The largest

Alligator Gar recorded in Florida was 60 kg, collected by researchers in 2011 in the

Yellow River (FWC 2019a).

The world record Alligator Gar was estimated to be 94 years old; it measured 2.6 meters and 148 kg (Figure 3-5; Gemming 2017). It was caught in 2011 in Lake Chotard,

Mississippi (Love 2011).

Figure 3-5. Travis Fillmen. Adult world record Alligator Gar, 2.6 m, 148 kg. July 2, 2015. Vicksburg, Central Florida Aquarium Society. Source: Fillmen, T. 2015. Massive 327 Pound Alligator Gar Measures Over 8 Feet Long. Central Florida Aquarium Society. Reprinted with permission from the Central Florida Aquarium Society, https://cflas.org/2015/07/02/massive-327-pound-alligator-gar-measures-over-8-feet- long/ (January 4, 2019).

Platinum or Snow Alligator Gars (Figure 3-6) are a color variant of the Alligator

Gar; the gar are completely white as a result of a pigmentation disorder, leucism, which is a genetic mutation that inhibits pigment deposition resulting in white, pale, or patchy coloration of the scales (https://www.merriam-webster.com/dictionary/leucism). Platinum

Alligator Gar are popular and highly valued in the ornamental fish trade, especially overseas. The low occurrence of Platinum Alligator Gar makes them highly valued and also expensive; recent prices for 6-inch Platinum Alligator Gar are ~$1,250 online

(https://exoticfishshop.net/product/platinum-aligator-gar/) and reported $5-20,000 for a

12” leucistic Alligator Gar (personal communication Craig Watson, University of Florida).

The value of normal coloration Alligator Gar is still high, with an estimated $15 wholesale price for a 4” juvenile.

Figure 3-6. Photo courtesy of author. Platinum (or snow) Alligator Gar. January 4, 2019. Source: Lapham, L. 2019. Platinum (or snow) Alligator Gar. University of Florida, Institute of Food and Agricultural Sciences, Tropical Aquaculture Laboratory. Ruskin, Fl.

Genetics

Initial genetic studies found little mixing of estuarine and river (interior) Alligator

Gar populations (Bohn et al. 2013). More recently, Bohn et al. (2015) sampled Alligator

Gar from 16 sites across their native range and genotyped them for 8 microsatellite loci.

This study found 5 genetically distinct regions: the Rio Grande River and Choke Canyon

Reservoir, the Brazos River, eastern Texas including the Trinity River, the Mississippi

River drainage, and the northern Gulf Coast including coastal sites from southern

Louisiana to the Florida panhandle.

Hybridization between Alligator Gar and Longnose Gar Lepisosteus osseus is documented in captivity (Herrington et al. 2001). Hybridization between wild Alligator

Gar and Longnose Gar has been documented (Bohn et al. 2017). Hybridization has never been documented in Florida, despite the sympatric occurrence of native Alligator

Gar, Longnose Gar, and Spotted Gar in the panhandle. Studies are currently underway to examine whether hybridization is occurring in the Escambia, Blackwater, and Yellow

Rivers (Wegener 2018).

A combination of otoliths and mitochondrial DNA has been used to better understand population structure of Alligator Gar in the Guadalupe River (Texas) where freshwater systems transition to saltwater bays of the Gulf of Mexico (Daugherty et al.

2017b). Three distinct life histories were revealed: river resident, transient, and bay resident. River resident species were considered exclusive to freshwater and found most commonly in the upper reaches of the river. Transient fish used both river and bay habitats and were most commonly found in the lower reaches of the river. Bay fish were exclusive to brackish water (13 ppt) and were the least common (Daugherty et al.

2017b). Mitochondrial DNA indicated that haplotype diversity was lowest in the upper river, indicating limited gene flow compared to the lower river and bay (Daugherty et al.

2017b). The differences in Alligator Gar movement and genetics along the interface of the river bay continuum indicated a river resident stock that dominates the upper river and a transient stock that dominated the lower river and bay (Daugherty et al. 2017b).

There is genetic differentiation between coastal and inland Alligator Gar populations. Juvenile Alligator Gar were collected from an inland population (St.

Catherine Creek National Wildlife Refuge, Mississippi) and a coastal population

(Rockefeller State Wildlife Refuge, Louisiana) to compare salinity regulatory ability

(Allen et al. 2015). Allen et al. (2015) acclimated both populations for two weeks to 0 or

20 ppt and 10 or 30 °C. After the acclimation period survival, gill Na+, K+-ATPase activity, plasma osmolality, and plasma and gut fluid ion concentrations were sampled and found to be similar between populations despite genetic differentiation. It was noted by Allen et al. (2015) that neither population regulated ions well at 10 °C and 20 ppt.

Distribution

Native range

Alligator Gar is native to North America from the Econfina River, Florida, west along the Gulf Coastal Plain to Veracruz, Mexico, including the Mississippi Sound in

Alabama and brackish water of the Gulf Coast and Mobile-Tensaw Delta; north in the

Mississippi river basin drainage to southwestern Ohio, Missouri, southern Illinois, and the lowermost Cumberland and Tennessee Rivers (Lee et al. 1980; Boschung and

Mayden 2004; Froese and Pauly 2018). The species ranges from 44-20° N and 101-

80°W (Salnikov 2010).

In the Florida panhandle, Alligator Gar are found in coastal rivers flowing into the northern Gulf of Mexico (Boschung and Mayden 2004). Recent studies indicate that

Alligator Gar only occur in Gulf Coast rivers west of the Apalachicola River; historic records indicate populations of Alligator Gar in Choctawhatchee River, Escambia River, and Econfina Creek (Hoehn 1998). Wegener (2018) notes personal observations of

Alligator Gar in the Yellow and Blackwater Rivers. There are reports of Alligator Gar in the Gulf of Mexico; however, those sightings are rare(https://www.nationalparkstraveler.org/2017/07/alligator-gar-spotted-along-floridas- gulf-islands-national-seashore).

Figure 3-7. GBIF. Map of North American range occurrences of Alligator Gar, including the native range. Occurrences in Peninsular Florida are misidentifications and not representative of established populations of Alligator Gar. December 20, 2019. Source: Global Biodiversity Information Facility (GBIF). 2019. http://www.gbif.org.

Figure 3-8. United States Geological Survey. Known distribution of established Alligator Gar populations in the United States. September 1, 2018. Source: United States Geological Survey. 2019. Alligator Gar Atractosteus spatula. United States Geological Survey. https://nas.er.usgs.gov/queries/factsheet.aspx?SpeciesID=755

Figure 3-9. Florida Fish and Wildlife Conservation Commission. Map of sustaining, historic, remnant, and stocked populations of Alligator Gar throughout their native range. 2019. Source: Florida Fish and Wildlife Conservation Commission. 2019. Alligator Gar presentation, Alligator Gar stakeholder meeting. Florida Fish and Wildlife Conservation Commission, Tallahassee, FL.

Expansion/contraction

Alligator Gar are imperiled or rare throughout much of their native range, particularly around the perimeter of the native range (Buckmeier 2008). Abundance in some regions has declined due to unregulated fishing, eradication efforts, and habitat loss beginning in the 20th century (Scarnecchia 1992; Buckmeier 2008; Buckmeier et al.

2017). Habitat loss and hydrologic changes (e.g., dams) have reduced or restricted access to spawning floodplains (Mettee et al. 1996).

Alligator Gar is extirpated from much of its historic northern range in the

Mississippi River basin in Missouri, Illinois, Ohio, and Kentucky (Buckmeier 2008). For example, Alligator Gar is designated extirpated in the Wabash River drainage in the midwestern United States. The species was associated with the wetlands that surround the Wabash River, but have not been collected there since the 19th century, likely due to the draining of the wetlands beginning in the late 19th century (Simon 2006).

Individuals of the species have been reported outside their native range, but not established, in South Carolina and California (Fuller 2019).

Relative abundance

There is a closed harvest on Alligator Gar in Florida because of limited data for

Florida populations; however, research on abundance and distribution is ongoing to determine the appropriate status and management of Alligator Gar in Florida. Wegener

(2018) reports that less than 10 Alligator Gar have been captured in Pensacola Bay rivers other than the Escambia but that 212 Alligator Gar were captured in the Escambia

River in 2015 (Wegener 2018). Research indicates that the estimated population in

Pensacola Bay drainages consists of at least 212 individuals with a calculated 95% C.I. up to 328 individuals (Wegener 2018). While conducting a telemetry study in 2016 in

Pensacola Bay, Florida, no Alligator Gar was collected in the Yellow River, however, personal observations recorded in Wegener (2018) note observations in the Yellow and

Blackwater Rivers. This might indicate a small, non-existent, or non-permanent population in the Yellow River (Wegener 2018). Hoehn (1998) categorized Alligator Gar

in Florida as very rare and local throughout its native range (6-20 occurrences or less than 10,000 individuals) or found locally in a restricted range. In this case, threatened is defined (by FWS) as a species that may be relatively abundant but is subjected to serious adverse pressures throughout their range (Hoehn 1998).

Of the 14 states where Alligator Gar were native historically, 6 now consider the species to be rare or extirpated (Buckmeier 2008; Jelks et al. 2008). Populations are facing declines due to habitat loss, overfishing, and impacts from historic removal efforts

(Scarnecchia 1992; Ferrara 2001; Buckmeier 2008; USFWS 2017). Alligator Gar has been extirpated from Ohio and Illinois and is considered imperiled or critically imperiled in Alabama, Arkansas, Indiana, Oklahoma, Kentucky, Mississippi, and Tennessee

(Brinkman 2003). Alligator Gar is considered vulnerable in Florida. It is estimated that

Alligator Gar populations have experienced a 30-70% decline from historic levels throughout their native range (www.natureserve.org). However, populations are considered robust in Texas and Louisiana (Brinkman 2003).

Studies suggest some populations are far below historic levels and continue to decline, to the point of requiring reintroduction through stocking (USFWS 2016). The

American Fisheries Society identifies Alligator Gar as vulnerable (Hassan-Williams and

Bonner 2013) and numerous states are in the process of changing management and conservation regulations as well as considering stocking (Buckmeier 2008; USFWS

2016).

Alligator Gar populations in the Vincente Guerrero Reservoir (Mexico) do not appear vulnerable to overfishing, likely because fishing is confined to 7 months of the

year and harvest is biased towards males (Garcia de Leon et al. 2001). Populations in

Mexico support an active gill net fishery (Garcia de Leon et al. 2001).

Threats

Harvest has been a threat to Alligator Gar over long time periods. Native

Americans once used Alligator Gar scales as arrowheads, ornaments, tools, and consumed Alligator Gar. Early settlers used Alligator Gar hides to cover wooden plowshares in addition to consuming this fish (Scarnecchia 1992; Schultz 2004).

Alligator Gar and other “rough fish” were the targets of eradication efforts to improve fishing for more desirable species (Scarnecchia 1992; Schultz 2004). Recreational and commercial fishing still occur in some regions, though under more directed fisheries management than in the past (Binion et al. 2015). Human impacts and predation by alligators Alligator mississippiensis are listed as threats to Alligator Gar (Ross 2001).

Habitat alteration and loss have been major pressures on Alligator Gar populations (Etnier and Starnes 1993). Dams have been constructed that limit movement of this species (Etnier and Starnes 1993; Mettee et al. 1996). Stream channelization, destruction of bottomland forests, separating floodplains from river channels by constructing berms, and other alterations have negatively affected Alligator

Gar populations in some regions (Etnier and Starnes 1993).

Alligator Gar are vulnerable to overfishing despite their long lifespan and high fecundity because of the low population numbers and late sexual maturity to a minimum population doubling time of over 14 years (Froese and Pauly 2018).

If there are no length restrictions, Smith et al. (2017) estimate that harvest rates of 6.5% a year would result in overharvesting of Alligator Gar. Males are thought to be

more vulnerable to harvest because they remain in the spawning area for extended periods (Suttkus 1963; Garcia de Leon et al. 2001).

The small, isolated population of Florida’s Alligator Gar is a threat to the population as the populations could easily be reduced or extirpated as a result of human activity. While the harvest closure in Florida protects the species from fishing pressures, the population is threatened by development. If there is a reduction or obstruction to floodplain spawning grounds, the species cannot successfully reproduce.

Habitat and Movement

Physical (substrate, temperature, flow, depth)

Alligator Gar are demersal and inhabit large bays, rivers, swamps, bayous, lakes and coastal marine waters (Lee 1980; Froese and Pauly 2018). Alligator Gar exhibit preferences for weedy and shallow backwater sites with slow moving to moderate currents (Kluender 2016) or oxbows, reservoirs, and brackish estuaries along the Gulf of Mexico (Page and Burr 1991; Schultz 2004; Salnikov 2010; Allen et al. 2014;

Kluender 2016; Froese and Pauly 2018). Literature suggests that Alligator Gar populations (e.g. brackish populations) in the eastern Gulf of Mexico rarely travel very far upstream, primarily remaining in coastal streams along the northeast Gulf of Mexico

(Boschung and Mayden 2004; Buckmeier et al. 2013). Populations found in the

Mississippi are known to travel far upstream (Mettee et al. 1996; Boschung and Mayden

2004).

In Alabama they are commonly found over sand, gravel, silt, or mud (Mettee et al. 1996). The maximum reported depth for Alligator Gar is 60 m (Gulf Base 2016).

Schultz (2004) notes that the species can survive hot, stagnant waters and they are

rarely found in brackish and marine waters (Page and Burr 1991). Ross (2001) reports that Alligator Gar have the highest tolerance for saltwater of all gar species, they have been observed in the Gulf of Mexico waters from Louisiana through Destin, Florida.

Alligator Gar is found in the Pensacola Bay System of Florida, which is a river dominated system where freshwater flows influence salinity. The system encompasses the Escambia River and Blackwater River where temperature ranges from 8℃ to 33.7℃, averaging 22.2℃ (USEPA 2004). The pH for the system ranges from 4.1-9.1, with an average of 7.8 (USEPA 2004). Hobbyist literature (www.numa.sk) notes that the temperature can range from 15-32℃. The Warm Springs Hatchery uses filtered pond and spring water to culture Alligator Gar (USFWS 2014). The water temperatures are gradually increased through the production season by blending spring and pond water to increase temperatures from 21℃ in May to near 28℃ in July (USFWS 2014).

Alligator Gar has a wide geographic range that encompasses 44-20° N and 101-80° W, in the northernmost native range has temperatures have been reported as low as 1℃ and recorded highs of the native range have been 30℃ (Salnikov 2010). Fernando et al.

(2015) proposed that thermal tolerance may vary among Alligator Gar populations due to local adaptations. Juvenile Alligator Gar from three populations in the Mississippi

River were studied at temperatures of 25-35℃ for thermal tolerance consistency and critical thermal maximum tolerance among populations (Fernando et al. 2015). Results demonstrated consistency of thermal tolerance among populations, with individual critical thermal maximums ranging from 39.2-44.7℃ (Fernando et al. 2015).

General (terrestrial, estuarine, marine, freshwater)

While Alligator Gar is a freshwater species more commonly found in fresh than brackish or saltwater (Froese and Pauly 2018), Suttkus (1963) notes that the species

(under L. spatula) is considered a common inhabitant of brackish water in Louisiana.

Suttkus (1963) discusses that multiple specimens have been found from in the Gulf of

Mexico, on the Gulf side of Breton Island and Grand Isle, Louisiana, and at Destin,

Florida. In Texas, Alligator Gar is routinely captured in estuarine habitats with salinities over 20 ppt (Buckmeier 2008).

Alligator Gar is the most saline tolerant of all gar species; however, they only spawn in freshwater (Mettee et al. 1996; Boschung and Mayden 2004). It has been observed that larval Alligator Gar cannot tolerate salinities higher than 8 ppt; however, adults can thrive in seawater up to 35 ppt (Suchy 2009; Green et al. 2015). Juveniles under one year can tolerate salinity of 24 ppt for 30 days but show reduced growth attributed to decreased appetite (Schwarz and Allen 2013).

Alligator Gar larvae over 40 DPH (Days Post Hatch) can survive salinities up to

18 ppt (Green et al. 2015). Based on LC50 dose response values, salinity tolerance of larval Alligator Gar increased in stages, with the first increase occurring at 10 DPH and another increase at 25-30 days post hatch (Green et al. 2015). Observed biomarkers for ion analysis and NKA activity and noted changes as acute salinity tolerance increased again from 15 to 40 DPH (Green et al. 2015). Based on salinity tolerance development,

Green et al. (2015) proposed a developmental response to salinity that is conserved among coastal and inland populations.

Chemical (pH, salinity, dissolved oxygen)

Alligator Gar are a freshwater fish with adults exhibiting a high tolerance to salinity levels. Alligator Gar larvae cannot tolerate salinity over 8 ppt; however, adults can tolerate salinity levels over 35 ppt (Buckmeier et al. 2008; Suchy 2009; Green et al.

2015; Daugherty et al. 2017a). Gars can also tolerate a range in pH and water hardness levels and their highly vascular air bladder enables them to thrive in a low dissolved oxygen environment by taking in air at the surface (Schultz 2004). Hobbyist literature

(www.numa.sk) notes the preferred pH range is 6-8, hardness 90-450 ppm, and that filtration is a big concern in aquaria due to the meaty, high protein diet, and waste levels.

Warm Springs Hatchery uses filtered pond and spring water to culture Alligator

Gar (USFWS 2014). The constant temperature of the water was buffered to an alkalinity of at least 51 and a hardness of 83 ppm. Fluidized high calcium content limestone was utilized in the buffering system to keep pH between 6.5 and 7.

Biological (plant cover, species associations)

Alligator Gar spawns annually if seasonal flooding conditions are met (Schultz

2004). Spawning is associated with floodplain habitats or flooded and submerged, shallow, and weedy areas (Page and Burr 1991; Schultz 2004; Salnikov 2010; Froese and Pauly 2018). The optimal substrate for spawning is herbaceous wetlands; however,

woody debris and scrub bushes are also suitable (Buckmeier et al. 2017; Most and

Hudson 2018).

Habitat Movement and Use

During cold months (December-March), Florida Alligator Gar show strong site fidelity to off-channel habitats and travel less frequently than in warm months (April-

November) (Wegener et al. 2017). As temperatures become warmer, Alligator Gar relocate into the main channel and aggregations disperse (Brinkman 2003; Kluender

2016; Wegener et al. 2017). Previous telemetry projects in Pensacola Bay (2016) showed seasonal variation in habitat use (Wegener 2018). Bay habitats were used more frequently than river habitats in colder months (December-April) and use of river habitats increased from May to October (Wegener 2018). It is proposed that the habitat shifts are due to thermal refuge or changes in food availability (Wegener 2018). There are indications that Alligator Gar in the Escambia River use off-channel habitats and move less in the winter than warmer seasons (May-October), while they use both main and off channel habitats in the warm season (Wegener et al. 2017).

Alligator Gar are capable of long-distance migration but have been observed to have a small home range. Buckmeier et al. (2013) suggest that estuarine Alligator Gar do not move far upriver. Throughout the year, the linear home range for Alligator Gar in

Pensacola Bay averaged 41.32 km and ranged from 0.89-101.58 km (Wegener et al.

2017). Wegener also notes that the linear home ranges and rate of travel for Alligator

Gar differed between seasons.

Telemetry studies in the Alligator Gar’s native range has provided insights into movement and habitat use. These studies provide insights into how habitat loss and

alterations can impact Alligator Gar. In Alabama, the greatest recorded distance for

Alligator Gar movement is 10.2 km, while the average daily travel is 1.56 km (Boschung and Mayden 2004). In Texas, tagged individuals were observed to have a linear home range of less than 60 km; however, several individuals have a home range over 100 km

(Buckmeier et al. 2013). Sakaris et al. (2003) and Brinkman (2003) discuss the linear home range of Alligator Gar to vary from 6.57-16.7 km and the mean areal home range was 1170 ha; these data indicate that adult Alligator Gar exhibit large home ranges and are highly mobile. Alligator Gar in Florida exhibit similar large home ranges and high mobility in warmer weather (Wegener et al. 2017).

Irwin et al. (2001) and Sakaris et al. (2003) suggest that larger Alligator Gar move more than smaller individuals but found no seasonal effects on movement rates in the Mobile-Tensaw Delta (Alabama). High catch rates (Irwin et al. 2001) and multiple recaptures (Sakaris et al 2003) for small Alligator Gar suggests site fidelity is more likely for juvenile Alligator Gar. In their native range, dams have limited access and movement to spawning floodplains (Mettee et al. 1996) which has altered habitat use and movement as well as spawning patterns and success.

In the winter, Alligator Gar are found in deeper waters, as evidenced by trawl nets pulling up Alligator Gar from deep holes and estuaries in Louisiana (Suttkus 1963).

In the summer months, Alligator Gar frequent the surface and are known to exhibit a rolling behavior at the surface, especially in the late summer months when temperatures rise, and dissolved oxygen levels drop (Mettee et al. 1996).

Seasonal movement patterns may be a result of resource partitioning among individual Alligator Gar and are similar to other piscivorous ambush predators

(Buckmeier et al. 2013; Solomon et al. 2013). In site fidelity and movement experiments, Alligator Gar exhibited a range of high site fidelity, long distance movement, and a combination of both characteristics (Allen et al. 2014). Thirteen

Alligator Gar exhibited site fidelity throughout a study in the St. Catherine Creek

(floodplain connected to the lower Mississippi River) whereas five Alligator Gar showed highly variable movement patterns (Solomon et al. 2013). Alligator Gar that exhibited site fidelity occupied small areas ranging from 4.8-12.9 ha while the variable group exhibited an average range of 11.8 ha (Solomon et al. 2013).

Introduced range

No known populations of Alligator Gar exist outside of the historic native range despite the occurrence of individuals collected in other U.S. states and in Asia.

Florida has a single record of Alligator Gar outside its native range in Pellicer Creek, near to the coast in Flagler County, Florida from January 1970 (Fuller 2019). There are no known established non-native populations of Alligator Gar in Florida.

The U.S. Geological Survey Alligator Gar species profile state list of nonindigenous occurrences reports one Alligator Gar removed from Lake Wateree in

Fairfield, South Carolina in 2010. The status of Alligator Gar in the lake and nearby

Catawba River is reported as unknown; however, this is the only report of occurrences in South Carolina noted by USGS (Fuller 2019).

The California Department of Fish and Game (now known as the Department of

Fish and Wildlife) recorded an individual Alligator Gar in the San Joaquin Delta,

California in September 1991 (Raquel 1992). The individual collected was 145.5 cm in total length, 59 cm girth, and weighed 18.6 kg. The record states that the most likely

method of introduction was aquarium release and it has been recorded as failed to establish in the area (Raquel 1992). The temperature and salinity at the point of capture was 25℃ and 4.5 ppt, respectively. The most recent recorded observation of Alligator

Gar in California was in 2013; an individual Alligator Gar was collected from Lincoln

Park Lake in Los Angeles (Fuller 2019). The status of this introduction is considered unknown. The introduction vector for this individual is thought to be aquarium release

(Fuller 2019). Similar to Florida, no verified non-native populations are known to exist in

California.

There are two reports of non-indigenous occurrences of Alligator Gar in Texas, in

2015 and 2016, both stocked for sport (Fuller 2019). Alligator Gar was introduced into

Lake Fairfield, Freestone Texas, in 2015 by the Texas Parks and Wildlife Department.

USGS (Fuller 2019) and Texas Parks and Wildlife Department (2018) report that 146 juvenile Alligator Gar were stocked for sport in an HUC of the Lower Trinity River, Lake

Fairfield, an area just outside of the historic native range. The status of the population in

Lake Fairfield is considered unknown (Fuller 2019). In 2016, three individuals were collected with gill nets from Gonzales Reservoir, in Gonzales County, Texas over a 10- night sampling effort (Binion 2016). Binion did not list the Alligator Gar in the stocking history of the Gonzales Reservoir; however, Texas Parks and Wildlife Department and

USGS (Fuller 2019) note that the species is established in the area.

Alligator Gar is a valuable ornamental and non-native sport fish in Southeast

Asia. In 2009 an article titled “Monster exotic fish found in Hong Kong ponds”

(https://news.abs-cbn.com) reported that at least 16 Alligator Gar were removed from retention ponds in a Hong Kong park. One of the individuals removed from the ponds

was one meter long. In Malaysia, Alligator Gar is one of the 24 introduced freshwater species, most introduced for aquaculture, with a few from aquaria or sport (Chong et el.

2010). Chong found reports of the species being released by pet owners in Malaysia concerning; however, they note that “there had been no serious attempt to list the

Alligator Gar as an introduced species nor to identify threats they posed” and there has been no data collected concerning reports of introduction. FishBase (Froese and Pauly

2018) reports 4 records of occurrence in Thailand. The individuals collected ranged from 85-116 cm; however, occurrence records are undated (Database of IGFA angling records until 2009). The occurrences in Thailand are likely the result of stocked ponds for sport fishing. USGS (Fuller 2019) reported a collection of a single Alligator Gar in

Meulaboh, Indonesia in 2011.

An individual Alligator Gar was caught in Marivan Lake, Iran in 2015 (Fuller

2019). On November 2008, an Alligator Gar was caught by anglers in the southern

Caspian Sea near the coast of Turkmenistan (Salnikov 2010). Conditions in the Caspian

Sea and nearby water bodies are similar to the species environmental preferences exhibited in the native range (Salnikov 2010), but the likelihood of reproduction may be low because no other individuals were captured. Alligator Gar were first reported in Iraq in September 2016; a single specimen was collected in the southern part of the Shatt al-

Arab River, at Om-al-Rasas Island during an ichthyologic survey using gillnets (Mutlak and Faisal 2017). The individual was determined to be an immature male, 900 mm in total length. Mutlak and Faisal (2017) suspect that the aquarium trade is responsible for the introduction of the individual. There are no further records of Alligator Gar in either region.

In 2017, Kawase et al. (2017) published a report of the current state of non- native fishes in the Yodo River, the report involved a field study where the Alligator Gar was reported for the first time in the Yodo River Basin, Japan.

Biology

Reproduction

Alligator Gar are oviparous and usually spawn from April to June, correlating with seasonal flooding (Suttkus 1963; Allen et al. 2014). Spawning only occurs in freshwater environments (Boschung and Mayden 2004; Kluender 2016). The species exhibits external fertilization and no parental care (Mettee et al. 1996; Boschung and Mayden

2004). Ideal water temperature for spawning was reported to be 18-23℃ (Most and

Hudson 2018); however, Alligator Gar were observed to spawn at temperatures of 23-

26℃ in the lower Mississippi drainage (Allen et al. 2014). The minimum duration of inundation for spawning and hatching is 5 days (Buckmeier et al. 2017), while the ideal duration of inundation is 60 days (Most and Hudson 2018) with a water temperature between 20-30℃ (Echelle and Riggs 1972).

It is thought that spawning occurs in flooded backwater areas, but the empirical evidence for the necessity of flooded backwaters is lacking (Buckmeier 2008). Lateral spawning migrations were observed in floodplain areas associated with increased river stages and higher temperature (Buckmeier 2008). Spawning has been linked to seasonal flooding, which can lead to infrequent successful recruitment (Buckmeier

2008). Female Alligator Gar lay relatively large (2.0 ± 0.7 mm; Clay et al. 2009) adhesive dark green eggs at a depth of 0.3-1.3 m that adhere to vegetation or substrate until they hatch (Shultz 2004; Buckmeier et al. 2017; Most and Hudson 2018). The

optimal substrate for spawning is herbaceous wetlands; however, woody debris and scrub bushes are also suitable (Buckmeier et al. 2017; Most and Hudson 2018).

Spawning behavior is like other lepisosteids, where 1-4 males pursue a single female into shallow water and fertilize the eggs with milt (Mettee et al. 1996; Clay et al.

2009). While spawning, Alligator Gar thrash at the surface with their tails while releasing sperm and eggs. Once fertilized, eggs settle to the bottom and stick to substrate, including aquatic vegetation, tree limbs, and other debris (Mettee et al. 1996). When spawning is complete, Alligator Gar return to deeper water and hatching occurs after

48-72 hours of incubation (Mettee et al. 1996; Mendoza et al 2002a; Buckmeier et al.

2017).

Time of year

Alligator Gar spawns are reported in spring (Fuller 2019) and early summer

(April-June in the United States) in shallow bays and sloughs (Schultz 2004), which coincides with seasonal flooding of swamps (Simon and Wallus 1990; Boschung and

Mayden 2004; Buckmeier 2008). Cook (1959) observed apparent spawning in late May and notes that during spawning, gars strike the surface of the water and create commotion (Ross 2001).

It is reported that Alligator Gar spawn in May in Oklahoma (Ross 2001) as well as January to September in Oklahoma and Texas (Echelle and Riggs 1972). In

Alabama, Alligator Gar were observed by Mette et al. (1996) to spawn from late March to early June. In northeast Mexico, Alligator Gar have been observed to spawn from

July to August (Garcia de Leon et al. 2001).

Minimum age

The minimum age of sexual maturity for female Alligator Gar is thought to be 11 years of age while the males are younger, reported sexually mature at 6 years of age

(Boschung and Mayden 2004; Salnikov 2010).

In Louisiana, the sexual maturity of coastal Alligator Gar populations is earlier than commonly reported, with females spawning at 4-6 years, and males at 3 years

(Ferrara et al. 2015).

Volitional spawning of males and females at 4 years of age was observed after undergoing a rapid change in osmotic environment and handling (Patterson et al. 2018).

These fish were originally from Louisiana stock but were kept under aquaculture conditions.

Frequency

Frequency of spawning is thought to coincide with seasonal flooding (Suttkus

1963). Seasonal flooding generally corresponds with April to June in the southeastern

United States (Suttkus 1963; Allen et al. 2014). Literature suggests that Alligator Gar are periodic strategists, spawning when requirements for freshwater flooding, inundation period, and temperature are met (Boschung and Mayden 2004; Kluender 2016).

Fecundity

The fecundity of Alligator Gar correlates with size; absolute fecundity is reported from 130,000-157,000 eggs per female and 4.1 eggs/g body weight; however, fecundity is highly variable (Boschung and Mayden 2004; Buckmeier 2008, Salnikov 2010).

Early life history

Alligator gar hatch after 48-72 hours of incubation (Mendoza et al. 2002a;

Buckmeier et al. 2017). After hatching, larvae average 7 mm TL and use a terminal

adhesive disk on the snout to adhere to substrate (Clay et al. 2009). Newly hatched larvae have a visible yolk sac and adhere to vegetation for five days (or 13.5mm TL) while feeding endogenously on yolk sac contents (Mendoza et al. 2002a; Mendoza et al. 2002b; Clay et al. 2009). Yolk absorption takes 5-10 days, after which gar larvae disperse and do not exhibit a pronounced tendency to school (Simon and Wallus 1990).

While capable of swimming, larvae are not strong swimmers and if larvae are detached from substrate they will sink unless actively swimming (Mettee et al. 1996; Ross 2001).

Simon and Wallus (1990) observed that post yolk sac larvae are 14.9-57.3 mm TL and that fin rays are present in the median and pectoral fins by 14.9 mm TL.

The color pattern of 24 mm Alligator Gar was described by Simon and Wallus

(1990) as jet black dorsum with vivid white areas and a white mid dorsal stripe form the tip of the snout to the dorsal fin (Boschung and Mayden 2004; Aguilera et al. 2011).

Juveniles are solitary and float at the surface like sticks, after the yolk is absorbed the gar can rest motionlessly in a horizontal position at any depth (Simon and Wallus 1990;

Schultz 2004). Very young Alligator Gar have a prolonged notochord that the caudal fin is attached to, the notochord extends into a fleshy posterior filament (Boschung and

Mayden 2004).

Figure 3-10. Kentucky Department of Fish and Wildlife. Coloration of juvenile Alligator Gar. July 14, 2009. Source: Kentucky Department of Fish and Wildlife. 2019. Alligator Gar. Kentucky Department of Fish and Wildlife. https://fw.ky.gov/Fish/Pages/Alligator- Gar.aspx

At five to ten DPH larvae lose their suctorial disk (14.9 mm TL) and begin free swimming and feeding on zooplankton and invertebrates (Simon and Wallus 1989;

Mendoza et al 2002a). The transitional stage when larvae obtain nourishment from the yolk reserves and active predation is known as the lecitho-exotrophic feeding stage

(Mendoza et al. 2002b). Exogenous feeding begins between 12.5 and 22.5 mm TL

(Clay et al. 2009). Mendoza et al. (2002a) conducted histological studies that reveal that the digestive tract is fully formed by 5 DPH, signaling the start of lecitho-exotrophic feeding. Complete exogenous feeding beings at 22 mm TL (Mendoza et al. 2002b).

Juvenile alligator gars range in total length from 98.0 to 117.0 mm (Simon and Wallus

1990).

Juvenile gars have distinctive irregular black stripes on the ventral sides and a whitish stripe bordered by dark lines extending from somewhat behind the origin of the dorsal fin to the snout (Ross 2001; Aguilera et al. 2011).

Age and growth

Female Alligator Gar exhibit larger maximum size and age than males; most literature indicates that females live an average of 50 years while males live an average of 26 years (Ferrara 2001; Boschung and Mayden 2004; Roberts and Harrel 2006;

Salnikov 2010). Some primary literature indicates that Alligator Gar live over 50 years

(Buckmeier et al. 2016). Growth is rapid in the first years of life before slowing as they age. By the first year of age Alligator Gar grow 25-30 cm (Salnikov 2010); it takes an average of 10 years to grow to 1 m, and 30 or more to grow to 2 m (Buckmeier 2008).

Until 10 DPH, larvae grow 1.5 mm/day, after 10 DPH growth rate increases to 5.06 mm/day until a total length of 50 mm is reached, generally around 15 DPH (Mendoza et al 2002a; Aguilera et al. 2011). By 30 DPH, the larvae are considered juveniles, they average 130 mm total length and no longer exhibit a dorsal line (Mendoza et al 2002a).

The average Alligator Gar grows up to 2 m TL and 45 kg; however, Alligator Gar have been reported up to 3 m TL and 160 kg (Suttkus 1963; Salnikov 2010). Personal correspondence (S.F. Hildebreans, F.A. Cook 1959) describes a 3.7-meter Alligator Gar caught in 1933 in Lake Washington, Mississippi (Ross 2001).

FishBase (Froese and Pauly 2018) estimates that resilience of the species is very low, with a minimum population doubling time of more than 14 years due to late sexual maturation. However, recent studies have indicated that coastal Alligator Gar in

Louisiana mature faster than literature suggests (Ferrara et al. 2015). Age of maturity

was determined from otoliths, inspection of gonads, and histological analysis from two southern Louisiana coastal populations. Ferrara et al. (2015) observed that females matured at 4-6 years but at slightly smaller sizes (1,100-1,400 mm TL) than inland females (11-14 years; 1,500 mm TL). Coastal males were also observed to mature earlier, at 3 years, but at similar sizes to inland Alligator Gar (1,000 mm TL; Ferrara et al. 2015).

Diet

Six to eight days after hatching larvae begin the transitional lecitho-exotrophic feeding stage, when larvae obtain nourishment from the yolk reserves and active predation of zooplankton and invertebrates (Mendoza et al. 2002a; Mendoza et al.

2002b; Aguilera et al. 2011). Exogenous feeding begins between 12.5 and 22.5 mm TL

(Clay et al. 2009). Mendoza et al. (2002a) conducted histological studies that reveal that the digestive tract is fully formed by 5 DAH, signaling the start of lecitho-exotrophic feeding. Complete exogenous feeding beings at 22 mm TL (Mendoza et al. 2002b).

Alligator Gar are described as an ambush predator and a scavenger (Froese and

Pauly 2018). They predominantly eat forage fishes; however, birds, invertebrates, and fishing tackle have been found in their stomachs (Buckmeier 2008). Prey size for

Alligator Gar is related to snout size (Mendoza et al. 2002b). While their diet varies considerably, it tends towards piscivory as body size increases (Echelle and Riggs

1972).

The size and shape of the Alligator Gar body and head is ideal for quick, short dashes and ambush feeding. Alligator Gar float motionless, often getting mistaken for branches or logs, until the gar performs quick lateral head movements, swallowing prey

whole (Mettee et al. 1996; Boschung and Mayden 2004). Brackish water Alligator Gar have been known to feed on blue crabs as well as fish, invertebrates, sea birds and other small mammals (Ross 2001; Froese and Pauly 2018). Studies have revealed that, while Alligator Gar are infamous for eating anything, most of their diet consists of

Gizzard Shad Dorosoma cepedianum, Threadfin Shad D. petenense, Golden Shiners

Notemigonus crysoleucas, and rough or coarse fish species (Schultz 2004). FishBase

(Froese and Pauly 2018) notes that the trophic level is 4.0 (± 0.67) based on food items, indicating a tertiary consumer.

Parasites and disease

The species is not susceptible to OIE reportable diseases (www.oie.int). Alligator

Gar are susceptible to pathogens including; Cestoda Proteocephalus ambloplitis,

Trematoda Clinostomum and Rhipidocotyle Lepisostei, Nemata Contracaecum spiculigerum and Dechelyne lepisosteus (Wardle 1990; Mayberry et al. 2000),

Crustacea Ergalis versicolor (Hoffman 1967; Hassan-Williams and Bonner 2013), and

Macroderoides texanus in Texas (Tkach et al. 2008). There is no indication in literature that these parasites are of concern in Florida (FDACS 2019b).

Control

Methods

Eradication efforts (e.g. dynamite and trapping; Scarnecchia 1992) and overfishing have been effective in reducing Alligator Gar populations in their native habitat (Buckmeier 2008). Alligator Gar spawning aggregations have been used to facilitate eradication efforts in the past (Scarnecchia 1992).

Controlling populations of Alligator Gar would be possible through harvesting, as harvesting over 6.5% of the population annually is estimated to be unsustainable (Smith

et al. 2017). Gill nets are commonly used by fishermen and scientists to collect Alligator

Gar in Mexico (Garcia de Leon et al. 2001) and the United States.

Case studies

Mutlak et al. (2017) states that there is no published information on the establishment of Alligator Gar outside of their native range. Thus, there are no case studies documenting the control of Alligator Gar.

While there are no case studies, there is some primary literature on eradication efforts to cull gar, including Alligator Gar, populations. Scarnecchia (1992) notes that methods include dynamite, particularly when the fish are congregated for spawning, was highly successful. Johnston (1961) was quoted “During one day's operation, over

3.5 tons of gar were removed.” Burr (1931) developed early methodology for eradicating gar through electrocution, after being shocked the gars would sink to the bottom and drown. Gar trapping devices that took advantage of the gar’s size and reduced flexion were used to trap and remove gar from river systems as well (Scarnecchia 1992).

Potential Florida Distribution

Hospitable Habitat

Florida has seemingly suitable habitat in coastal river systems along the northern

Gulf of Mexico coast east of the current range of Alligator Gar, including the Suwannee

River in Florida’s Big Bend. Many of these systems periodically flood surrounding hardwood forest, backwaters, and coastal marshes (SRWMD 2017), presumably suitable spawning and nursery habitat for Alligator Gar. Coastal rivers along the west coast of Florida likely vary in habitat quality for Alligator Gar, particularly in spawning and nursery habitat. With some exceptions, such as possibly the Peace River, most systems have relatively small floodplains and short periods of floodplain inundation.

Southern Florida has extensive wetlands that may prove suitable if Alligator Gar is capable of using canals, solution holes, and sloughs as refuge habitat during low water periods and successfully spawning and recruiting during high waters in flooded marsh habitat.

East coast habitats may prove suitable for Alligator Gar survival but have relatively few potential spawning/nursery areas. Inland areas of the Kissimmee River-

Lake Okeechobee system and the St. Johns River basin may have considerable suitable habitat depending on the ability of Alligator Gar to successfully spawn and recruit in more lentic systems. The Longnose Gar is a lotic spawner and successfully spawns and recruits in both systems (Holloway 1954; Gandy et al. 2012). However, this species spawns in channels rather than backwaters (Johnson and Noltie 1996).

Timing of flooding may be important, though Alligator Gar has an extended spawning period across its native range (January to September depending on region;

Time of Year, above).

Climate matching (CLIMATCH, Australian Bureau of Agricultural and Resource

Economics) of the native range of Alligator Gar and the risk assessment area of Florida shows a high climate match with a climate 6 score (Bomford et al. fish climate match paper) of 0.920 (Hill, unpublished data; Figures 3-11; 3-12). Suitable climate occurs throughout nearly all of Florida though the highest match occurs in the panhandle and northern Florida (Figure 3-12). Eastern Florida has a higher match than western or south Florida, with west-central Florida having the lowest match (Figure 3-12). The climate stations in the western panhandle with a similarity value of 10 are climate stations within the current Alligator Gar range (Figure 3-12). The climate matching

completed by the USFWS using RAMP is similar, though the pattern of highest match differs with higher match in portions of southwest and central Florida and lower match on the east coast (Figure 3-13).

Figure 3-11. Alligator Gar CLIMATCH source map (Hill, unpublished data).

Figure 3-12. Alligator Gar CLIMATCH target map in Florida (Hill, unpublished data).

Figure 3-13. RAMP (Sanders et al. 2014) map of climate match for Alligator Gar in the United States (USFWS 2017).

The Fish and Wildlife Service performed a climate match (Figure 3-13) for the contiguous United States resulting in a Climate 6 score of 0.328 (scores >0.103 are classified high) indicating a high climate match for the United States (USFWS 2017).

The climate match was high in the southeastern U.S., including peninsular Florida and

Texas. The climate match was performed with RAMP, a system that utilizes specific weather stations as sources for the climate match (Figure 3-14; USFWS 2017).

Figure 3-14. RAMP (Sanders et al. 2014) interpolated grid based on weather stations showing spots for climate locations estimated based on grid, climate locations estimated (red) and non-source locations (gray) for A. spatula climate matching (USFWS 2017).

The northern most native range of the Alligator Gar has reported temperatures as low as 1℃ and recorded highs of 30℃ (Salnikov 2010). Florida Springs average 22℃ year-round, well within the recorded thermal preferences for Alligator Gar. The Gulf

Coast of Florida has reported temperatures of 13℃ in January and 31℃ in August

(https://www.nodc.noaa.gov/dsdt/cwtg/all_meanT.html).

Ecologically similar species

Florida Gar, Spotted Gar, and Longnose Gar are also large-bodied, piscivorous fish that share habitat and food preferences with Alligator Gar. However, Alligator Gar is much larger as an adult than these three species. Spotted Gar and Longnose Gar naturally co-occur with Alligator Gar (Wegener 2018). Other relatively large piscivorous fish that inhabit Florida and would likely interact with Alligator Gar if this species were to establish within the state include Largemouth Bass Micropterus salmoides, Bowfin Amia calva, Flathead Catfish Pylodictis olivaris, Channel Catfish Ictalurus punctatus, and Blue

Catfish I. furcatus, plus some large euryhaline species such as Atlantic Tarpon

Megalops atlanticus and Common Snook Centropomus undecimalis. All these species naturally overlap with Alligator Gar somewhere within its native range.

Although Alligator Gar would overlap in habitat use with all these species to a certain extent, all these species also occur in habitats that would generally lack Alligator

Gar. Potential for competition among these species would hinge not only on the shared use of prey resources, but the limiting nature of these resources and their depletion dynamics.

Introduction pathways

The most common introduction pathways for Alligator Gar in the literature are aquarium release and deliberate release as a sport fish (USGS NAS 2019).

Release from captive populations

There is no commercial production of Alligator Gar in Florida; however, there is a research population at the University of Florida/IFAS Tropical Aquaculture Laboratory in

Ruskin. These fish are held under permit and the facility is permitted by the Division of

Aquaculture, Florida Department of Agriculture and Consumer Services (FDACS 2019) for containment of conditional, non-native species. The facility operates under mandatory Best Management Practices (BMPs) that includes provisions for containment of conditional and non-native species (FDACS 2019). The facility is regularly inspected for BMP compliance by FDACS. A recent evaluation of the Florida Aquaculture BMPs, including the facility holding Alligator Gar, showed effective enforcement and high levels of compliance with the conditional and non-native species provisions of the BMPs

(Tuckett et al. 2016).

If commercial aquaculture were allowed in Florida, all producers of Alligator Gar would be certified by FDACS and would have to follow mandatory Florida Aquaculture

BMPs. This program is designed, in part, to reduce the potential for escape of aquaculture stocks into the environment. Specific risk-mitigating practices can be incorporated into the BMPs or culture regulations for conditional species (e.g., Lates regulations; Hardin and Hill 2012).

Release of Alligator Gar into Florida as a sport fish is illegal without a permit from the Florida Fish and Wildlife Conservation Commission (Florida Administrative Code:

Chapter 68-5).

In the United States, aquarium release is a primary vector of introduction of non- native fishes. Aquarium release is cited as the most likely vector of individuals found outside of their native range, second is stocking. The large size of Alligator Gar (2-3 m) is likely the motivation for aquarium release as they quickly outgrow aquaria (i.e. tankbuster; Holmberg et al. 2015). In Florida, the single reported introduction was thought to have been an aquarium release (Fuller 2019). Under current regulations it is

illegal for the general public to possess Alligator Gar as an ornamental species (Florida

Administrative Code: 68A-27.005).

Direct importation

There is no federal regulation prohibiting direct importation of Alligator Gar into the United States and the species is cultured on fish farms in Asia. Importation, possession, and sale of Alligator Gar in Florida is currently restricted and allowed only under permit from FWC (FWC 2019b; Florida Administrative Code: 68A-27.005).

Incidental importation

There is no evidence of incidental importation of Alligator Gar. It is unlikely to be confused with other gar because juvenile and adult Alligator Gar are distinctive, and trade is restricted.

Range extension

There is no evidence of range extension for the Alligator Gar. While it has been reported and collected in multiple countries outside of its native range, there is no evidence of establishment outside of their native range

Potential Impact

Ecological

Potential to eliminate or significantly reduce native species

Although gar have long been thought to represent a threat to more desirable native species, thinking has shifted considerably in recent decades to a more balanced stance which views gar more similarly to other species in fish communities (Scarnecchia 1992).

Alligator Gar naturally overlaps in range with the predatory fishes it would encounter if it were to establish in other regions of Florida. Food competition might occur but the

effects of competition, if any, would hinge on the use of the resource, its limiting nature, and its depletion/production dynamics.

Predation on native fishes and other organisms may be a concern for such a large-bodied predator. Non-native Flathead Catfish has had large predatory impacts on the abundance of Redbreast Sunfish Lepomis auratus and two bullhead catfishes

Ameiurus spp. in Florida (Dobbins et al. 2012). Concerns over predation by the large- bodied Barramundi Perch Lates calcarifer contributed to a high-risk score for environmental impacts in a Florida risk assessment (Hardin and Hill 2012).

Nevertheless, the potential impacts of Alligator Gar on prey populations are less clear.

No populations of established, non-native Alligator Gar exist to determine if impacts have occurred. The few studies of re-introduced Alligator Gar suggest little evidence of competition or prey depletion. For example, diet studies in a re-introduced population in western Kentucky suggests opportunistic feeding behavior and a lack of diversity in abundant prey for four sympatric gar species (Richardson 2015).

There are concerns that hybridization with native gar species (Spotted Gar and

Longnose Gar) or between cultured and native Alligator Gar, may result in negative impacts and loss of adaptations of the native species currently within its native range.

Bohn et al. (2017) has documented hybridization between Alligator Gar and Longnose

Gar in the wild. Research suggests that the large size of female Alligator Gar make them attractive to other native gar species, potentially resulting in loss of genetic diversity and adapted traits specific to coastal or inland individuals (Wegener 2018). In aquaculture, fish from different sources (e.g. coastal vs inland) are recommended to be

separated reproductively by behavior as the estuarine (coastal) fish do not move far upriver (Buckmeier et al. 2013; Fernando et al. 2015).

Studies that are ongoing in Florida to assess if hybridization has occurred in

Pensacola Bay, Florida, between these species (Wegener 2018). Hybridization between

Alligator Gar and Longnose Gar has been documented in captivity and the wild

(Herrington et al. 2011; Bohn et al. 2017). Potential risks of hybridization if the Alligator

Gar were to establish in other regions of Florida would increase if the species would be more likely to hybridize within the new range. Of the two species that have hybridized with Alligator Gar in their native range, Spotted Gar does not occur naturally in Florida.

It is not known if the most common gar in the state, Florida Gar, can hybridize with

Alligator Gar.

History of range extension, high population growth rate, tendency to monoculture

Alligator Gar exhibit low population growth rates and the estimated population doubling rate is over 14 years (Froese and Pauly 2018) due to the late maturation of the species.

While there are Alligator Gar reported outside of the United States, there is no published information on Alligator Gar establishing populations outside of North America (Mutlak et al. 2017).

Alligator Gar exhibit no tendency to monoculture; adults can be found in small aggregations, as evidenced by the success of the use of the Judas technique to locate untagged adults in Alligator Gar telemetry studies (Wegener 2018); however, aggregations disperse during warmer seasons (Brinkman 2003; Wegener et al. 2017).

Potential to adversely impact listed species

Florida has few imperiled species that are likely to interact with Alligator Gar if this species were to establish populations outside its native range in Florida. Many listed fish species naturally overlap in range with Alligator Gar (e.g. Gulf Sturgeon Acipenser oxyrhynchus desotoi; Blackmouth Shiner Notropis melanostomus, Saltmarsh

Topminnow Fundulus jenkinsi).

Potential for habitat alteration

Alligator Gar are not known to alter habitats directly or indirectly.

Human Impact

Despite the intimidating size and sharp teeth of the Alligator Gar, there are no records of the Alligator Gar negatively impacting human health. Fishbase (Froese and

Pauly 2018) lists the Alligator Gar as harmless to human health. There are no documented attacks on humans and observations indicate that when disturbed by fishermen or swimmers, Alligator Gar swim deeper and away from contact (Suttkus

1963).

Alligator Gar meat is safe for human consumption; however, the eggs are toxic if ingested by mammals, reptiles, and crustaceans (Boschung and Mayden 2004;

Broussard 2009). While Alligator Gar are not known for presenting a danger to humans, handling them can result in injury due to their sharp teeth and head plates (Mettee et al.

1996). It is noted that Alligator Gar have potential to damage boats and fishing gear due to their large size and teeth (Scarnecchia 1992).

Economic

Biofouling

No evidence of biofouling in native range.

Competition with agriculture/cultured crops

No evidence of competition with agriculture or cultured crops.

Impact agriculture/cultured crops

No evidence of impacts to agriculture or cultured crops.

Socio-economic impacts

Positive socio-economic impacts of Alligator Gar result from ornamental sales through the aquaculture industry and the increased interest and market as a sportfish and for food. In Alabama and in the Rio Grande River there is a thriving recreational bow fishery for Alligator Gar (www.fws.gov). In Texas there is the belief that angling activity for Alligator Gar has increased (Buckmeier 2008). Guided gar fishing trips are valued up to $750 a day (www.reeis.usda.gov) and Alligator Gar meat is sold in the

French market in New Orleans, the southern United States (valued at $3/pound in

Arkansas), and Mexico (Suttkus 1963; Garcia de Leon et al. 2001; Buckmeier 2008).

Alabama Game and Fish Division also note a growing demand for Alligator Gar meat in the southeastern United States which has resulted in increased commercial fishing

(Mettee et al. 1996).

The impact of Alligator Gar to sportfish is negligible. In Texas, Alligator Gar have been found to benefit healthy sportfish populations by eating weaker fishes, increasing growth rates and stock health. In Texas, it was noted that lakes great for sportfishing have healthy Alligator Gar populations (Felterman 2015; https://tpwd.texas.gov).

The negative social perceptions of the species as a monster fish may result in management and removal costs if the species was to establish outside of its native range and was perceived to be a threat to humans.

Human Use

Aquaculture

Alligator Gar aquaculture has been successful due to the species high fecundity; broodstock can easily be maintained, readily spawn in captivity, can tolerate poor water quality, and can be reared entirely on an artificial diet (Weed 1923; Mendoza et al.

2002a; Mendoza et al. 2002b; Clay et al. 2009).

There is interest in Florida to culture Alligator Gar for food and out-of-state sale for the aquarium trade; however, the activity is not currently permitted. Scarnecchia

(1992) notes "the flesh of gars is not only edible, but highly palatable… compares favorably with the flesh of highly regarded game and food species." Biologists note there is a growing interest in Alligator Gar overseas for sport (Fuller 2019).

There is potential for culture of Alligator Gar for conservation and restoration.

There are currently three federal fish hatcheries culturing and producing young Alligator

Gar to supplement wild populations; the Private John Allen National Fish Hatchery

(Tupelo, Mississippi); Tishomingo National Fish Hatchery (Tishomingo, Oklahoma); and

Aquaculture Center ‘Tancol’, Tampico, (Tampaulipas, Mexico) (Buckmeier 2008,

USFWS 2016). The Warm Springs National Hatchery is part of the restoration efforts for the Mobile and Mississippi River drainage basins (USFWS 2014). The Natchitoches

National Fish Hatchery is working with the Private John Allen National Fish Hatchery and Tennessee Wildlife Resource Agency to produce Alligator gar to aid in developing a recreational fishery in west Tennessee (USFWS 2016).

Commercial value

Alligator Gar are highly desired in the aquarium trade in Asia, the value of an 8 foot Alligator Gar is reported to be $40,000 in Japan

(https://www.courthousenews.com/a-strange-case-a-strange-fish/). In 2003, commercial fisheries landings for gars in Louisiana (alligator gar, longnose gar, shortnose gar, and spotted gar combined) was valued at greater than $515,000 (LDWF 2005). In 2007, commercial anglers in Texas reported gar harvests of 1,000 lbs. or less (Buckmeier

2008). The average commercial harvest of alligator gar in Louisiana from 1999-2006 was 523,617 pounds/year and the 2003 commercial fisheries landings for gars (Alligator

Gar, Longnose Gar, Shortnose Gar, and Spotted Gar) was valued at greater than

$515,000 (LDWF 2005; DiBenedetto 2009). In Baton Rouge, Louisiana, at the local seafood market, gar filets sell up to $3/pound (Buckmeier 2008; DiBenedetto 2009;

Zullo 2009). Guided gar fishing trips can cost up to $750 a day (www.reeis.usda.gov).

The Aquaculture Center Tancol in Tampico, Mexico is producing Alligator Gar for food use (Buckmeier 2008). Suttkus (1963) writes that Alligator Gar meat is sold in the

French market in New Orleans and the southern United States. Alabama Game and

Fish Division note a growing demand for Alligator Gar meat in the southeastern United

States which has resulted in increased commercial fishing (Mettee et al. 1996). In

Florida, there is an interest in culturing Alligator Gar for food. Buckmeier (2008) addresses an article titled “Gar in the Pan” that notes that Alligator Gar meat sells for

$3/pound in Arkansas and was more popular than catfish. The FAO notes that there is aquaculture of Alligator Gar in Mexico, where it is highly valued as a food fish (Garcia de Leon et al. 2001; Buckmeier 2008).

Sport fishing for Alligator Gar has become popular in recent years in Louisiana,

Arkansas, Mississippi, and other states in the Mississippi Valley (Suttkus 1963), in

Alabama, Alligator Gar is a popular sport fish (Mettee et al. 1996). Mettee estimates that several hundred gars (species not specified) are harvested annually in Alabama for sport. In Alabama and in the Rio Grande River there is a recreational bow fishery for

Alligator Gar (www.fws.gov). In Texas, although there are no data to support it, there is the belief that angling activity for Alligator Gar has increased (Buckmeier 2008).

Conservation and Restoration

Supplemental stocking has been proposed as a conservation measure to supplement or reintroduce Alligator Gar within their native range (Barnett et al. 2011;

Perschbacher 2011). Precautions are taken in hatchery management to prevent mixing broodstock from distinct populations and losing population adaptions as a result of inbreeding (Fernando et al. 2015).

The Private John Allen National Fish Hatchery in Mississippi serves as the Fish and Wildlife Service’s lead for restoring Alligator Gar in the Southeast United States by providing juveniles for stocking efforts in Tennessee, Kentucky, Missouri, Kansas, and

Illinois (www.fws.gov). Warm Springs National Fish Hatchery in Georgia, in association with hatchery services, provides continuing research in genetics, development of intensive culture and production techniques, stocking support, and tagging/marking to aid in Alligator Gar conservation efforts (USFWS 2016). The Tishomingo National Fish

Hatchery in Oklahoma set a record for Alligator Gar growth and production; the gars were transferred to Missouri to be stocked for conservation (USFWS 2016).

Research in Florida to provide better provide population estimates and movement and habitat use is continuing to allow for better management regulation reflective of the population status in the state. There has been research in tagging individuals to better understand habitat use and movement, as well as better estimate population size in Florida. In Florida, genetic studies to determine if genetic variation events have occurred between gar species and Alligator Gar in the past.

Research

Current research encompasses federal and state agencies, universities, and departments that study movement and habitat use, reproduction, biology, aquaculture, and restoration efforts. Ongoing research efforts and facilities are noted on the Southern

Division American Fisheries Society Alligator Gar Technical Committee website

(https://units.fisheries.org/sdafsalligatorgarcommittee/research/).

Figure 3-15. Bar chart of Alligator Gar literature produced from 1990-2018. Photo courtesy of author (Web of Science).

Historic Use

Alligator Gar were used for meat and tools; the scales were used by Native

Americans for as arrowheads, jewelry, and other instruments. Gar skin was used for

leather and by farmers to cover their wooden plowshares (Weed 1923; Scarnecchia

1992; Schultz 2004). Stuffed gars were noted in literature to be given as gifts (Boschung and Mayden 2004; Salnikov 2010).

Social

Alligator Gar were historically viewed as “weeds and wolves among fishes” and students were taught that gars made nuisances of themselves by becoming entangled in nets. Under (repealed) Iowa statutes, it was not legal to release the gar alive

(Scarnecchia 1992). There is now a more positive perception of the species due to its value as sport and food fish (Sutton 1998).

There has been positive publicity as possible means to control Asian carp;

Michigan Sea Grant writes that while the Alligator Gar is not the only solution, they would likely take advantage of the abundance of carp in the Mississippi River and

Illinois River which would help reduce Asian Carp populations (MSU 2016). Other articles titled “How to combat Asian carp? Get an Alligator Gar” (www.latimes.com) and

“Conservation of Ancient Fishes: Reintroducing the Alligator Gar; and What About

Those Carp?” (https://blog.nationalgeographic.org) briefly discuss the positive impacts.

While these articles do not discuss that Alligator Gar are not the only solution, they reflect a more positive social view of Alligator Gar than historically seen.

In Hong Kong, Alligator Gar were reported in a public pond because park visitors feared for their safety (https://news.abs-cbn.com). Individuals unaware of the Alligator

Gar’s diet may find the presence of Alligator Gar distressing, resulting in negative publicity. A National Geographic article (https://www.nationalgeographic.com) describes characteristics of Alligator Gar as “menacing looking behemoth” and “prehistoric mega

fish with a tooth filled mouth and broad alligator like head”, which would be intimidating to the public. The intimidating presence of the fish has been reinforced by popular television shows such as “River Monsters” that had an episode on Alligator Gar. The episode description describes the species as a “fish reputed to have committed a series of violent attacks on humans, said to be as vicious as a shark and as big as a gator.”

The large size of the Alligator Gar can be intimidating, but Scarnecchia (1992) attributes the large maximum size and distinctive characteristics to have helped the

Alligator Gar become more desirable as a trophy fish. Increased interest in angling for

Alligator Gar and better understanding of the role Alligator Gar provide in aquatic ecosystems (Ross 2001) have resulted in efforts to actively manage and provide more information on Alligator Gar populations and behavior.

Legal

In Florida, a closed harvest on Alligator Gar was enacted in 2006, making it illegal to take or possess Alligator Gar without scientific permits (FWC 2019b).

Tennessee is restocking fish and does not allow harvest (Buckmeier 2008) and

Oklahoma has closed a known spawning area for fishing during spawning season.

Several additional states are stocking or considering stocking Alligator Gar.

Seven states have imposed fishing regulations that restrict or prohibit harvest

(Binion et al. 2015). Harvest regulations vary by state, bag limits are as follows:

Alabama (1/day); Arkansas (2/day); Florida (harvest prohibited), Mississippi (2/day);

Texas (1/day), and Oklahoma (1/day) (DiBeneditto 2009). The state of Louisiana has no bag limit, size limit, commercial license limitations, or closed season regulations

(Ferrara 2001; DiBeneditto 2009).

Conservation Status

In 2006 Florida Fish and Wildlife Conservation Commission (FWC 2019b) implemented a harvest closure in response to limited data regarding native Alligator Gar populations. It is also illegal in Florida to take or possess an Alligator Gar without a permit. Florida Fish and Wildlife Conservation Commission will issue permits for scientific research and management efforts (FWC 2019b).

Risk Screening

The mean FISK score for Alligator Gar was 4, with a low individual score of 3 and a high score of 5 (Table 3-1). All scores are on the lower end of medium risk (non- invasive) given a calibrated non-invasive/invasive threshold value of 10.25 for peninsular Florida (Lawson et al. 2015).

Alligator Gar have no history of establishment outside of their native range and a low average score for undesirable traits (Figure 3-17); if these characteristics are present, they increase FISK score as they are traits of invasive species. The lack of establishment, despite introduction, and few undesirable traits contribute to the lower

FISK risk level. Salinity tolerance (35 ppt; Suchy 2009; Green et al. 2015) and lack of data for minimum population size to maintain a viable population are undesirable traits that increase the FISK score. The lack of invasion history and undesirable traits contributed to the mean score of 4 for the FISK risk screening of Alligator Gar aquaculture in Florida.

The main factors that increased the score were high climate match, introduction of individuals outside the native range, large body size, high salinity tolerance for dispersal, ability to breathe air, potential for hybridization with native species, potential

for humans to illegally stock this species, wide dispersal and movement of adults, and resilient physiology (Table 3-2). Factors that decrease the overall score included the lack of establishment history outside of the native range, lack of impacts in introduced populations, lack of invasive relatives, lack of OIE-reportable pathogens, presentation of no threat to human health, no parental care, and long generation time (Table 3-2).

Assessors indicated similar overall certainty levels, with assessor one at 0.79, assessor two at 0.84, and assessor 3 at 0.75. The overall certainty level is computed by the FISK software from certainty responses. The certainty level corresponds to the confidence level that the assessor associated with the risk response (FISKv2 2013).

The confidence level is indicative of the level of certainty (or uncertainty; Copp et al.

2009), with the index ranging from a low of value 0.25 to a high value of 1 (Almeida et al. 2013; Vilizzi and Copp 2013). Certainty can be influenced by the quality of literature available, tool guidance, and the risk tolerance and experience of the assessors.

While overall certainty was similar for all three assessors, there was some variation in certainty among all assessors over the 49 questions of the Alligator Gar

FISK risk screening (Figure 3-2). Assessor two had no ‘very uncertain’ classifications on the overall risk assessment, while assessors one and three respectively had 2 and 3 responses marked as ‘very uncertain’. In the overall assessment, there were very few responses among all three assessors that were marked as ‘very uncertain’. The highest level of certainty (0.84) was associated with assessor two, who also had the highest level of ‘very certain’ responses. Assessor three had the lowest overall certainty level and exhibited the lowest number of ‘very certain’ responses for the risk screen, with

18% fewer ‘very certain’ responses than assessor two and 10% fewer than assessor one.

The review process did not change the mean scores and only a minor change was made to the overall certainty of one assessor. There was a four-point difference in the answers to both the biogeography and biology/ecology sections questions, with persistence attributes having the most disagreement (five-point difference). The overall certainty of the assessors was similar, with the least experienced assessor having the lowest certainty. After review, this assessor adjusted the certainty upwards slightly

(+0.05). The justifications and responses of each assessor were generally in agreement with only one unclear question response (6.05). The major differences in answers stemmed from differing interpretation of the data. For example, Alligator Gar are air breathers. Two assessors interpreted this as enough evidence for it to be able to survive out of water, while one assessor did not (question 4.09). Answers to question

8.04, about the species benefiting from disturbance, differed as well. One assessor provided flooding as a benefit while the other two provided dams as an impediment to

Alligator Gar spawning. Additionally, there was disagreement in responses to question

6.03 (about hybridization potential) based on the interpretation of the limited information available about hybridization of this species. Incomplete data also affected the responses to question 5.01 (about adverse foraging effects) with all assessors answering differently with varying levels of uncertainty. Overall, the assessors and reviewer agreed with the FISK results, with data deficiency and interpretation explaining the differences in responses.

The FISK risk screen score indicated that further, comprehensive risk assessment needed to be performed to more accurately assess the risk of Alligator Gar aquaculture in Florida.

Generic Analysis

Stakeholder Workshop and Generic Analysis

The stakeholder workshop was attended by eight of the eleven stakeholder panel members. The stakeholder qualitative assessment utilized the biological synopsis, FISK risk screenings, and the expertise of the stakeholder panel to perform the comprehensive risk assessment suggested by the FISK risk screen. During the initial discussion sessions prior to the qualitative assessment, the panel posed the question of if there was enough expertise to be able to perform this assessment. Following discussion, the panel concluded that the panel was trained and knowledgeable enough to complete the Generic Analysis. The conclusion was reiterated in the post workshop evaluation, where 100% of respondents felt the panel represented an appropriate composition of expertise and backgrounds.

Breakout groups were utilized to facilitate initial discussion of questions regarding the probability of establishment and the impacts of establishment. Breakout groups were unable to come to a complete consensus on risk levels for consequences of introduction or establishment, resulting in multiple risk levels and associated certainty.

Each breakout group resulted in an overall probability of introduction, consequences of establishment, and overall risk potential. The average risk level for probability of introduction was medium for group 1 and low-medium for group 2. The overall risk level for consequences of establishment was the same for each respective group, both groups averaging medium. The overall risk potential for each breakout group was

medium, consistent with the overall group’s overall risk potential (ORP). Medium risk in the Generic Analysis indicates that the organism is of moderate concern and that risk mitigation is justified (ANSTF 1996).

The breakout groups gave consistent risk ratings for the presence in the pathway and introduction, high risk, with varying certainty (Table 3-3). Group 1 was more certain that Alligator Gar would be in the pathway while Group 2 had variation in certainty at the extreme ends of each spectrum. Some members of Group 2 were very certain that

Alligator Gar would be in the pathway as there is are already an ornamental wholesale pathway in Florida as well illegal sales. Colonization potential was also ranked similarly between the groups, with medium or low-medium, but with similar low certainty (VU and

RU). Spread potential results differed among the groups despite the rating listed as the same, medium. Group 1 had the highest variation (low and high) and somewhat less certainty (RU and MC). The two groups differed slightly in the overall risk rating for establishment, with Group 1 rating medium and Group 2 a low-medium.

There were greater differences in results for environmental impacts between the two breakout groups, with Group 1 rating medium risk and Group 2 rating low and medium for an overall low-medium (Table 3-3). Certainty also varied, ranging from VU to RC. Economic impacts were rated similarly (M for Group 1 and L-M for Group 2) with some variation in certainty. Group 1 rated the social/political impacts low (and VU) while

Group 2 ranked impacts higher (L-M and M), but with higher certainty (MC and RC).

The overall risk rating for impacts for both groups was medium. Combining the averages of both groups ratings resulted in the same medium overall risk potential outcome regardless of which group combinations were used.

The group discussion largely mirrored the breakout groups, with slight differences that suggested somewhat lower perceptions of risk, though certainty remained the same or decreased slightly (Table 3-3). The group concluded that risk of presence in the pathway and introduction risk were both high and, for this element, certainty increased overall (RC and VC). The group ratings and certainty for colonization were nearly identical to the results from the breakout groups (M), with a slight increase in certainty. Spread risk was also similar among the overall group and breakout groups at medium. The overall risk of establishment was the lowest of the four ratings (L).

Environmental and economic risks were rated by the group as medium, with a spread in ratings from low, low-medium, and medium with low certainty (RU) for environmental impacts and higher certainty (MC) for economic impacts. The social/political risk rating was low-medium, with a decline in overall certainty to reasonably uncertain. The ORP, using medium for establishment and medium for impacts/consequences, was medium. Medium indicates that Alligator Gar is of moderate concern, and risk mitigation is recommended.

Several topics arose during the breakout groups and overall group discussion.

Topics important for establishment and spread included risks of introduction from the pathways, reproductive requirements, the reproductive status of potential brackish water populations, lack of establishment outside of the native range despite introductions, and the lack of natural spread east and south beyond the western panhandle. Topics related to the consequences of establishment were predation impacts directly on native species and indirectly through competition for resources, hybridization with native gars, genetic

interactions with native Alligator Gar, and potential economic impacts of control programs for a cryptic species. Potential benefits of Alligator Gar culture were also discussed, with economic benefits from culture and trade, increased biosecurity resulting from decreased illegal trade and introduced diseases, potential to reduce illegal trade, increased research of captive stocks, and increased awareness of an imperiled, native species.

Some stakeholders expressed concern that a risk assessment was unnecessary or counterproductive. Comments solicited from stakeholders after the workshop addressed this point: “FWC’s webpage highlights the historic and declining range of alligator gar and details the need for conservation of this species. Alligator gar is a native species to Florida so a risk assessment to investigate the risk of colonization or range expansion seems counterproductive when the species has not spread, and considerable research and funds are being spent to conserve the species in Florida.

Aquaculture can provide valuable insight into the reproductive biology and habits of fish to inform conservation efforts.”

During breakout and group discussions, the panel considered the risk of introduction of Alligator Gar high. The certainty for this question was mostly moderate. A discussion of risk mitigation took place at the end of the workshop, with panel member’s opinions regarding the effectiveness of the Florida aquaculture BMPs as risk mitigation solicited. The panel generally agreed that current regulations and practices were sufficient to mitigate risk if containment, record keeping, and enforcement of these practices were raised to be equivalent to species on the conditional, non-native species list. During this conversation, concern was expressed again for potential internet pet

sales that may be released in Florida, with the panel acknowledging that this was an inevitable risk whether culture was permitted or not. Concerns for introduction in the St.

Johns watershed were noted, as there would be no barrier to prevent Alligator Gar spreading north to Georgia. Appropriate site location for aquaculture facilities was discussed to mitigate this concern.

The reproductive requirements of Alligator Gar and the Florida regions where conditions would be suitable was a topic repeated throughout the workshop. Literature provides little indication of the potential for Alligator Gar to spawn and recruit in other aquatic habitats and high environmental specificity for successful spawning and recruitment. The occurrence of rare volitional spawning of various gar species in captivity as well as volitional spawning in earthen ponds (Patterson et al. 2018) led to questions regarding the ability of Alligator Gar to spawn and recruit in the rivers, lakes, and marsh systems that make up peninsular Florida. Additionally, frequent discussion focused on the population of Alligator Gar that remain in brackish water bays and marshes of the native range, that potentially spawn in tidal creeks or other areas with freshwater inflow. Panel members speculated that these populations may be able to spawn in estuarine conditions, however, little is known about the prevalence, biology, or ecology of these populations, especially in Florida.

Several panel members noted the lack of successful invasion history of Alligator

Gar in discussion, particularly in reference to the lack of movement into peninsular

Florida. The native range of Alligator Gar extends south into Mexico, further highlighting questions as to why Alligator Gar have not occupied similar latitudes in Florida. The high salinity tolerance of adults and considerable migration and movement potential of

adults also made this discussion a highlight for future research and questions of invasion potential. Habitats east of the current Alligator Gar distribution appear suitable for the species, yet there is no evidence of the presence of Alligator Gar historically or currently in the area beyond occasional sightings. The panel and project team are unaware of any specific barrier that is preventing Alligator Gar from spreading naturally east in the panhandle or south into peninsular Florida. This issue was important for several panel members, who viewed this element as a telling characteristic of the reduced potential for establishment outside of the native range in Florida.

Many panel members felt that predation impacts were medium risk in breakout groups but changed the risk ranking to low or low-medium in the overall group discussion, with some maintaining medium risk level. Alligator Gar is a large, piscivorous predator, however, the panel noted that there was a lack of evidence for clear predation or competition effects within the native range or where the species has been re-introduced.

Hybridization was a primary concern and discussion point throughout the workshop, with impacts to native gars, especially Longnose Gar a considerable concern for some panel members. Some panel members consider this a minor issue, as

Alligator Gar in the panhandle coexist with Longnose Gar naturally. There was relatively little concern from the panel for potential genetic exchange between wild and cultured

Alligator Gar, but this risk was not unimportant. One panel member discussed that suspected hybrids had been found in Florida, and that genetic samples were collected.

There is currently no evidence to confirm hybridization in Florida. This concern is not more alarming due to the common practice of stock enhancement and reintroduction

programs by federal and state agencies in many parts of the historic native range of

Alligator Gar (e.g. Texas, Illinois, Kentucky).

The primary economic cost associated with establishment of Alligator Gar discussed by the panel was potential control costs. There was some disagreement among the panel if the state (FWC) would attempt to control the species and, if so, what the cost of control would be. It was noted that while Alligator Gar are large, they can be cryptic in a large system, increasing the control costs as they would be more difficult to find, capture, and remove. The preliminary difficulties encountered by researchers in

Florida finding and collecting Alligator Gar was discussed in support of the difficulty, time, and cost that would be associated with removal efforts. The panel agreed that costs could be high, upwards of $1,000,000 should control efforts be attempted for a large, interconnected system. Social impacts of the release of a large, predatory fish were also connected to higher control costs. Social impacts were also observed to be low by some panel members, as Alligator Gar are not highly visible in large systems, reducing the social impacts. Conversely, several panel members noted that controlling populations through increased harvest pressure would likely result in reduced potential economic costs as Alligator Gar appear highly susceptible to exploitation.

The direct and indirect benefits of permitting commercial Alligator Gar culture included economic gains accrued by individual fish farms and the aquaculture industry.

Industry representatives stated that only five to six ornamental farms have the technical ability and space to raise Alligator Gar for ornamental trade, with even fewer (two to three) interested in culturing them until the market was more developed. The sale of

Alligator Gar would likely be profitable for ornamental farms, with more time needed to

develop broodstock, saleable inventory, and markets for food production of Alligator

Gar. Other potential benefits to the state include a large, easily obtained supply of juvenile Alligator Gar for stock enhancement or reintroduction programs as well as considerable research on the reproduction and behavior of Alligator Gar in captivity.

Additionally, stakeholders commented that the increased presence of Alligator Gar in trade and on local farms may increase awareness of an imperiled, native species, and provide an example of a native fish in aquaculture.

Alligator Gar are currently produced on farms in Southeast Asia (personal communication Craig Watson, University of Florida) and shipped live to consumers. A legal, healthy, and inspected stock of ornamental Alligator Gar in Florida may replace this trade and would improve biosecurity for cultured fishes as well as wild stocks in

Florida.

Stakeholder Workshop Evaluation

Results of anonymous evaluation were positive (Table 3-4), with all participants providing the highest possible rating for panel composition and solicitation of input along with categories addressing communication, participation, and interaction of the panel and project team members. High scores were given for communication of objectives and ability to capture panel feedback, with the panel found useful by all respondents.

The overall meeting was rated good to excellent with all respondents stating they would attend a meeting of this type in the future.

Optional comments on ways to improve the meeting were included at the end of the survey, with three participants electing to provide feedback. Two participants commented that adding more time would be beneficial and allow for more discussion.

There were multiple comments that the panel was very informative and organized well,

with a good variety of stakeholder interests and backgrounds represented. One participant commented that, while the facilitator did a good job, having a completely impartial facilitator may be beneficial for separating facilitation and discussion, as well as would reduce the potential of conflicts of interest.

Table 3-1. FISK scores for three assessors of Alligator Gar aquaculture in Florida (mean = 4; Δ = 2). The score is the overall score of each assessor, with the overall scores the sum of the scores in each section (Biogeography/Historical (1.01 to 3.05) and Biology and Ecology (3.01 to 8.05)). Scores <1 indicate low risk, scores ≥ 1 and ≤10.25 indicate medium risk (Lawson et al. 2015).

Variable Assessor 1 Assessor 2 Assessor 3 Score 5 4 3 Risk Category Medium Medium Medium Biogeography/Historical -1 3 0 1. Domestication/Cultivation 0 2 1 2. Climate and Distribution 1 1 1 3. Invasive Elsewhere -2 0 -2 Biology and Ecology 6 1 3 4. Undesirable Traits 3 2 3 5. Feeding Guild 2 0 0 6. Reproduction -2 1 -1 7. Dispersal Mechanisms 0 0 0 8. Tolerance and Attributes 3 -2 1

Figure 3-16. Distributions of certainty percentage for the answers to 49 questions of the FISK risk screening by three assessors (Assessor 1 [blue bars], Assessor 2 [orange bars], and Assessor 3 [gray bars]) for Alligator Gar aquaculture in Florida. X-axis abbreviations are as follows: VU = very uncertain, MU = mostly uncertain, MC = mostly certain, and VC = very certain.

Table 3-2. FISK version 2 assessment for Alligator Gar for Florida. The Q ID column corresponds to question identification codes in FISK. Answer codes are N = no, Y = yes, and ? = don’t know and are separated to show answers, justification, and certainty of the two independent assessors. Certainty codes are 1 = very uncertain, 2 = moderately uncertain, 3 = moderately certain, and 4 = very certain.

Q Question Answer Justification Certainty ID 1.01 Is the species N Cultured by agencies for stock enhancement in a few 3 highly states and some culture as an ornamental in SE Asia but domesticated not widely cultivated. or widely Y There is no indication that the taxon has been grown 3 cultivated for deliberately for at least 20 generations, however, commercial, Alligator Gar are known to be easily reared in captivity to angling or provide broodstock for angling and restoration in several ornamental federal hatcheries in the US. Broodstock are easily purposes? maintained and spawn readily in captivity (Mendoza et al. 2002). Y It is not clear whether this species is highly-domesticated 3 and reared for 20 generations, which would extend back at least 60 years. However, Chong et al. (2010; Journal of Fish Biology) indicate that Alligator Gar are cultivated in Malaysia. Patterson et al. (2018; North American Journal of Aquaculture) report on Alligator Gar volitionally spawning in small aquaculture ponds designed for small ornamental fish. 1.02 Has the N No evidence of establishment outside native range 3 species (USGS NAS; FishBase) established N While the species has been identified in several 3 self- countries outside of its native range, there is no sustaining indication that the species is establishing self sustaining populations populations where introduced. The propagule pressure where is likely low where introduced (Scarnecchia 1992), but introduced? the status of some of the introduced populations is "uncertain" leading to lack of certainty ? There are numerous records for Alligator Gar, including 3 Texas in the USA and globally in Malaysia, Thailand, Iraq, and Indonesia. Fishbase indicates introductions to Hong Kong and Malaysia, but also indicate that it is not known whether they are established (https://www.fishbase.se/Introductions/IntroductionsList).

1.03 Does the N No evidence of this and no established populations. 3 species have N There is no indication in literature of the species having 3 invasive invasive races/varieties races/varietie N No evidence for invasive races, as likely none have been 4 s/subspecies produced. ?

Table 3-2. Continued

2.01 Is the species 3 High climate match from CLIMATCH software for Florida 4 reproductive (see report). tolerance suited to 3 The CLIMATCH software resulted in climate 6 score of 4 climates in 0.92 (scores over 0.103 are high) for Florida (see report) the risk assessment (1-low, 2- 3 The Climate 6 score for the potential non-native range in 4 medium, 3- Florida was calculated to be 0.92, a high climate match high)? using Climatch.

2.02 What is the 3 CLIMATCH climate matching program 4 quality of the climate 3 The native range of Alligator Gar (southeastern US) is 4 match data well researched and supported in primary literature (1-low, 2- medium, 3- 3 Alligator Gar have a well-known distribution in the 4 high)? southern US.

2.03 Does the N Koppen-Geiger publication by Peel et al. 2007 4 species demonstrate N Alligator Gar are confined to Cfa (Koppen-Geiger 4 broad climate publication by Peel et al. 2007) suitability? N Alligator Gar are largely confined to Cfa (warm 3 temperate; fully humid; hot summer).

2.04 Is the species Y Alligator Gar is native to a small portion of the RA in NW 4 native to, or Florida and naturally occurs in similar climate to a large has portion of the RA. (Biological Synopsis and Peel et al. established 2007) selfsustaining populations Y Alligator Gar native range in the Florida panhandle 3 in, regions corresponds to the Cfa area that encompasses most of with similar the RA area (peninsular Florida). The southern tip of climates to Florida is part of the RA area and not within the Cfa the RA area? range of climate.

Y The Cfa climate region extends south in Florida 4 approaching Naples on the west coast and Jupiter on the east coast.

Table 3-2. Continued

2.05 Does the Y Some instances of single specimens collected outside 4 species have native range (USGS NAS, FishBase) and some stocking a history of in SE Asia as a sportfish. being Y Yes, there are multiple reports documented where the 4 introduced species has been recorded outside of its native range outside its (Malaysia, Hong Kong, cultured in SE Asia; Biological natural synopsis) for sport and ornamental interests. range? Y USGS NAS 4 (https://nas.er.usgs.gov/queries/factsheet.aspx?SpeciesI D=755) indicates nonindigenous occurrences in California, South Carolina, and Texas. The species has also been reported from the east coast of Florida. Chong et al. (2010; Journal of Fish Biology) also reports the Alligator Gar from Malaysia and Fishbase (Froese and Pauly 2019) list Hong Kong and Malaysia as sites of introduction.

3.01 Has the N No known established populations (USGS NAS, 3 species FishBase) established one or more selfsustaining N There is no indication of the species establishing one 3 populations self sustaining population, so more is not likely. The beyond its status of the Alligator Gar found outside of their native native range? range is extirpated, not reproducing, or unknown

? Noted from Malaysia, Thailand, Iraq, and Indonesia. 4 Fishbase indicates introductions to Hong Kong and Malaysia, but also indicate that it is not known whether they are established (https://www.fishbase.se/Introductions/IntroductionsList. php?ID=1073GenusName=Atractosteus&SpeciesName =spatula&fc=34&StockCode=1089).

3.02 In the N No established populations. 3 species’ introduced N There is evidence that, while the species is mostly 2 range, are piscivorous, the majority of its diet is made of rough there impacts fishes. It has been established that Alligator Gar are not to wild stocks voracious predators of game fish or commercial species of angling or commercial species? N No known impacts to wild stocks of angling or 3 commercial species; this species has no verified non- native populations that are self-sustaining.

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Table 3-2. Continued

3.03 In the N No established populations 3 species’ introduced range, are N There is little information on impacts recorded in the 3 there impacts species introduced range as they have not been to established outside of their native range aquacultural, N No known introduced populations which are self- 4 aquarium, or sustaining; thus no known impacts, where the Alligator ornamental Gar would be unlikely to interact with aquacultural or species? ornamental species 3.04 In the N No established populations. 3 species’ introduced N There is little information on the species in its introduced 3 range, are range, there is no indication that the species has an there impacts impact on rivers, lakes, or amenity values in the native to rivers, range lakes or amenity N No evidence for impacts to rivers, lakes, or amenity 3 values? values. 3.05 Does the N The congeners Tropical Gar A. tropicus and Cuban Gar 3 species have A. tristoechus are not known to be invasive. No invasive Lepisosteus gar known to be invasive. congeners? N There is no indication of invasive congeners in literature 4 N There are two related species, Cuban Gar Atractosteus 4 tristoechus and Tropical Gar Atractosteus tropicus, both of which do not have known introductions according to Fishbase (Froese and Pauly 2019).

4.01 Is the species N Not poisonous/venomous. No known threat to human 3 poisonous/ve health. Gar eggs are toxic if eaten (Fuhrman et al. 1969). nomous, or Fuhrman, F.A., Fuhrman, G.J., Dull, D.L. and Mosher, poses other H.S., 1969. Toxins from eggs of fishes and Amphibia. risks to Journal of Agricultural and Food Chemistry, 17:417-424. human health? N The species is not poisonous or venomous to human 3 health, the large size is intimidating but there is no record of the species being harmful to human health. There are indications that the species is more inclined to avoid human contact. The eggs of the Alligator Gar are toxic to mammals (Boschung and Mayden 2004) N While the Tropical Gar is considered poisonous to eat 4 (Froese and Pauly 2019), the Alligator Gar is not considered venomous, poisonous, or a risk to human health, River Monsters, notwithstanding (http://www.animalplanet.com/tv-shows/river- monsters/fish-guide/alligator-gar-texas-usa/).

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Table 3-2. Continued

4.02 Does the N No established populations and thus no evidence of this. 1 species out- N There is no indication in literature of this, there is 3 compete with evidence that Alligator Gar feed mostly on rough fishes native and little on game species. Felterman (2015) found that species? Alligator Gar were beneficial to sportfish populations which could be indicitive of the relationship with native species. Texas Parks and Wildlife Department state that water with healthy Alligator Gar populations have healthy sportfish populations. Scarnecchia (1992) views Alligator Gar as a natural species in the ecosystem community N No evidence for competition with native species. 3 4.03 Is the species N Not a parasite. 4 parasitic of N There is no indication that the species is parasitic of 4 other other species in literature species? N No evidence for the Alligator Gar being parasitic of other 4 species. 4.04 Is the species N Humans fish for Alligator Gar, resulting in many declining 4 unpalatable and imperiled populations (Scarnecchia 1992; to, or lacking, Buckmeier 2008). Small juveniles likely vulnerable to a natural wide range of predators. predators? N Alligator Gar have few natural predators, especially 2 beyond the larval stage as they grow quickly. Their meat is safe for consumption but the eggs are toxic to mammals, reptiles, and crustaceans (Boschung and Mayden 2004; biological synopsis) and the only noted natural predators are humans and alligators (Ross 2001) N Human harvesting can lead to an unsustainable 4 population if harvest exceeds 6.5% (Smith et al. 2017; Transactions of the American Fisheries Society). Further, natural predation is likely, at least up to a certain size. 4.05 Does the N Florida has other large predatory fishes (e.g., Common 3 species prey Snook Centropomus undecilmalis, Atlantic Tarpon on a native Megalops atlanticus; Longnose Gar Lepisosteus species osseus). Otherwise, this species is unlikely to occur in previously habitats in close proximity to imperiled species. subjected to N Florida has large predatory fishes and there is literature 1 low (or no) on the beneficial effect of Alligator Gar on native predation? sportfish populations or commercially important native fish (TPWD; Scarnecchia 1992; Felterman 2015) N The question help suggests the species should be likely 4 to establish in a system where fish are likely to be absent; however, Alligator Gar inhabit large systems such as bayous, swamps, rivers, etc.., locations which are unlikely to be fishless.

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Table 3-2. Continued

4.06 Does the N No OIE-listed notifiable pathogens (OIE) 3 species host, N There is no indication in literature, no OIE listed 3 and/or is it a pathogens vector, for N There are no known OIE reportable diseases of the 3 one or more Alligator Gar; further, with close proximity to the risk recognized assessment area, non-native infectious agents are nonnative unlikely. infectious agents? 4.07 Does the Y Maximum length about 3 m and commonly up to 2 m 4 species (FishBase) achieve a large ultimate Y The species does achieve a large ultimate body size 3 body size (3m), as ornamental species the large size may make it (i.e., >15 cm more likely to be abandoned. total length) (more likely to be Y Fishbase (Froese and Pauly 2019) indicate a maximum 4 abandoned)? length of 305 cm. 4.08 Does the Y Adults survive in 35 ppt sea water (Suchy 2009; Green 4 species have et al. 2015). Juveniles and larvae are less tolerant of a wide elevated salinity (Schwartz and Allen 2013; Green et al. salinity 2015). tolerance or Y The species has a salinity tolerance of 35 ppt (biological 4 is euryhaline synopsis) but no euryhaline life cycle stage at some stage of its Y Juveniles can tolerate salinity at 24 ppt for 30 days 4 life cycle? (Schwarz and Allen 2013; Comparative Biochemistry and Physiology), but larvae exhibit lower tolerance (8 ppt). Adults can tolerate salinity at 35 ppt (Buckmeier 2008; https://tpwd.texas.gov/publications/nonpwdpubs/media/g ar_status_073108.pdf). 4.09 Is the species Y Air-breather (Omar-Ali et al. 2016). Omar-Ali, A., 4 able to Baumgartner, W., Allen, P.J. and Petrie-Hanson, L., withstand 2016. Fine Structure of the Gas Bladder of Alligator Gar, being out of Atractosteus spatula. Int. J. Sci. Res. Environ. Sci. water for Toxicol. 1:1-8. extended Y There is no literature on the ability of the species to 2 periods (e.g., withstand being out of water for extended periods, minimum of however, anecdotal evidence and tagging processes one or more (Wegener 2017;2018) indicate some ability to withstand hours)? being out of water for periods of time N No evidence for Alligator Gar exhibiting desiccation 3 tolerance.

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Table 3-2. Continued

4.10 Is the species N Mostly occurs in sluggish rivers and streams and their 3 tolerant of a backwaters (Biological Synopsis). range of water velocity N Alligator Gar exhibit preferences for slow moving rivers 3 conditions and oxbows, however, they have found that there are (e.g., distinct populations that also exhibit preferences for versatile in estuarine bays compared to rivers and oxbows habitat use) N Alligator Gar exhibit a preference for lower to moderate 2 flowing water (Kluender 2016; Ecology of Freshwater Fish). 4.11 Does feeding N No evidence of this was found. 3 or other behaviours of N There is nothing in the literature to indicate that the 3 the species feeding or behavior of Alligator Gar reduces the habitat reduce quality for native species. Alligator Gar feed on rough habitat fishes, but there is no local extirpation of rough fishes quality for noted in native areas and they are considered beneficial native for sportfish populations (biological synopsis). They do species? not forage or burrow N No evidence for eco-engineering activities which would 4 reduce the habitat quality for native species. 4.12 Does the ? No evidence for this was found. 2 species ? There is nothing in literature to specifically indicate a 3 require minimum population size to maintain viable populations minimum population Y Smith et al. (2017: Transactions of the American 2 size to Fisheries Society) report that a modest harvest of 6.5% maintain a a year would result in overharvesting, which is quite viable different than some commercially-harvested species. population? This would seem to suggest that a minimum population size would be required. Smith et al. (2017; Transactions of the American Fisheries Society) suggest: "Alligator Gar populations were highly sensitive to exploitation in our model simulations." 5.01 If the species Y Very large, predatory species (>2 m in total length). May 1 is mainly increase predation pressure on native fish, crustaceans, herbivorous and amphibians/reptiles. or N The species is mainly piscivorous, however, it has been 2 piscivorous/c indicated that it is beneficial to sportfish despite its arnivorous feeding habits (biological synopsis) (e.g., ? Alligator Gar do not have reported impacts in their native 3 amphibia), range, which could be due to the lack of research or that then is its they occur at relatively low density. However, Alligator foraging likely Gar were also deliberately culled, leading to extirpation to have an in some regions. There is some suggestion that this adverse could be due to their impact on sportfish populations. impact in the RA area?

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Table 3-2. Continued

5.02 If the species N Not an omnivore. 3 is an omnivore (or N The species is mainly piscivorous, but also considered 2 generalist an opportunistic feeder noted to have blue crabs and predator), human waste products found in their stomachs then is its (biological synopsis). There is no indication in literature foraging likely that Alligator Gar are adversely impacting the to have an surrounding area adverse N While Alligator Gar will undergo ontogenetic dietary 2 impact in the changes, however this species is not an omnivore RA area? 5.03 If the species N Not in these trophic groups. 4 is mainly planktivorous N The species is not planktivorous, detritivorous, or 4 , detritivorous algivorous or algivorous, then is its N Not considered mainly planktivorous, detritivorous, or 4 foraging likely algivorous. to have an adverse impact in the RA area? 5.04 If the species N Mainly a piscivore, but does consume some 3 is mainly crustaceans. benthivorous, is its foraging N The species is mostly piscivorous and an ambush 4 likely to have predator, waiting for fish to swim right by its head to feed an adverse (biological synopsis) impact in the N Not considered mainly benthivorous, but will consume 4 RA area? benthic organisms such as Blue Crabs. 6.01 Does the N No parental care (Boschung and Mayden 2004). 4 species exhibit parental care and/or is it known to N In the wild and captivity, once eggs are fertilized there is 4 reduce age- no further parental care (biological synopsis) at-maturity in response to N Alligator Gar do not exhibit parental care. 4 environment? 6.02 Does the Y Numerous references. 4 species Y When spawning conditions are met, Alligator Gar 4 produce produce viable gametes in captivity and the wild. There viable are no functionally sterile Alligator Gar noted in literature gametes? Y Not a sterile hybrid. 4

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Table 3-2. Continued

6.03 Is the species N Evidence of confirmed hybridization occurred in captivity 2 likely to between Alligator Gar and Longnose Gar. Herrington, hybridize with S.J., Hettiger, K.N., Heist, E.J. and Keeney, D.B., 2008. native Hybridization between longnose and alligator gars in species (or captivity, with comments on possible gar hybridization in use males of nature. Transactions of the American Fisheries Society native 137:158-164.) A small percentage of Alligator Gar and species to Longnose Gar in Texas were hybrids (Bohn et al. 2017). activate The authors noted that these species spawn in different eggs) in the habitats, making hybridization less likely. Hybridization, RA area? though possible, would most likely be rare. Y There is evidence of hybridization in the wild and 2 captivity of Alligator Gar with Longnose Gar (biological synopsis). There is ongoing research to examine if hybridization has occurred in Florida Y Herrington et al. (2008; Transactions of the American 3 Fisheries Society) indicate: "This conclusive evidence of intergeneric hybridization in the gars may provide insights into phylogenetic relationships in Lepisosteidae and hybridization theory and may explain unsubstantiated reports of gar hybridization in nature and the pet trade." However, without data from the wild, it is not known how likely this will be, especially for Longnose Gar in regions where Alligator Gar are not native, which might lead to a lack of reproductive isolation. 6.04 Is the species N No evidence found. 3 hermaphroditi N There is no evidence in literature of hermaphordites 3 c? N No evidence that the Alligator Gar exhibits routine or 3 even occasional hermaphroditism.

6.05 Is the species N Alligator Gar spawns often in flooded backwaters in 3 dependent on association with aquatic vegetation, submersed the presence terrestrial vegetation, or woody debris (Metee et al. of another 1996). species (or Y No dependence on another species. Alligator Gar are 3 specific dependent on freshwater for successful spawning, habitat mostly on floodplains during flooding periods and over features) to submerged vegetation for the eggs to adhere to complete its (biological synopsis) life cycle? ? No evidence for dependence on other species. 3

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Table 3-2. Continued

6.06 Is the species N Average fecundity is about 4 eggs/g female body weight 4 highly fecund (= 4,000 eggs/kg). Metee et al. 1996. (>10,000 eggs/kg), iteropatric or N Alligator Gar fecundity increases with size, periodic life 2 has an history strategists. They spawn when conditions for extended spawning are met (biological synopsis) and produce up spawning to 4.1 eggs/g (4100eggs/kg) (Ferrera 2001; biological season synopsis) relative to native species? ? Fecundity is thought to be highly variable 3 (https://tpwd.texas.gov/publications/nonpwdpubs/media/ gar_status_073108.pdf), but could be around 4.1 eggs per gram of body weight (Ferrera 2001; Dissertation; Auburn University). Ultimately, this is thought to be a mean estimate and higher estimates could be reasonable.

6.07 What is the 4 Patterson et al. 2018. 4 species’ known minimum 4 4-10, minimum recorded age of sexual maturity and 3 generation spawning is 4 (biological synopsis, Patterson et al.) time (in however, average accepted sexual maturity is 6 (males) years)? and 11 (females) (biological synopsis; Boschung and Mayden 2004)

>10 FishBase (Froese and Pauly 2019) indicate low 2 resilience, late sexual maturation, and average fecundity, to contribute to a high population doubling time. There are few ways to actually determine whether this is actually the case; thus, selected "mostly uncertain".

7.01 Are life N Little chance of unintentional dispersal. 3 stages likely to be N Human movement not likely as eggs are submerged and 3 dispersed adhesive to plant material, young/larval stage do unintentionall resemble sticks but are recognizable for movement and y? not likely to be overlooked

N No evidence for unintentional dispersal. 3

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Table 3-2. Continued

7.02 Are life Y Humans frequently move fish of food or sportfish 4 stages likely importance. to be Y There are places (SE Asia, Texas) that value Alligator 2 dispersed Gar for fishing potential. There were dispersals intentionally intentionally by humans in Hong Kong, releasing by humans Alligator Gar that were bought for (presumably; USGS) (and suitable ornamental purposes in a retention pond in a park habitats (biological synopsis) abundant Y According to USGS NAS (quoted as a personal 2 nearby)? communication with Pam Fuller: ttps://nas.er.usgs.gov/queries/factsheet.aspx?SpeciesID =755), Alligator Gar are popular in the aquarium trade, exhibit large maximum body size (potential tank buster), which would be most likely to be released. However, the question remains, are there suitable habitats outside of the panhandle region of the state. This is not entirely clear; thus, selected mostly uncertain. 7.03 Are life N Unlikely to be a contaminant of other commodities. 3 stages likely N In RA area, there will be no live Alligator Gar sold for 3 to be meat, and only live sale will be for out of state dispersed as ornamental sale a N No evidence for dispersal as a contaminant; while 4 contaminant considered popular in the aquarium trade of (https://nas.er.usgs.gov/queries/factsheet.aspx?SpeciesI commodities D=755), unlikely to accompany other shipments. ? 7.04 Does natural N Alligator Gar eggs are adhesive and stick to vegetation 4 dispersal or sediments. occur as a N Eggs are adhesive and attach to substrate once laid and 4 function of fertilized in low flow flooded area until hatching egg (biological synopsis) dispersal? N Eggs are adhesive, limiting egg dispersal (Mettee et al. 4 1996; Fishes of Alabama and the Mobile Basin).

7.05 Does natural ? No information found. 2 dispersal occur as a function of N There is no direct literature regarding currents and 2 dispersal of Alligator Gar larvae, however, eggs and larvae are laid in larvae (along low flow, shallow, flooded areas (biological synopsis). linear and [or] The likelihood of natural dispersal is low ‘stepping stone’ ? Thought to sink if not actively swimming (Mettee 1996; 3 habitats)? Fishes of Alabama and the Mobile Basin).

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Table 3-2. Continued

7.06 Are juveniles Y Alligator Gar move more during warmer months and 3 or adults of some individuals may travel long distances (Wegener et the species al. 2017) known to Y Adult Alligator Gar move large distances, potentially due 4 migrate to resource partitioning (Weneger 2017;2018; Biological (spawning, Synopsis). In Florida, there is seasonal variation in smolting, movement, with most happening in the warmer months. feeding)? The linear home range for Alligator Gar in Florida was 41.32 km, in Alabama the greatest recorded movement for Alligator Gar is 10.2 km (Boschung and Mayden 2004; biological synopsis) Y Highly mobile species depending upon habitat: 1) 0.89 to 4 101.58 km in Pensacola Bay (Wegener et al. 2017); 2) home ranges to 60 km, with some to 100 km (Buckmeier et al. 2013); 3) home range from 6.57 to 16.7 km (Sakaris et al. 2003; Brinkman 2003). 7.07 Are eggs of N No evidence found 2 the species known to be N There is no evidence of this in literature 3 dispersed by other animals N No evidence for dispersal by other animals externally. 4 (externally)?

7.08 Is dispersal ? No information found. 1 of the ? There is nothing in literature to indicate that dispersal is 1 species species density dependent. During the winter and density spawning Alligator Gar form larger aggregations, in the dependent? warmer months they are farther dispersed (Wegener 2017; 2018; biological synopsis) ? No evidence for density dependent dispersal, which 3 could be due to difficulty in assessing the population status of Alligator Gar, or that they naturally occur at lower density than most fish species. 8.01 Are any life Y Larger juveniles and adults can survive periods out of 4 stages likely water (air breather). to survive out of water Y No literature that specifically references ability to survive 3 transport? outside of water, adults have been noted to survive periods of time out of water (air breathers)

? No specific evidence for ability to survive out of water 3 transport. However, there are anecdotal accounts of extended periods out of the water.

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Table 3-2. Continued

8.02 Does the Y Air-breathing allows Alligator Gar to use hypoxic waters 4 species (Schultz 2004; Omar-Ali et al. 2016). The species also tolerate a tolerates a wide temperature range (Biological wide range of Synopsis). water quality Y Alligator Gar are found in a range of water quality 4 conditions, conditions and are noted to survive low DO (air especially breathers), temperatures from 1-30C (biological oxygen synopsis) depletion and Y The native distribution of Alligator Gar extends to Illinois, 3 temperature with temperatures below 5C; at the southern portions of extremes? the range temperature can exceed 30C. Can tolerate a range of DO because of a modified swim bladder. 8.03 Is the species Y Gar are frequently collected using rotenone, often at 2 readily lower doses than allowed by the label (e.g., 3 vs 5 ppm). susceptible to However, gar are more resistant than many fishes piscicides at (Hubbs 1963). Hubbs, C., 1963. An evaluation of the use the doses of rotenone as a means of" improving" sports fishing in legally the Concho River, Texas. Copeia, 1963(1), pp.199-203. permitted for Some gar may survive rotenone treatments. use in the Y Little literature on the topic; gar are collected with 2 risk rotenone at levels lower than recommeneded on label. assessment Gars are more resistant than other species as they are area? air breathers (Hubbs 1963). EDIS recommends 2 ppm and 5% rotenone applied at 1.5 ppm did not effect Alligator Gar (Harris et al. 1973) but did affect other gar species. Y Higginbotham and Steinbach (Renovation of Farm 3 Ponds; TAMU extension) indicate gar (not specific to Alligator Gar) can be difficult to kill with rotenone. Hoyer and Canfield (1994; Handbook of Common Freshwater Fish in Florida Lakes) routinely sampled gar with rotenone and blocknets. Thus, Alligator Gar may exhibit at least a baseline susceptibility to rotenone. Lower certainty was selected. 8.04 Does the Y Flooding benefits reproduction and potentially 3 species recruitment of Alligator Gar through increased access to tolerate or spawning habitat and juvenile/nursery habitat. benefit from N Environmental disturbances are not tolerated by Alligator 3 environmenta Gar, the specific needs for spawning are impaired by l environmental disturbance and reduce successful disturbance? spawning (e.g. building of dams restricting floodplains) N No evidence that the Alligator Gar benefits from 3 disturbance; in fact, it may be just the opposite. Dam construction has altered habitat availability, which is thought to have contributed to a decline of the Alligator Gar in part of its range (Mettee et al. 1996. Fishes of Alabama and the Mobile Basin).

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Table 3-2. Continued

8.05 Are there N Although some predators would consume larval and 3 effective juvenile Alligator Gar, adults would be resistant to most natural predators except for Alligators, Otters, and Humans. enemies of N Alligator Gar have few natural enemies, but the RA area 3 the species has both alligators and humans in close vicinity. Alligator present in the Gar outgrow alligator quickly and the human impact is risk low assessment area? Y At least for larval, juvenile, and subadult Alligator Gar, 3 effective predators would be other gar species, catfish, bass. However, when they reach a certain size, only alligators and humans would be effective predators.

Figure 3-17. Distributions of FISK risk category scores with the average and standard deviation.

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Table 3-3. Breakout groups and overall risk assessment results. Opinions different within groups where there are multiple risk ratings or certainty values. The composition of breakout groups differed for the two sections (establishment and consequences). Risk levels are H = High, M = Medium, and L = Low. The overall risk of establishment is the lower of the four ratings and the overall risk of consequences is the highest rating between environmental and economic (unless both are low, then social/political). The ORP is the average of establishment and consequences, rounded up. Certainty levels are as follows: VU = very uncertain, RU = reasonably uncertain, MC = moderately certain, RC = reasonably certain, and VC = very certain.

Risk Type Category Group 1 Group 2 Overall Group Risk Certainty Risk Certainty Risk Certainty Level Level Level Probability of Presence in H RC H VU H RC Establishment Pathway H VC H VC Introduction H MC H RC H MC H MC H RC Colonization M VU M RU L-M VU L-M VU L-M RU M RU L RU Spread L RU M MC L MC L MU M MC H RC H MC Overall M L-M L-M Consequences Environmental M VU L RC L-M RU of L MC M RU Establishment M RU Economic M RU L RC M MC M MC L MC L MC M MC Social/political L VU L-M RC L-M RU M MC Overall M M M Overall Risk M M M Potential (ORP)

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Table 3-4. Results of the evaluation of the stakeholder risk assessment workshop. All participation was anonymous, with seven attendees providing answers following the completion of the workshop.

Please rate how well this meeting did each of the following: (Not at (Very Well)

all) 1 2 3 4 Informed about the objective of the   29% 71% meeting/panel Informed about risk assessment and   43% 57% management

Gathered participants of varying    100% expertise for the stakeholder panel

Gathered input from participants    100% Accurately captured the output (Generic Analysis and risk   14% 86% management) of the panel Please state your level of agreement with the following statements: Strongly Strongly Disagree Agree Disagree Agree

I was able to communicate my ideas    100%

Others heard my ideas    100%

I heard the ideas of others    100% To what extent did you find the stakeholder panel useful? (Not at 1 2 3 4 5 (Very) all) - - - 57% 43% How would you rate the meeting overall? (Poor) 1 2 3 4 5 (Excellent) - - - 43% 57% Would you attend future meetings of this type? No Maybe Yes - - 100%

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CHAPTER 4 DISCUSSION

Increasingly, natural resource managers are concerned with the impacts of introductions of non-native species on native species and ecosystems (Elvira and

Almodóvar 2001; Gozlan et al. 2010; Cucherousset and Olden 2011). Overall Alligator

Gar risk to Florida, in the native and non-native range, was determined to be medium.

The risk screen estimated a low-medium risk level for Alligator Gar, an outcome largely in agreement with the comprehensive assessment completed by a stakeholder panel.

Factors increasing the invasion potential of Alligator Gar were salinity tolerance, high migration potential, and data gaps in Alligator Gar biology. Factors that decreased the risk potential of Alligator Gar aquaculture in Florida were the lack of invasion history and lack of documented impacts in and outside of the native range. Ultimately, the risk assessment concluded that if cultured responsibly, this native fish in aquaculture presents a low-medium invasion potential.

The FISK and Generic Analysis results were similar to a U.S. federal risk screen of Alligator Gar (USFWS 2017). The U.S. Fish and Wildlife Service completed an

Ecological Risk Screening Summary (ERSS) screening of Alligator Gar for the entire

United States and found that the perceived risk of Alligator Gar outside of their native range is uncertain, their equivalent to medium risk, indicating additional assessment was needed (U.S.F.W.S. 2017). The FISK results did not necessarily mean that additional assessment was required, conservative risk tolerance led to the additional assessment of a Generic Analysis. On further assessment, the medium risk rating was confirmed.

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The risk assessment of Alligator Gar suggested lower risk than that determined by previous risk assessments of large-bodied, predatory fishes in Florida. Arapaima risk for the state was medium overall, with a minimal high score in subtropical and tropical south Florida (Hill and Lawson 2015). Management agencies determined that current conditional species regulations provided adequate risk mitigation to allow culture (Hill and Lawson 2015). The Barramundi Perch assessment resulted in a high risk rating, yet the agencies concluded that increased more stringent conditional provisions were acceptable risk mitigation to allow commercial culture (Hardin and Hill 2012). The main change mandated indoor, tank culture only.

Additionally, many ornamental species that are currently in the aquarium trade in

Florida have higher FISK risk scores than Alligator Gar. The Neon Tetra Paracheirodon innesi, Guppy Poecilia reticulata, and Betta Betta splendens all have FISK scores of 5 for Florida (Lawson et al. 2015; Figure 4-1). These small ornamental species have comparable low-medium risk scores to Alligator Gar.

High numbers of historic introductions of freshwater fishes, both successful and failed, provide insights into the types of fishes most likely to prove invasive. Life history traits characteristic of species with success potential in Florida include parental care, air breathing, no fluvial dependence, moderate or large body size, and large eggs (Lawson

2018). Successful species trend towards the equilibrium strategy within the Winemiller and Rose (1992) triangular life history model (Lawson 2018). Non-native species with no parental care have a history of failing to establish in Florida, with one exception

(Oriental Weather Loach Misgurnus anguillicaudatus; Lawson 2018). Alligator Gar is a periodic life history strategist (Winemiller and Rose 1992) with late sexual maturity and

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a partially fluvial-dependent reproductive strategy, both traits are not associated with success in establishing outside of their native range in Florida (Lawson 2018).

Florida has seemingly suitable habitat in the coastal river systems along the northern Gulf of Mexico coast, including the Suwannee River in Florida’s Big Bend.

While the Alligator Gar have an extended spawning period across its native range

(January to September; Echelle and Riggs 1972), flood periods in the peninsula may not coincide with spawning habits.

Specific questions related to potential establishment in Florida include the lack of observed population increases within the native Florida range despite more than a decade of harvest closure and protection as well as failure to move beyond the western panhandle. There is no explanation in literature for why Alligator Gar have not moved into peninsular Florida. The lack of movement suggests a strong barrier to spread and establishment is present, that the low-density populations of Alligator Gar in Florida may represent a peripheral population that exists at the edge of their native range, and it has been proposed that eastern populations of Alligator Gar are more marginal and have less reproductive output.

The Longnose Gar Lepisosteus osseus displays similar distribution to Alligator

Gar in the southeast United States; found in Gulf Slope drainages from central Florida to Rio Grande drainage in Texas and Mexico as well as the panhandle (Froese and

Pauly 2019). Dispersal does not appear to be the barrier, as long-range movement

(linear home ranges up to 101 km in Florida; Wegener et al. 2017) has been recorded across the native range, the wide salinity tolerance of adults, and the propensity to use bays, estuaries, and marine habitats for habitat and dispersal. The species native range

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extends further south latudinally through Mexico, to the Rio Papaloapan Basin in

Veracruz, Mexico (Figure 4-2; Miller 2005). The CLIMATCH map (Figure 3-11) indicates that a large proportion of the number of match cells at this data point in Veracruz,

Mexico contributed to the target region match score and contribution to the CLIMATCH locations. Seasonal variation in ovarian weight indicated peak spawning in July and

August in northeastern Mexico (Garcia de Leon et al. 2001) while April to June is generally accepted as the spawning season for Alligator Gar throughout their native range (Suttkus 1963; Garcia de Leon et al. 2001; Miller 2005). Oklahoma, Texas, and

Alabama report a broader spawning period, January to September. Spawning throughout the native range of Alligator Gar is reported with flooding (Suttkus 1963;

Garcia de Leon et al. 2001; Miller 2005), with the highest rainfall in Mexico reported in

June to September, consistent with the peak spawning period indicated by Garcia de

Leon et al. (2001; https://weather-and-climate.com/veracruz-July-averages). Peninsular

Florida and the native range of Alligator Gar in Mexico are very similar in latitude, rainfall, and temperature (CLIMATCH). A high climate match does not mean the habitat is suitable for an organism, as evidenced by the potential barriers preventing successful spawning and recruitment.

General comments on the benefits of Alligator Gar aquaculture are positive if risk mitigation (FDACS) is updated to reflect and manage the potential genetic implications

(e.g. Longnose Gar and Florida Gar) in the peninsula. Risk of escape was considered low at the production level due to risk mitigation factors, including BMPs and potential increased regulations for production, permitting, and transfer. There are further scientific benefits of understanding Alligator Gar biology and reproduction, as well as potential for

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Alligator Gar stock enhancement in Florida. Allowing commercial culture of Alligator Gar also presents a chance to reduce illegal trade and introductions of unknown diseases as a result of import for sale.

Data Gaps and Research Recommendations

Several data gaps, identified throughout the risk assessment process, exist for

Alligator Gar. Some of the listed data gaps are currently under research by FWC. Data gaps provide guidelines for research recommendations and identification of potential hazards to inform management decisions. Additional research and assessment would decrease uncertainty of risk perception and inform the risk potential for Florida.

Research recommendations (some are currently undertaken or planned with

FWC) that would fill or partially fill data gaps include: effects of hybridization of Alligator

Gar with other species, population dynamics and spread potential, investigation of

“brackish water” populations, reproduction requirements, potential genetic impacts on native Alligator Gar from commercial aquaculture, potential to use commercial aquaculture as a source for Alligator Gar stock enhancement, predator-prey dynamics, and population dynamics and spread modeling studies. Recent and ongoing studies by agencies throughout the native range of Alligator Gar would provide data sources and procedures to support similar evaluations and projects in Florida.

Management Implications and Risk Mitigation

Allowing commercial culture of Alligator Gar in Florida would be consistent with the outcome of the risk assessment effort. Also, culture of Alligator Gar would already be legal if not for the fishing and possession ban imposed on Alligator Gar in Florida due to uncertainty concerning abundance and dynamics in Florida.

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The predicted risk assessment was based on no live sales in Florida, other than to those who hold necessary permits. If live sales are considered, the question of if there would be an increase in risk would need to be further assessed. Discussion on this topic determined that as it is present already, it would likely be a marginal increase.

Aquaculture of a medium risk species in Florida is common and consistent with aquaculture BMPs in general (FDACS 2019), and for some medium risk species with specific concerns, the conditional species provisions. A number of species that are classified high risk are cultured under conditional species provisions (e.g. Barramundi

Perch, Hardin and Hill 2012; Arapaima, Hill and Lawson 2015). Conditional species provisions include strict containment, sales, and record keeping practices, and, in some cases, indoor culture. If restricted species are permitted to be cultured outdoors, the lowest point of the top edge of the pond berm must be one foot above the 100-year flood elevation issued by FEMA (FDACS 2019).

Florida aquaculture BMPs provide risk mitigation concerning escape from aquaculture facilities of all cultured species (Tuckett et al. 2016; 2016b). Mitigation efforts would need to be primarily focused on biosecurity, record keeping, and limits as to who can possess Alligator Gar in Florida. If additional risk mitigation was deemed necessary, extra conditions would be placed on Alligator Gar aquaculture. Conditional species level containment would include no live sales in the state to anyone without the appropriate permits; this would preclude sales of live food fish, ornamentals, or pond stockers. Additional site restrictions can also be imposed to prevent culture in the watershed of the native range of Alligator Gar. Should additional research and assessment be completed, the recommendations would be adjusted accordingly.

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Understanding the risk potential of Alligator Gar in Florida is important to support management decisions, for management or policy recommendations and risk mitigation methods. The risk assessment process identifies the level of acceptable risk and concerns of stakeholders, which are used to determine risk mitigation methods and support future management decisions based on a spectrum of risk tolerance.

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Figure 4-1. FISK scores of five ornamental or food fish species compared to Alligator Gar. The orange line represents the calibrated 10.25 invasive/non-invasive threshold for Florida.

Figure 4-2. Distribution of Alligator Gar in Mexico (Miller 2005).

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APPENDIX A STAKEHOLDER GENERIC ANALYSIS WORKSHEET

Group Number_____

Probability of Establishment Rating: L = Low, M = Medium, H = High Certainty: VU = Very Uncertain; RU = Reasonably Uncertain; MC = Moderately Uncertain; RC = Reasonably Certain; VC = Very Certain 1. Nonindigenous Aquatic Organisms 2. Entry Potential - Estimate the Associated with Pathway (at Origin) - probability of the organism Estimate the probability of the surviving in transit (characteristics organism being on, with, or in the of this element include hitchhiking pathway (e.g. does the organism ability in commerce or whether it is show a convincing temporal and deliberately introduced (e.g. spatial association with the pathway?). biocontrol agent or fish stocking)).

Rating: L M H Rating: L M H

Certainty: VU RU MC RC VC Certainty: VU RU MC RC VC

Justification: Justification:

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3. Colonization Potential - Estimate 4. Spread Potential - Estimate the the probability colonizing and probability of the organism maintaining a population spreading beyond the colonized (characteristics include the organism areas (characteristics of this coming in contact with adequate food element include ability for natural resource, encountering appreciable dispersal, ability to use human abiotic and biotic environmental activity for dispersal, and the resistance, and the ability to estimated range of probable reproduce in the new environment). spread).

Rating: L M H Rating: L M H

Certainty: VU RU MC RC VC Certainty: VU RU MC RC VC

Justification: Justification:

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Group Number_____

Consequences/Impacts of Establishment Rating: L = Low, M = Medium, H = High Certainty: VU = Very Uncertain; RU = Reasonably Uncertain; MC = Moderately Uncertain; RC = Reasonably Certain; VC = Very Certain 2. Environmental Impact Potential - 1. Economic Impact Potential - Estimate economic impact if Estimate environmental impact if established (e.g. economic established (e.g. ecosystem importance of host or control costs). destabilization).

Rating: L M H Rating: L M H

Certainty: VU RU MC RC VC Certainty: VU RU MC RC VC

Justification: Justification:

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3. Perceived Impact (Social and Political Influences) - Estimate impact from social and/or political influences (e.g. aesthetic damage).

Rating: L M H

Certainty: VU RU MC RC VC

Justification:

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APPENDIX B WORKSHOP EVALUATION FORM

Please read this document carefully before participation in this study.

The purpose of these evaluations is to assess the success of the meeting. There is no compensation for participation but know that your participation is important. The survey is anonymous; be assured that in our analysis and reporting of results your answers will not be connected with you. There are no risks to you from participating in this study. Your participation in this study is completely voluntary, you have the right not to answer any specific questions and you may withdraw your consent at any time. There is no penalty for not participating.

If you have any questions concerning this study, please contact: Lauren Lapham, Graduate Student Tropical Aquaculture Laboratory University of Florida Ruskin, FL 33570 Phone: (813) 671-5230 E-mail: [email protected]

Whom to contact about your rights as a research participant in the study: UFIRB Office Box 11225 University of Florida, Gainesville, FL 32611-2250 Phone: (352) 392-0433

Please rate how well this meeting did each of the following:

(Not at (Very

all) 1 2 3 Well) 4 Informed about the objective of     the meeting/panel Informed about risk assessment     and management Gathered participants of varying expertise for the stakeholder     panel

Gathered input from participants     Accurately captured the output     (Generic Analysis and risk

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management) of the panel

Please state your level of agreement with the following statements:

Strongly Strongly Disagree Agree Disagree Agree

I was able to communicate my     ideas

Others heard my ideas    

I heard the ideas of others    

To what extent did you find the stakeholder panel useful?

(Not at all) 1 2 3 4 5 (Very)

How would you rate the meeting overall?

(Poor) 1 2 3 4 5 (Excellent)

Would you attend future meetings of this type?

No Maybe Yes

How would you improve this meeting or panel?

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BIOGRAPHICAL SKETCH

Lauren was born in Houston, Texas, where her family lived until moving to

Florida when she was young. Lauren has spent most of her life in Florida, growing up swimming and riding horses. Her interest in fisheries and aquatic sciences grew with her time on the water and outdoors.

While pursuing a Bachelor of Science in natural resource conservation at the

University of Florida, she had the opportunity to work as a science diver in Silver

Springs, assisting with collection and analysis of aquatic vegetation and increasing her interest in the aquatic environment. In summer 2016, she had the opportunity to intern for Sea Grant, acting as coordinator for education and outreach efforts related to conservation and aquatic science. After graduating in 2016, Lauren began a graduate certificate program in aquaculture and fish health with the University of Florida. She completed her graduate certificate while working as a science diver, participating in coral restoration, fisheries, and marine research in the Cayman Islands.

The opportunity to attend the University of Florida for a Master of Science in fisheries and aquatic sciences arose in the Spring of 2018. Lauren began working as a research assistant at the UF/IFAS Tropical Aquaculture Laboratory in Summer 2018, participating in risk assessments for non-native species in Florida and assisting with non-native species and fisheries research.

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