2020 Virtual Annual Meeting of the American Elasmobranch Society

Day 1 (November 7th, 12-2:20pm EST)

Spatial Ecology • Behavior ​ ​

Day 2 (November 14th, 12-2:20pm EST)

Policy and Human Dimensions of Shark Fishing • Effects of Shark Fishing and Trade • At-Risk ​ ​ ​ ​ Species and Habitats

Day 3 (November 21st, 12-2:40pm EST)

Reproduction and Physiology • Diet, Pollutants, and Health • Genetics and Evolution ​ ​ ​ ​

Presentation recordings will be available after the conference at elasmo.org ​

Thank you to all members of the AES community presenting at and attending this meeting for making it a success!

A special thanks to the AES Outreach and Education Committee for volunteering their time to organize this meeting (Chuck Bangley, Rachel Skubel, Jennifer Wyffels, Joshua Moyer, and David Ebert)

2020 Virtual Annual Meeting of the American Elasmobranch Society - Schedule

1. Schedule of Presentations Presentations are 8 minutes long, followed by 2 minutes for questions, except for lighting talks (⚡) which are 5 minutes long followed by 2 minutes for questions. Please arrive at the Zoom session 5-10 minutes ahead of each session, as the first talk will begin promptly at its assigned time.

Day 1 (November 7th, 12-2:20pm EST)

Session 1: Spatial Ecology

Time (EST) Presentation Title Authors 12:00 #1 The Effect of Tidal and Diel Cycles on Movement and *Dawdy A, Peterson C, Keller ​ ​ Spatial Use Patterns of Bull Sharks (Carcharhinus leucas) and B, Grubbs D ​ ​ Bonnetheads (Sphyrna tiburo) in Apalachicola Bay, FL ​ ​ 12:10 #2 Seasonal environmental drivers of migratory movements *Bowers B, Kajiura S ​ in the blacktip shark, Carcharhinus limbatus ​ 12:20 #3 Residency, Diel Movement, and Tidal Patterns of *Arnt JL, Abel D ​ ​ Bull Sharks (Carcharhinus leucas) in Winyah Bay, SC ​ ​ 12:30 #4 Movement and habitat use of sand tiger sharks *Marens M, Fox D, Wetherbee ​ ​ (Carcharias taurus) in North Carolina coastal waters B, Southwood-Williard A, ​ ​ Scharf F 12:40 #5 Study of nearshore great white shark behavior off the *Sexton K, Kolyvek K, Holt R, ​ ​ coast of Cape Cod using drone based tracking methods with Reulan Jd implications for public safety. 12:50 #6 Spatial distribution and connectivity of lemon sharks *Kessel ST, Kohler NE, Casey ​ ​ (Negaprion brevirostris) in the northwest Atlantic JG, Brooks JL, Feldheim KA, ​ ​ Rutzen H, Sawyna J, Frazier B, Gruber SH 1:00 ⚡ #7 Testing Errors of Light Geolocations from Pop-Up *Farrugia TJ, Lowe CG, ​ ​ ​ Satellite Archival Transmitting Tags Deployed on a Coastal O'Sullivan J Marine Species

Break until 1:20 pm

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Session 2: Behavior

Time (EST) Presentation Title Authors 1:20 #8 Scalloped hammerhead sharks swim on their side with *Royer M, Maloney K, Meyer ​ ​ diel shifts in rolling behavior and swimming performance C, Cardona E, Payne N, Whittingham K, Silva G, Blandino C, Holland K 1:30 #9 Combining Movement Behavior and Environmental *Bangley C, Ogburn MB ​ Data to Delineate Potential Essential Habitat for Migratory Elasmobranchs 1:40 #10 Map-like use of earth’s magnetic field in sharks *Keller B, Putman NF, Grubbs ​ ​ RD, Murphy T 1:50 #11 Foraging aspects of Cookiecutter Shark (Isistius spp.) in *dos Santos BT, Veloso J, ​ ​ ​ ​ an equatorial Mid-Atlantic archipelago Macena B, Hazin F 2:00 #12 Reverse diel vertical movements of oceanic manta rays *Andrzejaczek S, Schallert R, ​ ​ off the northern coast of Peru and implications for Forsberg K, Arnoldi N, conservation Cabanillas M, Purizaca W, Block B 2:10 #13 Collective swimming kinematics of Carcharhinus limbatus *Ruddy BT, Kirwan DJ, ​ ​ to Sphyrna mokarran during wild predation events Kajiura SM, Porter ME ​ ​

Day 2 (November 14th, 12-2:20pm EST)

Session 1: Policy and Human Dimensions of Shark Fishing ​

Time (EST) Presentation Title Authors #14 Recreational shark fishing in Florida: how early career *Shiffman DS ​ 12:00 research and strategic science communication changed the law to protect threatened species 12:10 #15 Balancing conflicting needs in the sustainable *Brewster-Geisz K, Curtis T, ​ ​ ​ management of U.S. Atlantic shark fisheries DuBeck G 12:20 #16 When fishing bites: Quantifying angler response to shark *Casselberry GA, Markowitz ​ ​ ​ depredation EM, Skomal GB, Danylchuk AJ 12:30 #17 The who, what, where, and how-many of shore-based *Brooks JL, Guay J, Nguyen ​ ​ ​ shark fishing in Florida, USA. VM, Chapman J, Tabatabai D, Cooke SJ, Medd H

Break 12:40-12:45

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Session 2: Effects of shark fishing and trade

Time (EST) Presentation Title Authors 12:45 #18 Three-Dimensional Movements and Bycatch *Curtis T, Shaw R, Galuardi ​ ​ ​ Susceptibility of Young-of-the-Year White Sharks in a B, Metzger G, Fischer C, Summer Nursery Area McCallister M, Ajemian M 12:55 #19 Tracking the fin trade: genetic identification of supply *Cardeñosa D, Fields A, Shea ​ ​ ​ chain starting points for three CITES-listed shark species S, Feldheim K, Chapman D 1:05 #20 Measurement of 1α-hydroxycorticosterone (1αOHB): *Wheaton CJ, Burns CM, ​ ​ ​ Correlations with Secondary Stress Markers in Smukall MJ, Hendon J, Aquarium-Managed, Semi-Wild and Wild Populations of Rays Mylniczenko ND and Carcharhinid Sharks 1:15 #21 Plasma 1α-hydroxycorticosterone measurements in Tiger *Newton AL, Mylniczenko ​ ​ ​ (Galeocerdo cuvier) and White (Carcharodon carcharias) sharks ND, Hyatt MW, Curtis TH, ​ ​ ​ ​ during scientific sampling, tagging, and release Metzger G, Fischer C, Wheaton CJ 1:25 #22 The open access hammerhead shark fishery in Trinidad, *Kingon KC, Ramdoo T, ​ ​ ​ food for thought Steele AM, Wilson A, Barker AM, Portnoy DS, Grubbs RD, Douglas E

Break 1:35 - 1:40

Session 3: At-risk species and habitats

Time (EST) Presentation Title Authors 1:40 #23 Reducing captures of evolutionarily distinct and globally *Ichsan M, Ula S, Booth H, ​ endangered (EDGE) thresher sharks in Western Indonesia Dharmadi H 1:50 #24 Urban Manta Rays: Potential Manta Ray Nursery Habitat *Pate J, Marshall A ​ ​ along a Highly Developed Florida Coastline 2:00 #25 Home sweet home: site fidelity of the reef manta ray to a *Knochel A, Cochran J, ​ ​ remote coastal bay in the Sudanese Red Sea Braun C, Klaus R, Chekchak T, Hill G, Alhasan N, Younnis M, Kessel S, Hussey N, Berumen M 2:10 ⚡ #26 Conservation priority shark species display higher *Albano P, Fallows C, ​ ​ ​ abundances within a marine reserve in a global biodiversity Fallows M, Schuitema O, and fishing hotspot Bernard A, Sedgwick O, Hammerschlag N

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Day 3 (November 21st, 12-2:40pm EST)

Session 1: Reproduction and physiology ​

Time (EST) Presentation Title Authors 12:00 #27 Hannibal Shark Embryos: A case of extreme maternal *Amorim-Lopes C, Araujo ​ ​ ​ investment and survival cannibalism? NLF, Hauser-Davis RA, Neves LS 12:10 #28 Influence of female size in the variation of Multiple *Rendón-Herrera J, ​ ​ ​ Paternity in the brown smooth-hound shark Mustelus henlei. Saavedra-Sotelo NC. ​ ​ 12:20 #29 An inconvenient tooth: evaluating female choice in *Lyons K, Kacev D, Mull ​ ​ ​ multiple paternity in sharks, skates and rays CG 12:30 ⚡ #30 Multiple reproductive adaptations ameliorate pup *Deeken D, Gainsbury A, ​ ​ ​ ​ mortality by predation in Elasmobranchii shark Cassill DL 12:37 ⚡ #31 Multimodal imaging and analysis provide new insights *Camilieri-Asch V, Yopak ​ ​ ​ ​ into the organisation of olfactory inputs in a shark model KE, Shaw JA, Partridge JC, species (Chiloscyllium punctatum) Collin SP ​ ​

Break Until 12:50

Session 2: Diet, pollutants, and health

Time (EST) Presentation Title Authors 12:50 #32 Interspecific variability in the trophic ecology of two *Marsaly B, Matich P ​ ​ ​ co-habiting apex predators in coastal Texas. 1:00 #33 Lipid metabolites as energy stores in stingrays *Moniz LE, Lyons KD, ​ ​ ​ Hoopes L, Lewis JM, Bedore CN 1:10 #34 Acute Phase Reactants in the Nurse Shark, Ginglymostoma *Rusnak E, Hammerschlag ​ ​ ​ ​ cirratum N, Merly M 1:20 ⚡ #35 Evaluation of the heavy metal content of the Bull Shark *Fola-Matthews O, ​ ​ ​ ​ Carcharhinus leucas off the Coast of Nigeria. Soyinka O ​ 1:27 ⚡ #36 The ChondroCensus: A New Tool for Global *Janssen J ​ ​ Collaboration and Communication

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Session 3: Genetics and evolution

Time (EST) Presentation Title Authors 1:40 #37 Genetic population dynamics of scalloped hammerhead *Harned S, Bernard A, ​ ​ ​ sharks in the Galápagos Islands Mehlrose M, Salinas P, Feldheim K, Shivji M 1:50 #38 The role of the American continent on the diversification *Petean FF, Yang L, ​ ​ ​ of the stingrays’ genus Hypanus Rafinesque, 1818 Corrigan S, Lima SMQ, (Myliobatiformes: Dasyatidae) Naylor GJP 2:00 #39 Dorsal fin mystery: Insight for shark bauplan *Angibaud M, Berio F, ​ ​ ​ Cloutier R, Naylor G 2:10 #40 The Skatey Bunch: Population Structure of the Clearnose *Nelson LN, McDowell ​ ​ ​ Skate (Rostroraja eglanteria) in the Western North Atlantic Using JR ​ ​ SNP Genetic Markers 2:20 #41 Is blood thicker than water? Relatedness and kinship in *Morgan T, Barry S, ​ ​ ​ juvenile bull sharks (Carcharhinus leucas) Gulak SJB,. Drymon JM, ​ ​ Seubert EA, Daly-Engel TS 2:30 ⚡ #42 Cryptic Speciation and Genetic Diversity in Dogfish Sharks *McCall C, Daly-Engel T ​ ​ ​ ​ (Genus Squalus)

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All presentations will be available as a recording for AES Members unless otherwise indicated.

Day 1 (November 7th, 2020)

Session 1: Spatial Ecology

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The Effect of Tidal and Diel Cycles on Movement and Spatial Use Patterns of Bull Sharks (Carcharhinus leucas) and Bonnetheads (Sphyrna tiburo) in Apalachicola Bay, FL

*Dawdy A, Peterson C, Keller B, Grubbs D ​ ​

Florida State University Coastal & Marine Laboratory [email protected]

Apalachicola Bay is a large, highly productive estuary in the northeast Gulf of Mexico. It is home to a federally designated National Estuarine Research Reserve and lies in a biodiversity hotspot that supports many economically and ecologically important species of fishes and invertebrates. Bull sharks (Carcharhinus leucas) are among the top predators in the system and have a broad salinity tolerance ranging from freshwater to full seawater. Bonnetheads are intermediate predators that primarily forage on small crustaceans such as juvenile blue crabs (Callinectes sapidus). Both species are subject to intense fishing pressure through directed harvest and bycatch in recreational and commercial fisheries. In this study, over two summers, four bull sharks and six bonnetheads (Sphyrna tiburo) were tracked consecutively using active and passive acoustic telemetry in order to compare spatial use and movement patterns across tidal and diel cycles for each species. In bonnetheads, mature individuals used a larger spatial area at night and left the bay multiple times, potentially to forage. Swimming speed was significantly influenced by tidal and diel cycle. This information will be useful in future management efforts for these species and may be important in understanding the effects of water management in the Apalachicola River watershed – a significant socio political issue in this region. Additionally, consecutive passive and active data from the same individuals suggests that swimming speed influences passive detection efficiency.

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Seasonal environmental drivers of migratory movements in the blacktip shark, Carcharhinus limbatus

*Bowers B, Kajiura S ​ ​

Florida Atlantic University [email protected]

Migration is often driven by unfavorable environmental conditions. Blacktip sharks, Carcharhinus limbatus, in the western Atlantic Ocean migrate from overwintering grounds in southeastern Florida to mating grounds in Georgia and the Carolinas. Seventy years ago, only vagrants were reported north of Cape Hatteras, NC. Since that time, sea surface temperatures have increased 0.85°C and the migratory pattern has changed with the northern boundary now off the coast of Long Island, NY. We instrumented 52 blacktip sharks with acoustic transmitters to determine the seasonal environmental drivers of the migratory pattern. We used detections from collaborative acoustic telemetry networks to track the animals along their route. However, the resultant detection data were often sporadic due to the non-uniform spatial orientation of receivers within the arrays. To regularize the temporal component of these data, we employed a correlated random walk model. We then weighted and paired environmental variables to observed and predicted marine locations and used a generalized least squares model to determine what environmental factors drive the latitudinal movement of blacktip sharks during each season. During spring, salinity, photoperiod, and maximum latitude were positively correlated, and chlorophyll was negatively correlated with northward movements, while in the summer, salinity, maximum latitude, and total length of the animal positively correlated with northward movements. Sea surface temperature and photoperiod were directly correlated, and chlorophyll and maximum latitude were inversely correlated with southward movements in the winter while no measured drivers reliably predicted movement in the fall.

[This presentation will not be available as a recording]

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Residency, Diel Movement, and Tidal Patterns of Bull Sharks (Carcharhinus leucas) in Winyah Bay, SC

*Arnt JL, Abel D ​ ​

Coastal Carolina University [email protected]

Understanding the spatial-temporal habitat use of apex predators throughout their ontogeny is critical to stock assessors and fisheries managers. Bull sharks (Carcharhinus leucas) reside in estuarine nursery habitats all year as small juveniles for foraging and predator avoidance benefits. However, similar residency data on large (> 185 cm) juvenile bull sharks is sparse and incomplete in the western Atlantic Ocean. Winyah Bay, SC, is a partially mixed estuary and serves as seasonal habitat for eleven shark species including large juvenile bull sharks. My study implanted seven large juvenile bull sharks in Winyah Bay, SC, with acoustic transmitters to determine their residency, diel, and tidal patterns. From July to October 2019 we detected 10,805 signals from eight receivers and coupled data with abiotic sampling stations. Individuals from this study showed high residency values during July – September with a significant decline in October and were present in warm, normoxic, brackish water. Bull sharks were detected in specific regions of Winyah Bay based on diel period rather than tidal influences. Additionally, Hurricane Dorian made landfall in SC during our study and bull sharks left Winyah Bay for several days and were detected in adjacent estuary environments. Winyah Bay serves as habitat for large juvenile bull sharks, although its importance is not yet known.

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Movement and habitat use of sand tiger sharks (Carcharias taurus) in North Carolina coastal waters

*Marens M (1), Fox D (2), Wetherbee B (3), Southwood-Williard A (1), Scharf F (1) ​ ​

(1) University of North Carolina-Wilmington, (2) Delaware State University, (3) University of Rhode Island [email protected]

In the western north Atlantic, sand tiger sharks (Carcharias taurus) range from the Gulf of Maine-Gulf Mexico and are listed as a species of concern due to their coastal aggregating behavior and slow life-history strategy. The reproductive cycle of C. taurus includes seasonal migrations extending hundreds of kilometers. Coastal waters off North Carolina serve as a migratory corridor, but the degree of residency in these waters is unknown. Aggregations of C. taurus have been observed near previously hypothesized birthing areas along southern US Atlantic waters and are presumed to be associated with seasonal reproduction. However, patterns of seasonal residency, habitat use, and migration at finer spatial scales are lacking. It is hypothesized that pregnant females may utilize habitats differently than resting females and that residency of mature female sand tigers exist in North Carolina coastal waters. Using passive acoustic telemetry techniques, movements of mature female sand tiger sharks were tracked (n=32) from 2016-2019. On-board ultrasound imaging confirmed pregnant sharks (n=14) in various stages and residence time was quantified to identify essential reproductive habitats. Sand tigers displayed seasonal and year-round residency in North Carolina surrounding Cape Fear-Cape Lookout during Oct 2017- Nov 2019. Continuous residence times (CRT) at finer spatial scales (individual reefs) were typically short (0-2 days), but occasional longer residences (2+ weeks) hint at strong fidelity within seasons (CRT = 0-87 days). Extensive movements were also observed in individuals along the western North Atlantic during spring and fall months with all individuals returning to North Carolina.

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Study of nearshore great white shark behavior off the coast of Cape Cod using drone based tracking methods with implications for public safety.

*Kristian Sexton, Koppi Kolyvek, Robert Holt, John Reuland ​ ​

Moosh Systems [email protected]

The seal population on Cape Cod has exploded over the last several decades leading to the presence of a large great white shark population with great whites regularly swimming and hunting in areas frequented by recreational water users. This scenario had tragic consequences in the summer of 2018, with two great white attacks over a three-week period resulting in one fatality and one near fatality. The present study aims to understand the behavior and swimming patterns of great white sharks in near-shore cape cod waters.

The large great white population as well as the relatively shallow waters make Cape Cod an unparalleled location for the study of great whites using drones. Over the summer of 2019 drones were used to locate and track sharks from July through early November along a number of Cape Cod ocean beaches. Somewhere in the vicinity of fifty hours of great white footage was collected. Custom software was developed to determine shark position, swim speeds, distances from shore, movement relative to shore, shark lengths and tail beat frequencies. A number of interactions with seals were also observed. Great whites were seen to travel largely parallel to shore for extended distances with movement to and from deeper offshore waters limited. The observations contained in this study will be of the utmost importance for the development and deployment of technologies to enhance the safety of recreational water users.

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Spatial distribution and connectivity of lemon sharks (Negaprion brevirostris) in the northwest Atlantic

*Kessel ST (1), Kohler NE (2), Casey JG (2), Brooks JL (3,4), Feldheim KA (5), Rutzen H (4), Sawyna J (1), ​ ​ Frazier B (6), Gruber SH (7)

(1) Shedd Aquarium, (2) National Marine Fisheries Service, (3) Carlton University, (4) American Shark Conservancy, (5) Field Museum, (6) College of Charleston, (7) Bimini Biological Field Station Foundation [email protected]

The long-term distribution and connectivity of lemon sharks in the Northwest Atlantic region was investigated using acoustic telemetry, satellite telemetry, mark recapture and genetic analysis. Lemon sharks (Negaprion brevirostris; n = 164) were tagged in Jupiter, FL and Bimini, Bahamas, and tracked using the Vemco acoustic telemetry system and Pop-off Satellite Archival Tags (PSAT) from 2007. This data was combined with all National Marine Fisheries Service (NMFS) Cooperative Shark Tagging Program (CSTP) lemon shark records (3,574 tagged with 284 recaptured) from 1970 onwards. In chorus, these data revealed seasonal north-south migrations along the U.S. eastern seaboard >800 km, movements in excess of 1,000 km straight line distance, and connectivity between the U.S., Bahamas, Gulf of Mexico and Caribbean regions. These findings are consistent with those of mitochondrial DNA analysis that also suggested distinct breeding groups with a limited amount of connectivity. Despite the longevity, sample size, and reduced effort bias of the mark recapture study, the largest movements were documented through acoustic telemetry detections, highlighting the great advantages of system compatibility and data sharing through acoustic telemetry network groups. This study represents the most comprehensive description of lemon shark spatial distribution in the Northwest Atlantic.

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Testing Errors of Light Geolocations from Pop-Up Satellite Archival Transmitting Tags Deployed on a Coastal Marine Species

*Farrugia TJ (1), Lowe CG (1), O'Sullivan J (2) ​

(1) California State University Long Beach, (2) Monterey Bay Aquarium ​ [email protected]

Pop-Up Satellite Archival Transmitting (PSAT) tags are ubiquitous in marine ecology and very useful for collecting large amounts of fisheries-independent data on individual animals. But the spatial coarseness of PSAT light geolocation estimates and the associated uncertainties can lead to erroneous conclusions if not properly taken into account. To illustrate this issue, we analyze a unique dataset of juvenile white sharks double-tagged with both PSAT and Smart Position and Temperature (SPOT) tags to ground-truth PSAT-based light geolocation. Assuming that the SPOT positions are accurate within the manufacturer specifications, PSAT estimated positions were on average 66 km from the SPOT position, although the maximum distance was 436 km. There was also a directional bias towards the southwest for the SPOT to PSAT positional difference. From these data, we recommend that users of PSAT geolocation data present probability distributions of the position estimate rather than point estimates to avoid erroneous conclusions about the movement behavior and habitat use of tagged fish.

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Session 2: Behavior

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Scalloped hammerhead sharks swim on their side with diel shifts in rolling behavior and swimming performance

*Royer M (1), Maloney K (1), Meyer C (1), Cardona E (2), Payne N (3), Whittingham K (4), Silva G (5), ​ ​ Blandino C (1), Holland K (1)

(1) Hawaiʻi Institute of Marine Biology, (2) Bangor University, (3) Trinity College Dublin, (4) Whitman College, (5) Federal University of São Paulo [email protected]

While most sharks maintain an upright posture while swimming, it has been demonstrated that great hammerhead sharks (Sphyrna mokarran) spend most of the time swimming on their sides, presumably for greater hydrodynamic efficiency by utilizing their dorsal fin as a lift-generating surface. Like great hammerheads, scalloped hammerhead sharks (Sphyrna lewini) also have proportionally taller dorsal fins compared to pectoral fins than most shark species and thus might exhibit similar rolling behavior. This was assessed by deploying multi-sensor accelerometer instrument packages on free swimming adult scalloped hammerhead sharks to directly measure swimming depth, body orientation and swimming performance. Specific objectives were to (1) determine whether scalloped hammerhead sharks exhibit side swimming and rolling behavior, (2) characterize the patterns of these behaviors, and (3) evaluate the purpose of these behaviors. We obtained 196.7 total days (4720 hours) of data from 9 free-swimming adult scalloped hammerhead sharks equipped with multi-instrument biologgers with deployment durations ranging from 7 to 29 days. We observed rolling behavior in scalloped hammerhead sharks similar to that observed in great hammerhead sharks. In addition to an increase in degree of roll and roll duration, overall dynamic body acceleration (ODBA) also increased at night and tailbeat frequency was more regular and consistent than during daytime. These changes are possibly due to shifts from more directional swimming at night to more tortuous swimming during the day.

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Combining Movement Behavior and Environmental Data to Delineate Potential Essential Habitat for Migratory Elasmobranchs

*Bangley C (1,2), Ogburn MB (1) ​

(1) Smithsonian Environmental Research Center, (2) Dalhousie University [email protected]

Though highly migratory sharks and rays can range over entire coastlines and ocean basins, many species repeatedly use discrete areas of essential habitat that provide foraging opportunities, nurseries, and other important functions. The location, spatial extent, and timing of these areas may be defined more by oceanographic conditions than static geographic features. Delineating habitat based on environmental characteristics can inform fishery management and conservation policies, identify areas where multiple species may interact, and predict potential range shifts in response to climate change. Highly migratory species often show changes in movement behavior in certain habitats, usually defined by a reduction in travel distance and straight-line movement and an increase in residence time in a particular area. With this in mind, we developed a modeling approach using a combination of animal movement behavior and environmental data with the goals of identifying environmental associations with changes in movement behavior and using these associations to spatially delineate areas of potential essential habitat. To accomplish this, we summarized acoustic telemetry detections as daily mean positions and used state-space modeling to identify migratory (long distance, high speed) and non-migratory (short distance, low speed) movement behaviors. We then extracted remotely-sensed environmental data at the daily positions and used them to develop predictive models of non-migratory movement behavior based on environmental conditions. Here we demonstrate this approach to delineate habitat for three species with overlapping distributions in the U.S. Mid-Atlantic Bight: the dusky shark (Carcharhinus obscurus), the smooth dogfish (Mustelus canis), and the cownose ray (Rhinoptera bonasus).

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Map-like use of earth’s magnetic field in sharks

*Keller B (1), Putman NF (2), Grubbs RD (1), Murphy T (3) ​ ​

(1) Florida State University Coastal and Marine Laboratory, (2) LGL Ecological Research Associates, (3) Florida State University, National High Magnetic Field Laboratory [email protected]

Migration is common in marine animals and use of the map-like information of earth’s magnetic field appears to play an important role in navigation. Whilst sharks are iconic migrants and well-known for their sensitivity to electromagnetic fields, whether this ability is used for navigation is unresolved. Here we use a “magnetic displacement” experiment to show that sharks can use the map-like information from earth’s magnetic field to orient. Bonnethead sharks (Sphyrna tiburo) captured along the panhandle of Florida and exposed to a southern field within their range in the Gulf of Mexico oriented homeward, whereas orientation was random when exposed to a northern field outside of their range (in the continental U.S.A.) and in a field that controlled for nonspecific effects of the testing procedure. Given that sharks could have experienced more southern magnetic fields than the test site, but never more northern fields, our findings are consistent with the hypothesis that sharks learn magnetic features for navigational tasks. We further show that use of a magnetic map to derive positional information contributes to the genetic structure of bonnethead populations in the northwest Atlantic. These results offer a compelling explanation to the puzzle of how migratory routes and population structure are maintained in marine environments, where few physical barriers limit movements of vagile species.

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Foraging aspects of Cookiecutter Shark (Isistius spp.) in an equatorial Mid-Atlantic archipelago

*dos Santos BT, Veloso J, Macena B, Hazin F ​ ​

Universidade Federal Rural de Pernambuco [email protected]

The Cookiecutter Shark (Isistius ssp.) is a small squaloid shark found in the pelagic waters of tropical and sub-tropical oceans. The shark’s unique mouth, teeth and tongue morphology leaves a circular bite on their preys. However, very little is known about their foraging ecology and population. The present study aimed to understand the Cookiecutter Shark foraging ecology through the patterns and frequency of bite scars on fishes in Saint Peter and Saint Paul Archipelago (SPSPA). Many pelagic fishes were caught by the commercial fleet that operates nearby SPSPA, some of them presented wounds from cookiecutter shark bites. The number of bites, diameter, and healing stage were assessed. Based on the high frequency of bite scars, the Wahoo (Acanthocybium solandri) was selected for further analysis. The estimated size of sharks that inflicted bites on pelagic fish was calculated from the diameter of bite scars, by using a linear regression of the shark’s mouth width (MW) .vs total length (TL) TL= 4.5 (MW) + 82.8, where TL is shark total length (mm) and MW is shark mouth width (mm). A total of 100 Wahoos were analyzed; the wounds were found on lateral (71.6%), ventral (21.7%) and dorsal (6.7%) sides. The estimated size of the Cookiecutter Sharks that inflicted wounds ranged from 127 mm to 308 mm TL, and average size was 210 ±35 mm, suggesting the Wahoos were attacked by rather large sharks, for the species. The present study provides an insight into the foraging ecology of this elusive species.

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Reverse diel vertical movements of oceanic manta rays off the northern coast of Peru and implications for conservation

*Andrzejaczek S (1), Schallert R (1), Forsberg K (2), Arnoldi N (1), Cabanillas M (3), Purizaca W (2), Block ​ ​ B (1)

(1) Stanford University, (2) Planeta Océano, (3) Federal University of Rio Grande [email protected]

An understanding of the vertical movements of elasmobranchs across their range is crucial to defining critical habitat use, its overlap with anthropogenic activities, and subsequently managing such interactions. In this study, satellite telemetry was used to investigate the vertical habitat use of three oceanic manta rays (Mobula birostris) tagged on the northern coast of Peru. All three oceanic mantas exhibited patterns of reverse diel vertical migration, where vertical movements were significantly deeper at night than the day, as well as an overall preference for surface habitats (< 2 m). High resolution archival data (3-5 s) from two recovered tags revealed fine-scale behaviours, where individuals predominately remained in surface waters throughout the day, and oscillated up and down through a highly stratified water column at night. Our results suggest that coastal vertical movements were motivated by a combined foraging and thermal recovery strategy, whereby oceanic mantas dived to the seabed to forage on demersal zooplankton at night and returned to surface waters to rewarm between dives, indicating that the coast of northern Peru may be a critical foraging habitat for these animals. High use of surface waters here, however, may put oceanic mantas at high risk to several anthropogenic impacts such as vessel strike, entanglement with fishing gears, and unregulated tourism activities. Increased sample size and the use of other techniques, such as stable isotope analyses and animal-borne cameras, are required to validate our foraging and thermal recovery hypothesis and confirm this region as a foraging hotspot.

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Collective swimming kinematics of Carcharhinus limbatus to Sphyrna mokarran during wild predation events

*Ruddy BT, Kirwan DJ, Kajiura SM, Porter ME ​

Florida Atlantic University [email protected]

Schooling, or polarized collective movement, is hypothesized to provide increased predator awareness to individual fish. Based on previous in-lab experiments, swimming kinematics of prey are influenced by predator distance and neighbor interactions. We aimed to examine distances among animals, excitation wave initiation, and swimming kinematics during wild predation events using the great hammerhead (Sphyrna mokarran; predator) and blacktip shark (Carcharhinus limbatus; prey). We predicted that individual blacktip sharks would initiate escape kinematic outputs in an excitation wave, or Trafalgar effect, that would propagate throughout the group starting nearest to the predator This would result in delayed initiation and decreased kinematic variables for further individuals. We used an aerial drone to capture footage of wild predation events (N=10) between blacktips and great hammerheads. Using Loggerpro motion tracking software, we calculated kinematic variables (peak to peak amplitude, tailbeat frequency, velocity, and whole-body curvature) of hammerheads and individual blacktips within a group. ImageJ was used to quantify nearest-neighbor and prey-predator distances. Distance from the hammerhead was a significant effect in initiation of escape. We found increases in blacktip body curvature, velocity, tailbeat frequency, and initiation of the Trafalgar effect when within 3 body lengths of the predator. Within the excitation wave, blacktip sharks positioned closer to the hammerhead demonstrated increased values for body curvature, tailbeat frequency, and velocity compared to sharks further from the predator. These data show the Trafalgar effect is paired with changes in swimming kinematics that vary depending predator distance in wild sharks.

19 2020 Virtual Annual Meeting of the American Elasmobranch Society - Abstracts

Day 2 (November 14th, 2020)

Session 1: Policy and Human Dimensions of Shark Fishing ​

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Recreational shark fishing in Florida: how early career research and strategic science communication changed the law to protect threatened species

*Shiffman DS

Arizona State University, David Shiffman Consulting, INC. [email protected]

In July 2019, after nearly a decade of scientists, conservationists, and concerned citizens calling for change, Florida's Fish and Wildlife Conservation Commission enacted new regulations to protect threatened shark species from harmful angling practices. This case study, published this spring in Conservation Science and Practice, details how science conducted by graduate students and strategic communication of that science helped change laws to protect threatened species. It focuses on what skills are needed for early career researchers who want to use their expertise to change policy.

20 2020 Virtual Annual Meeting of the American Elasmobranch Society - Abstracts

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Balancing conflicting needs in the sustainable management managing of U.S. Atlantic shark fisheries

*Brewster-Geisz K, Curtis T, DuBeck G ​ ​

Atlantic Highly Migratory Species Management Division, National Marine Fisheries Service [email protected]

In the Atlantic waters of the United States Exclusive Economic Zone, the National Oceanic and Atmospheric Administration’s (NOAA) National Marine Fisheries Service (NMFS) currently manages 43 species of sharks from the Gulf of Maine through the Gulf of Mexico, including the Caribbean Sea. These species are managed under a fishery management plan that is consistent with U.S. laws. The regulations put into place under this plan, including permitting and reporting requirements, annual catch limits, possession limits, and fishing gear restrictions, have been fairly successful in that a number of species are rebuilding or have a healthy status. However, in rebuilding predators, we are now facing other challenges where we are being asked to find ways to curb depredation events. Additionally, because some species remain overfished or are still experiencing overfishing, we are also being asked to increase regulations on shark fishermen. This presentation will summarize some of the changing challenges in managing this dynamic fishery.

21 2020 Virtual Annual Meeting of the American Elasmobranch Society - Abstracts

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When fishing bites: Quantifying angler response to shark depredation

*Casselberry GA (1), Markowitz EM (2), Skomal GB (3), Danylchuk AJ (1) ​ ​

(1) Department of Environmental Conservation - University of Massachusetts Amherst, (2) Department of Environmental Conservation - University of Massachusetts Amherst, (3) Massachusetts Division of Marine Fisheries [email protected]

With shark populations showing signs of recovery in the United States, there is increased potential for shark-angler interactions and depredation in recreational fisheries. This can result in increased mortality for target fish species, changes in shark behavior, and changes in angler attitudes towards sharks. The impacts of depredation in recreational fisheries are dramatically understudied compared to commercial fisheries. Furthermore, sharks can be a polarizing topic among anglers, with some perceiving them as a threat to their catch and others valuing their ecosystem importance. To better understand angler perceptions and reactions to depredation, we distributed an online survey to North American anglers from July 2019 – January 2020, receiving over 500 responses from anglers and professional fishing guides. Overall, 77% of respondents experienced at least one depredation event in the last five years, with tunas (Thunnus spp.), king mackerel (Scombermorus cavalla), and snappers (Lutjanus spp.) lost most frequently. Survey results reveal that emotional and behavioral responses to depredation were dependent upon whether or not an angler was a fishing guide. Guides tended to feel more extreme negative emotions, including sadness and anger. Guides were significantly more likely to target and harvest sharks in response to depredation, while non-guides reported no change in behavior. Guides overwhelmingly reported that depredation had a negative effect on their livelihood with 86% having experienced depredation with clients. Overall, these results can be used to inform strategies to reduce conflict among stakeholder groups, particularly anglers, guides, and those advocating for shark conversation.

22 2020 Virtual Annual Meeting of the American Elasmobranch Society - Abstracts

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The who, what, where, and how-many of shore-based shark fishing in Florida, USA.

*Brooks JL (1,2), Guay J (3), Nguyen VM (3), Chapman J (4), Tabatabai D (5), Cooke SJ (1), Medd H (2) ​ ​

(1) Fish Ecology and Conservation Physiology Lab, Department of Biology, Carleton University, (2) American Shark Conservancy; (3) Institute of Environmental and Interdisciplinary Science, Carleton University, (4) School of Public Policy & Administration, Carleton University, (5) Recreational Angling Guide [email protected]

Shore-based shark anglers (SBSF) often target and release coastal shark species including the IUCN listed ‘Critically Endangered’ great hammerhead (Sphyrna mokarran) and has gained recent attention in the conservation advocacy realm in the USA. To address the contentious issue, the Fish and Wildlife Conservation Commission hosted several public workshops around Florida and created an online comments forum to hear the opinions of the stakeholders. Using these discussions, they created new regulations for the fishery, which includes a course-based permit. However, we argue that this fishery occurs in remote locations and most often during the night, and therefore rarely conducive to enforcement and creel-survey sampling efforts. As such, we have opted to take a bottom-up approach and collaborate with the angling community to tag and release great hammerheads from shore to produce post-release mortality estimates and to determine the most responsible angling practices that increase the chances of survival post-release. We surveyed 1500 SBSF permit-holders and will present our survey findings of the socio-economic status of the SBSF, angler perceptions and attitudes towards hammerhead shark conservation and SBSF management practices, and gear types typically used to target great hammerheads. We also present results of our ongoing satellite tagging study.

23 2020 Virtual Annual Meeting of the American Elasmobranch Society - Abstracts

Session 2: Effects of shark fishing and trade

.18……………..……………..……………..……………..……………..……………..…………………... ​ ​

Three-Dimensional Movements and Bycatch Susceptibility of Young-of-the-Year White Sharks in a Summer Nursery Area

*Curtis T (1), Shaw R (2), Galuardi B (1), Metzger G (3), Fischer C (4), McCallister M (2), Ajemian M (2) ​ ​

(1) NOAA Fisheries, (2) Harbor Branch Oceanographic Institute, (3) South Fork Natural History Museum, (4) OCEARCH [email protected]

Coastal waters off the south shore of Long Island, New York are a summer nursery area for young-of-the-year (YOY) white sharks (Carcharodon carcharias). To gain insights into movements, habitat selection, and fishery interaction potential in this region, we deployed fin-mounted satellite-linked transmitters (N=22) and 28-day high-rate pop-up satellite archival tags (PSATs, N=14) on white sharks (119-160 cm fork length) during July and August 2016-2019. Seven of these individuals were dual-tagged allowing reconstruction of three-dimensional movement paths. Vertical behavior varied between individuals and locations across the nursery area suggesting site-specific foraging strategies. Depth and temperature time-series data revealed vertical oscillations between the surface and bottom, as deep as 200 m and temperatures of 6-26 °C, but the sharks spent the majority of their time swimming at depths of 9 m (± 6 m), and in water temperatures of 19 °C (± 1 °C). Observed bycatch of YOY white sharks is infrequent, but mostly associated with bottom-tending gears in this region, including otter trawl, sink gillnet, and hook gear targeting demersal species. Thus, distance from the sea floor was calculated for the tagged sharks allowing estimation of the vertical component of bycatch susceptibility. Approximately 16% of the time was spent within 5 m of the bottom where bycatch susceptibility is greatest. Low spatiotemporal overlap with fishing effort combined with low vertical availability to bottom-tending gear provides fishery-independent corroboration of the low observed bycatch rates of YOY white sharks in fisheries in this nursery area.

24 2020 Virtual Annual Meeting of the American Elasmobranch Society - Abstracts

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Tracking the fin trade: genetic identification of supply chain starting points for three CITES-listed shark species

*Cardeñosa D (1), Fields A (1), Shea S (2), Feldheim K (3), Chapman D (4) ​ ​

(1) Stony Brook University, (2) BLOOM Association, (3) The Field Museum, (4) Florida International University [email protected]

Fins from highly mobile shark species entering large shark fin trade hubs can originate from various geographical locations and stocks. Tracking fins from internationally regulated species to their starting points in the supply chain can have important implications for the monitoring of the international trade and for assessing emerging management and conservation measures for exploited sharks. Here we use scalloped hammerhead shark (Sphyrna lewini), silky shark (Carcharhinus falciformis) and pelagic thresher shark (Alopias pelagicus) samples (N= 802) collected during a four-year period (2014-2017), and phylogenetic analyses to determine the relative contribution of these species to the largest fin trade hubs in the world, Hong Kong and Guangzhou, China. Our results suggest that the Eastern Pacific is a major starting point of the supply chain of scalloped hammerhead and pelagic thresher shark fins. Furthermore, we found that all of the silky shark samples originated from the Indo-Pacific and none were from the Atlantic. The absence of unambiguous Atlantic-origin fins from silky sharks in both Hong Kong and Guangzhou markets is consistent with the possibility that the ICCAT retention ban in Atlantic tuna fisheries, that was implemented in 2011, is largely being followed. We suggest that capacity building investments are needed in Eastern Pacific countries to increase the efficiency of border control inspections and improve the enforcement of international trade regulations. This study highlights the utility of phylogeographic data combined with large market surveys of wildlife products to better understand international trade flows and effectively implement shark fisheries management and trade restrictions.

25 2020 Virtual Annual Meeting of the American Elasmobranch Society - Abstracts

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Measurement of 1α-hydroxycorticosterone (1αOHB): Correlations with Secondary Stress Markers in Aquarium-Managed, Semi-Wild and Wild Populations of Rays and Carcharhinid Sharks

*Wheaton CJ (1), Burns CM (1), Smukall MJ (2), Hendon J (3), Mylniczenko ND (1) ​ ​

(1) Disney’s Animals, Science and Environment, Walt Disney World, (2) Bimini Biological Field Station Foundation, (3) The University of Southern Mississippi, Gulf Coast Research Laboratory [email protected]

Measurement of 1α-hydroxycorticosterone (1αOHB) has been of significant biological interest and scientific challenge for >50 years. Currently, elasmobranch stress evaluations have been limited to behavior and secondary stressors, primarily blood gasses. Since commercial enzyme immunoassays (EIA) for corticosterone exhibit only low relative cross-reactivity to 1αOHB (<5%), a monoclonal antibody and in-house EIA was developed and used to validate and optimize extraction methods and measurement of 1αOHB in <1ml blood sample without HPLC. Banked serum and plasma samples collected from aquarium-managed (Aq; The SEAS with Nemo &Friends®), semi-wild (SW; habituated; Disney Castaway Cay), and wild (W) elasmobranchs from a range of species and populations (Gulf of Mexico; The Bahamas) were tested: Hypanus americanus (Aq/SW/W); Pastinachus sephen (Aq); Sphyrna tiburo, Sphyrna lewini (Aq/W); and wild Carcharhinus brevipinna, Carcharhinus leucas, Carcharhinus limbatus, Galeocerdo cuvier and Rhizoprionodon terraenovae. Measured 1αOHB was used to assess variability between species, populations, health conditions (eg. illness, injury), and correlations with secondary stress blood values. Initial findings show that 1αOHB: 1) has species-specific concentrations and ranges; 2) exhibits a reduced range in habituated populations; 3) is elevated during illness or injury; and 4) increases in a linear fashion with species-specific changes in blood glucose and lactate values, and decreased pH. Together, these data provide increasing support for a stress hormone role for 1αOHB in elasmobranchs. Measurement of 1αOHB may be a valuable tool to evaluate stress hormone physiology, health and welfare in collection, transport, medical treatment and conservation management of these charismatic and ecologically important species.

26 2020 Virtual Annual Meeting of the American Elasmobranch Society - Abstracts

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Plasma 1α-hydroxycorticosterone measurements in Tiger (Galeocerdo cuvier) and White (Carcharodon carcharias) sharks during scientific sampling, tagging, and release

*Newton AL (1), Mylniczenko ND (2), Hyatt MW (1), Curtis TH (3), Metzger G (4), Fischer C (5), Wheaton ​ ​ CJ (1)

(1) Wildlife Conservation Society, (2) Disney’s Animals, Science and Environment, Walt Disney World, (3) National Marine Fisheries Service, (4) South Fork Natural History Museum and Nature Center, (5) OCEARCH [email protected]

The effectiveness of conservation strategies and scientific sampling protocols that involve handling and live release of fishes can be heavily impacted by post-capture mortality. Changes in blood biochemistry and acid-base parameters are frequently used to infer the magnitude of the physiologic response to fishing or sampling events and predicting post-release survival. Evidence suggests these changes may not successfully forecast outcomes following release as species specific differences in metabolic capacity and the nature and severity of an event confound interpretation when used alone. One-alpha hydroxycorticosterone (1αOHB) is the dominant corticosteroid produced by elasmobranch interrenal tissue in response to catecholamine release. It is an important ionoregulatory and stress hormone and may be a better indicator of the physiological response to handling than previous biomarkers. We used a monoclonal antibody-based enzyme immunoassay (EIA) to measure plasma 1αOHB in two elasmobranch species, tiger shark (N=9) and white shark (N=38) during routine biological sampling and tagging studies. The data were paired with blood collection for health, stress physiology and other life history studies. Plasma 1αOHB levels were compared by species, age, gender, and handling type. Concentrations were also compared over the course of the handling event (two time points) (N=24) and in conjunction with other health biomarkers. Correlation between 1αOHB values and traditional blood chemistry (lactate), acid-base (pH, HCO3) and blood gas (pCO2) alterations used to monitor stress response were explored. Both species demonstrated detectable but low concentrations of 1αOHB that did not significantly change during the course of the tagging and assessment.

27 2020 Virtual Annual Meeting of the American Elasmobranch Society - Abstracts

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The open access hammerhead shark fishery in Trinidad, food for thought

*Kingon KC (1), Ramdoo T (1), Steele AM (1), Wilson A (1), Barker AM (2), Portnoy DS (2), Grubbs RD ​ ​ (3), Douglas E (1,4)

(1) University of Trinidad and Tobago, Centre for Maritime and Ocean Studies, Chaguaramas, Trinidad and Tobago, (2) Texas A&M University–Corpus Christi, Dept. of Life Sciences, Corpus Christi, Texas, USA, (3) Florida State University Coastal and Marine Laboratory, St. Teresa, Florida, USA, (4) Sky Eco-Development Organisation, Curepe, Trinidad and Tobago [email protected]

Hammerhead shark populations are threatened globally primarily by overfishing as targeted catch and bycatch. Trinidad and Tobago’s hammerheads are no exception given the current open access fishery. Shark meat is commonly consumed in Trinidad and hammerheads make up a large percentage of the shark fishery. Species level data for hammerheads are lacking providing the impetus for this study. We interviewed shark fishers using a standardized questionnaire and collected demographic data on hammerheads at fish markets and landing sites across Trinidad. Fishers provided information on their hammerhead catch including species, sizes, numbers, locations and seasons. The questionnaires revealed that most hammerheads caught were juvenile Sphyrna lewini. Abundant landings occurred along the north coast from January to March. The majority of fishers (88%) agreed that hammerhead populations are declining in Trinidad. Demographic data confirmed the reports of the fishers that most of the hammerheads consisted of juvenile S. lewini caught along the north coast, however we also encountered large catches in Guayaguayare in southeast Trinidad. Neonates with open umbilical scars were encountered and only a few adult males and no adult females. On multiple occasions catches from individual fishing vessels were estimated to exceed 500kg of juvenile S. lewini. Our results suggest that fishers are targeting pupping grounds/nursery habitats along the north and southeast coasts. Management measures are desperately needed, such as switching to more sustainable fishing techniques, seasonal and area closures and incentivising the consumption of alternative protein sources to hammerheads. Further studies are necessary to improve management decisions.

28 2020 Virtual Annual Meeting of the American Elasmobranch Society - Abstracts

Session 3: At-risk species and habitats

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Reducing captures of evolutionarily distinct and globally endangered (EDGE) thresher sharks in Western Indonesia

*Ichsan M (1), Ula S (2), Booth H (3), Herman (4), Dharmadi (5) ​

(1) Fondation Segre’ Fellow - ZSL’s EDGE of Existence Programme, (2) Wildlife Conservation Society - Indonesia Program, (3) Department of Zoology, The Interdisciplinary Centre for Conservation Science, University of Oxford, (4) Agency for Marine and Fisheries Research and Human Resources - Ministry of Marine Affair and Fisheries, (5) Fisheries Research Centre - Ministry of Marine Affairs and Fisheries. [email protected]

Indonesia is the world’s largest shark (Class Chondrichthyes) fishing nation. Amongst the most commonly caught species are the pelagic thresher sharks (Alopias pelagicus), which is evolutionarily-distinct and ​ ​ globally-endangered (EDGE) species. According to national production statistics, Aceh province is Indonesia’s largest shark-producing province, and a hotspot for pelagic thresher shark catches, though details on the drivers of these catches and potential management options are limited. This research aimed to 1) characterize shark fisheries in Southwest Aceh District (a data-poor region) using an interdisciplinary approach, and 2) identify management options for the EDGE pelagic thresher sharks. We found 25 vessels targeting sharks in Southwest Aceh, which operate from two main landing sites. Shark fishing boats are ​ small-scale (<30 GT) and use bottom longline gears to target sharks in waters around North and West Sumatera Province. Landings monitoring shows that 34 sharks and ray species are captured, including two species of thresher shark. From June 2019 to July 2020, 93 individuals of pelagic thresher sharks were recorded in a daily landing monitoring. Of these pelagic thresher sharks, which were all mature adults and predominantly female. Based on semi-structured interviews with communities, sharks are predominantly targeted for their fins, which are sold internationally. Other body parts are generally considered a ‘by-product’, although shark meat has importance as a local food source (shark curry is a traditional delicacy served during ceremonies). A technical assessment indicates that pelagic thresher shark catches could be reduced by depth limits, effort limits or trip quotas with live release protocols. However, further information on the drivers of thresher shark capture and their socio-economic importance is required to understand the feasibility of implementing these measures.

29 2020 Virtual Annual Meeting of the American Elasmobranch Society - Abstracts

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Urban Manta Rays: Potential Manta Ray Nursery Habitat along a Highly Developed Florida Coastline

*Pate J, Marshall, A ​ ​

Marine Megafauna Foundation [email protected]

The oceanic manta ray (Mobula birostris) was listed on the U.S. Endangered Species Act as a “Threatened” species in 2018, yet insufficient data exist on manta populations throughout U.S. waters to designate critical habitat. Taxonomic and genetic evidence suggests that manta rays in the Western Atlantic are a separate species (M. cf. birostris) and little is understood about the ecology and life history of this putative species. The juvenile life stage of both, M. birostris and M.cf. birostris, is particularly under-studied. Here, we are the first to describe the characteristics of a manta ray population along a highly-developed coastline in southeastern Florida using boat-based surveys and photo identification of individuals. Fifty-nine manta individuals were identified between 2016-2019. All males were sexually immature based on clasper development, and 96% of females were classified as immature based on size and absence of mating scars or visible pregnancies. Twenty-five (42%) individuals were observed more than once during the study period and eight individuals were sighted over multiple years. The occurrence of juveniles, high site fidelity and extended use of the study area by juvenile manta rays suggests southeastern Florida may serve as a nursery habitat. High occurrence of fishing line entanglement (27% of individuals) and vessel strike injury were documented and rapid wound healing was observed. Future research and conservation efforts will focus on identifying the physical and biological features of the potential nursery habitat and mitigation of anthropogenic impacts.

30 2020 Virtual Annual Meeting of the American Elasmobranch Society - Abstracts

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Home sweet home: site fidelity of the reef manta ray to a remote coastal bay in the Sudanese Red Sea

*Knochel A (1), Cochran J (1), Braun C (1), Klaus R (2), Chekchak T (3), Hill G (4), Alhasan N (5), Younnis ​ ​ M (1), Kessel S (6), Hussey N (7), Berumen M (1)

(1) KAUST, (2) PERSGA, (3) Equipe Cousteau, (4) The Deep Aquarium, (5) Wildlife Conservation General Administration, (6) Shedd Aquarium, (7) University of Windsor [email protected]

Reef manta (Mobula alfredi) populations along the east African coast are poorly studied and likely in decline. Identifying critical habitats for this species will be essential for future research and conservation efforts. Dungonab Bay, a marine protected area and UNESCO World Heritage Site, hosts the largest known reef manta aggregation in the Red Sea. Here we present approximately two years of passive acoustic telemetry monitoring from this site using data collected from 19 individuals and 16 strategically placed receivers. These data are used to quantify long-term residency and seasonal shifts in habitat use. Additionally, acoustic telemetry combined with satellite telemetry was used to simultaneously track three mantas. On average, individual mantas were detected within the array on 39% of monitored days. Mantas were detected within Dungonab throughout the year, though some individuals were occasionally absent from the receiver array for weeks at a time and generalized additive mixed models showed a clear seasonal pattern in detection probability. The highest probabilities occurred in boreal fall (~80% chance of detection) while the lowest occurred in boreal spring (~30%). Modeled biological factors, including sex and disc width, had no influence on animal presence. Despite the high residency suggested by acoustic telemetry, satellite telemetry recorded mantas making excursions outside of the bay, including tracks up to 80 km away from Dungonab. This study adds to growing evidence that reef mantas are highly resident but display seasonal shifts in movements that are likely dependent on resource availability and the oceanography of their home range.

31 2020 Virtual Annual Meeting of the American Elasmobranch Society - Abstracts

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Conservation priority shark species display higher abundances within a marine reserve in a global biodiversity and fishing hotspot

*Albano P (1), Fallows C (2), Fallows M (2), Schuitema O (1), Bernard A (3), Sedgwick O (2), Hammerschlag ​ ​ N (1)

(1) University of Miami, (2) Apex Shark Expeditions, (3) South African Institute for Aquatic Biodiversity [email protected]

As marine conservation planning efforts promote MPA establishment worldwide, there remains a weakness in their application as tools to protect imperiled shark species in global biodiversity hotspots that overlap with fishing pressure. Although the effectiveness of MPAs for protecting certain shark species is debated, there is clear evidence that this tool could prevent future extinctions if implemented strategically as an ecologically connected network and through evaluation of existing MPAs that contain conservation priority species and habitats. Our study used baited remote underwater video surveys (BRUVS) to evaluate the drivers of shark relative abundance relative to an MPA in South Africa, a global biodiversity that is home to endemic, threatened, and data deficient species. BRUVS were deployed over a three-year period, across four habitat types, inside and outside of a no-take marine reserve to measure the effects of environmental, spatial, and management variables on shark relative abundance (in terms of community assemblage, species management status, and trophic level). Sharks were observed on 71% of BRUVS samples, totaling 403 individuals from 11 species and six families. We documented significantly greater community relative abundance inside the MPA, supporting the hypothesis that sharks would be more abundant inside the MPA than outside its boundaries which are targeted by a demersal shark longline fishery. Relative abundance inside the MPA also increased on samples that were deployed farther from the reserve’s exposed boundaries. Habitat use varied by trophic level and species management status, highlighting the importance of habitat type as a driver of shark abundance. These findings underscore the utility of MPAs for protecting conservation priority sharks and demonstrate that, when informed by species-specific data, this tool can be used to provide refuge for endemic and threatened species that are otherwise vulnerable to exploitation.

32 2020 Virtual Annual Meeting of the American Elasmobranch Society - Abstracts

Day 3 (November 21st, 2020)

Session 1: Reproduction and physiology ​

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Hannibal Shark Embryos: A case of extreme maternal investment and survival cannibalism?

*Amorim-Lopes C (1,2), Araujo NLF (2), Hauser-Davis RA (30, Neves LS (2) ​ ​ ​ ​

(1) Programa de Pós-graduação em Ecologia e Evolução, Universidade Estadual do Rio de Janeiro (2) Laboratório de Ictiologia Teórica e Aplicada, Instituto de Biociências, Universidade Federal do Estado do Rio de Janeiro, (3) Laboratório de Avaliação e Promoção da Saúde Ambiental, Instituto Oswaldo Cruz, Fiocruz [email protected]

We report herein a singular case of a gravid Rhizoprionodon lalandii female presenting no liver or intestine and exhibiting muscle lacerations in the abdominal cavity, which contained four embryos. This female was landed at Rio de Janeiro, southeastern Brazil, in June 2019, exhibiting no external injuries or cuts, and dissected fresh. Total length (TL) and weight (TW) were 665 mm and 1024 g for the female, whereas TL ranged from 256 –265mm and TW from 39 to 63g, respectively, for the embryos. Internal organ consumption by necrophagous crustaceans is improbable, since none were found inside the female’s body and the carcass showed no decomposition signs. Chronic disease is another possibility, albeit very unlikely, since the shark could not survive and generate embryos without its liver or intestine. Our putative hypothesis is of a synergistic association between maternal investment in an extreme resource remobilization and embryo survival cannibalism in the face of scarce resources. This would, in turn, result in liver suppression in order to provide embryo survival, followed by internal cannibalization by the embryos characterizing survival cannibalism behavior, possibly due to nutrient supply interruption caused by the female’s death. This hypothesis is supported by internal muscle lacerations consistent with embryo mouth sizes, ruptured oviducts, the absence of an intestine and liver, as well as previously documented high maternal litter investments by R. lalandii. Since this phenomenon has never been documented for elasmobranchs, further studies are required in order to address how extremely stressful situations affect this group's behavior.

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Influence of female size in the variation of Multiple Paternity in the brown smooth-hound shark Mustelus henlei.

*Rendón-Herrera J, Saavedra-Sotelo NC ​ ​

Autonomous University of Sinaloa [email protected]

The multiple paternity (MP) in shark species has been widely studied and discussed, leaving researchers more questions than answers regarding the evolution of reproductive behavior in sharks. The brown smooth-hound shark (Mustelus henlei), has shown a regional variation of the mating system, which has been attributed to the different population dynamics along the Northeastern Pacific. In this study, the MP was assessed in 22 litters (22 mothers and 103 embryos) at Puerto Libertad in the Gulf of California, of which 54.55% were sired by more than one male (from 2 to 4 sires). The litters presented male reproductive skew possibly due to some cryptic post-copulatory selective process as sperm selection through the oviductal gland. There were significant differences between monandrous and polyandrous females concerning body and litter sizes. Moreover, there is a relationship between fecundity (number of embryos per litter) and body size. A GLZ model showed that larger females have a higher probability of MP than smaller females. These results indicated that a combined mating system in a population can be beneficial to their survival, especially in populations subject to fishing exploitation such as the brown smooth-hound shark.

34 2020 Virtual Annual Meeting of the American Elasmobranch Society - Abstracts

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An inconvenient tooth: Evaluating female choice in multiple paternity in sharks, skates and rays

*Lyons K (1), Kacev D (2), Mull CG (3) ​ ​

(1) Georgia Aquarium, (2) Scripps Institution of Oceanography, (3) Dalhousie University [email protected]

Sexual conflict theory has been widely examined by multiple generations of scientists across taxa. As the field continues to diversify, alternative mechanisms for explaining natural phenomena are increasingly considered as we include new perspectives into the community. However, the rate of incorporation of these novel perspectives varies across fields and among study organisms, and, in some cases, dogmatic views prevail. Research of elasmobranchs traditionally lags behind other taxa, and complex biological processes such as multiple paternity are often ascribed to convenience polyandry offhand. For a field that has been, until recently, dominated by men, this de facto reasoning completely ignores the female role in complex reproductive systems. Our study challenges the dogma that multiple paternity is perpetuated by convenience polyandry in elasmobranchs, which has hampered the advancement of this field, by presenting alternative mechanisms and explanations from a female and life history perspective and advocate for more holistic approaches inclusive of both female and male biology considerations.

35 2020 Virtual Annual Meeting of the American Elasmobranch Society - Abstracts

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Multiple reproductive adaptations ameliorate pup mortality by predation in Elasmobranchii sharks

*Deeken D, Gainsbury A, Cassill DL ​ ​

University of South Florida [email protected]

Sharks are members of elasmobranch fish characterized by a cartilaginous skeleton. Sharks are distributed throughout all of the world’s oceans. It is often the case that a shark species is the apex predator in their environment. However, despite the crucial ecological role these organisms play, much yet is to be discovered regarding their reproductive propensities. The intent of this study on sharks (Elasmobrancii) is to use maternal risk-management theory as a theoretical framework for understanding the natural selection pressures that have shaped pup number, relative pup size, pup diversity, and diverse brooding tactics in sharks (oviparity, viviparity, and oviviviparity). This study analyzed data on 123 species of sharks using multivariate statistics. The maternal risk management model predicts that pup size and pup number per litter were independent maternal investments. Shark species in which offspring are threatened by predators produce a larger litter size. In contrast, shark species in which offspring are vulnerable to patchy distribution of food are threatened by starvation. In this study we found that pup size and pup number were independent. Furthermore, female size was a predictor of pup size but not pup number. Phylogeny explained a small fraction of variation in pup number. However, phylogeny did explain a larger fraction of variation in pup size. Predation pressures were found to predict the number of pups per breeding event across shark species. Additionally, both female size at maturity and prey scarcity were found to predict the size of pups at birth.

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Multimodal imaging and analysis provide new insights into the organisation of olfactory inputs in a shark model species (Chiloscyllium punctatum)

*Camilieri-Asch V, Yopak KE, Shaw JA, Partridge JC, Collin SP ​ ​

(1) The University of Western Australia Oceans Institute & School of Biological Sciences, The Queensland University of Technology Centre for Biomimetics in Bioengineering, (2) Department of Biology and Marine Biology & the Center for Marine Science, University of North Carolina Wilmington (3) Centre for Microscopy, Characterisation and Analysis - Microscopy Australia, The University of Western Australia (4) The University of Western Australia Oceans Institute, (5) The University of Western Australia Oceans Institute, School of Life Sciences, La Trobe University [email protected]

There remains a limited understanding of the morphological and functional organisation of the olfactory system in cartilaginous fishes, when compared to other vertebrates. This study examines the ascending olfactory pathway of the brownbanded bamboo shark, Chiloscyllium punctatum, by assessing the relationship between several neuroanatomical indicators of olfactory abilities. Specifically, we 1) assess brain volumetrics using an emergent X-ray computed tomography technique (diceCT), 2) estimate the level of convergence olfactory inputs to the brain using electron microscopy, 3) provide a preliminary assessment of the different olfactory receptor neuron (ORN) morphotypes, their relative abundance and distribution in the olfactory rosette, using histological and immunohistochemical techniques, and 4) correlate this with hydrodynamic modelling of incurrent water flow through the olfactory cavity. Together, the results indicate that relative olfactory bulb volume remains a reliable proxy for assessing and comparing olfactory capabilities, there are three confirmed (out of a possible six) ORN morphotypes and some evidence of a lateral segregation of primary inputs within the olfactory bulb, suggesting a potential somatotopic organisation in this species. Although most ORNs are ubiquitously distributed within the medial and lateral regions of the olfactory rosette, three microvilli-bearing types are collectively found in significantly higher densities in medial lamellae. Hydrodynamic simulations reveal that the differential distribution of ORN types across the rosette may reflect adaptations in sampling specific water-borne chemicals in this species and may guide subsequent tracking behaviour. This multimodal approach provides important quantitative data, which in turn, can inform the assessment of olfactory capabilities across a broader range of species in future.

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Session 2: Diet, pollutants, and health

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Interspecific variability in the trophic ecology of two co-habiting apex predators in coastal Texas

*Marsaly B (1), Matich P (2) ​ ​

(1) AgroCampus Ouest, (2) Texas A&M University at Galveston [email protected]

Here we study the trophic ecology of two of the most abundant top-predators in the estuaries of the North Western Gulf of Mexico: the bull shark (Carcharhinus leucas) and the alligator gar (Atractosteus spatula). Stomach contents and bulk stable isotope ratios were analyzed from predators in two estuarine systems of Texas - Sabine Lake and San Antonio Bay - to compare their trophic relationships. The two species predominantly fed on Mugilids. Juvenile bull sharks also appear to be demersal foragers based on high occurrence of red drums and catfishes in their diets. Alligator gars also fed on Clupeids attributed to their ambush tactics. Bull sharks show higher trophic positions in both estuaries. These predators exhibit overlap in their trophic interactions, but our results indicate interspecific variability suggesting various evolutionary and ecological mechanisms lead to trophic partitioning within estuaries. Understanding the trophic relationships of each top predators is crucial to comprehend their roles within estuarine food webs in Texas, and thus improve management efficiency at a community- and ecosystem-level.

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Lipid metabolites as energy stores in stingrays

*Moniz LE (1), Lyons KD (2), Hoopes L (2), Lewis JM (2), Bedore CN (1) ​ ​

(1) Georgia Southern University, (2) Georgia Aquarium [email protected]

Energetic requirements are linked to the energy animals obtain from their diets. Lipid metabolites (lipids used in metabolism) are energy dense and integrate into tissues. Triglycerides (TAG) are energy storage units and free fatty acids (FFA) and ketone bodies are sources of usable energy. Lipid metabolites are synthesized from dietary fatty acids and are influenced by the lipid content of prey. Stingrays consume a variety of prey items (teleosts, mollusks, arthropods) ranging in lipid content, but the integration of these lipids into tissues and the use of them as metabolites is poorly understood. This study aims to establish baseline concentrations of TAG and FFA in liver, plasma, and muscle tissues of three stingray species that consume different prey. Liver, muscle, and plasma samples were collected from Gymnura lessae (n= 8-12), Hypanus say (n= 8-12), and Hypanus sabinus (n= 8-12) from commercial trawls. Tissue concentrations of TAG and FFA were quantified using colorimetric assays. Gymnura lessae had significantly greater (p<0.05) liver TAG and FFA and plasma TAG concentrations than H. say and H. sabinus. There was no significant difference in muscle FFA or TAG between species. Gymnura lessae are primarily piscivores (lipid-dense) whereas the other two species are invertivores. Gymnura lessae’s muscle was likely not significantly different from other species because TAG and FFA are not the main fuel sources in muscle.

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Acute Phase Reactants in the Nurse Shark, Ginglymostoma cirratum

*Rusnak E, Hammerschlag N, Merly M ​ ​

Department of Marine Biology and Ecology, Rosenstiel School of Marine and Atmospheric Science, University of Miami, Shark Research and Conservation Program, Rosenstiel School of Marine and Atmospheric Science, University of Miami [email protected]

Overall health and wellness can be measured by a suite of biomarkers that are direct indicators of immune condition. Acute phase proteins, like C-reactive protein (CRP) and serum amyloid-P (SAP), have been extensively used as biomarkers in wellness assessments in clinical and veterinary medicine, and aquaculture practices. There does not yet exist a shark-specific biomarker assay that allows researchers to monitor captive populations or assess health in wild populations. In this study, liver tissue from healthy and sick nurse sharks, Ginglymostoma cirratum, were probed for clinically relevant acute phase proteins using molecular techniques. For the first time, a C-reactive protein-like molecule has been isolated from nurse shark genomic DNA. When compared phylogenetically with other taxa, the nurse shark CRP-like molecule grouped closest with similar proteins from elasmobranchs, bony fish, and basal teleost fish, indicating that this molecule may function differently from what is seen in the mammalian condition. In a novel case study, liver transcriptomes between a healthy and a sick nurse shark were compared, and clinically relevant immune genes were sought out within these transcriptomes. Genes in the complement and coagulation cascades were among the most significant differentially expressed genes, indicating that these pathways are critical during a shark immune response. As no major acute phase proteins (e.g. CRP/SAP) were actively expressed in the liver tissue during infection, it is suggested that complement proteins should be the focus of future work with respect to isolation of suitable shark biomarkers that could be used in clinical and wild health assessments.

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Evaluation of the heavy metal content of the Bull Shark Carcharhinus leucas off the Coast of Nigeria.

*Fola-Matthews O, Soyinka O ​ ​

Nigerian Institute for Oceanography & Marine Research, University of Lagos [email protected]

Heavy metals are of concern globally due to their high toxicity, persistence and accumulation through the food webs. Sharks species as apex predators are prone to the bio-accumulation of these metals. This study assesses the potential human health risks posed by four heavy metals (Cd, Pb, Cu, and Zn) found in the muscle and liver of the bull shark obtained from the Liverpool fish market in Lagos, South West of Nigeria. The heavy metal concentrations were determined using an atomic absorption spectrophotometer. The chronic daily intake (CDI) and the total hazard quotient (THQ) were estimated to determine the hazard indices (HI). Cadmium levels ranged between 0.003-12.23 mg/kg. Lead levels ranged between 0.04-4.04 mg/kg. Zinc levels ranged between 0.02-47.12 mg/kg and copper levels ranged between 0.03-10.05mg/kg. The THQ values of the bull sharks > 80cm in length had values over 1.0 for lead and cadmium which suggests that the consumption of this shark species is likely to pose a health risk of significant concern.

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The ChondroCensus: A New Tool for Global Collaboration and Communication

*Janssen J

National Aquarium [email protected]

The International Census of Chondrichthyans in Human Care (aka the ChondroCensus), part of the AZA SAFE: Sharks and Rays sustainability project, is a user friendly web based platform that houses and - - maintains a global census of chondrichthyans in public aquaria, research facilities, and beyond. Launched in 2019 as a reboot of the AES International Elasmobranch Census, the ChondroCensus includes 264 species from 224 facilities representing 51 countries and counting. The goals of the ChondroCenus include facilitating communication and supporting cooperative research, conservation of at risk species, and collaborative - breeding programs. With 25 global Regions, 19 Regional Coordinators have been recruited to rally and assist ChondroCensus participants. Regional Coordinators are currently being sought for Africa North, Asia Central, Australasia, Canada West, and Russia. To view any facility’s specific ChondroCensus data, website Users can apply through the website to join any facility’s Team, and the associated Team Coordinator will review that request to either grant or deny Membership onto that Team. New search and communication features will allow Users to query taxa by Region and basic husbandry information and allow the User to reach out directly to the Team Coordinators at each of those stakeholder facilities. This will remove networking obstacles and allow research queries to be more focused and therefore more effective in garnering collaborators. It is also hoped to include a blood chemistry registry by 2021. www.sharksandraysproject.com.

42 2020 Virtual Annual Meeting of the American Elasmobranch Society - Abstracts

Session 3: Genetics and evolution

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Genetic population dynamics of scalloped hammerhead sharks in the Galápagos Islands

*Harned S (1), Bernard A (1), Mehlrose M (1), Salinas P (2), Feldheim K (3), Shivji M (1) ​ ​

(1) Nova Southeastern University, (2) Darwin Foundation, (3) Chicago Field Museum [email protected]

The globally distributed, coastal-pelagic scalloped hammerhead shark (Sphyrna lewini) is widely exploited for its fins and meat. Drastic population declines have resulted in its categorization as Endangered on the IUCN Red-List and inclusion under the US Endangered Species Act. This species is famously recognized for its tendency to form seasonal aggregations of mostly adult females around seamounts and offshore islands in the Eastern Tropical Pacific (ETP), including the northern Galápagos Islands. Female scalloped hammerheads in the ETP are also known to utilize shallow mangrove bays along the Central and South American mainland for parturition. My study objectives are to determine: 1) genetic diversity of the Galapagos aggregation compared to other adult populations from the Seychelles and the Florida east coast, 2) connectivity and relatedness of Galapagos sharks and young of year (YOY) individuals from nursery areas along the coast of the ETP, and 3) the genetic relationship of the Galapagos aggregation to global hammerhead populations from previous studies. Results using seven biparentally inherited nuclear microsatellite and maternally-inherited mitochondrial DNA sequence markers show little genetic population structure and a high degree of relatedness among sharks sampled in the Galapagos aggregation and ETP nurseries, indicating high genetic connectivity in this region. Analysis is ongoing to determine genetic diversity of the Galapagos aggregation compared to other adult populations, and to understand how the Galapagos aggregation fits into the global dataset of scalloped hammerhead control region sequences. To date, this is the first genetic study of the Galapagos aggregation.

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The role of the American continent on the diversification of the stingrays’ genus Hypanus Rafinesque, 1818 (Myliobatiformes: Dasyatidae)

*Petean FF (1), Yang L (2), Corrigan S (2), Lima SMQ (1), Naylor GJP (2) ​ ​

(1) Universidade Federal do Rio Grande do Norte, (2) Florida Museum of Natural History [email protected]

Stingrays of the resurrected genus Hypanus Rafinesque, 1818 currently encompass eight valid species distributed in the Atlantic and Pacific oceans. To assess the genus’ monophyly and evaluate species divergence times and possible routes of dispersion, we sequenced whole mitochondrial genomes of all putative valid species using the gene capture methodology and performed phylogenetic Bayesian Inferences. Hypanus longus, from the Pacific coast of the Americas, is a sister-group to the clade H. berthalutzae + H. rudis by a cladogenetic event derived from the vicariant closure of Isthmus of Panama. The abovementioned clade + H. americanus species complex is a sister-group to H. marianae, endemic to Northeastern Brazil and whose phylogenetic relationships within the genus were unknown. The species complex H. guttatus, with lineages in Central and South America, probably has an event related to the Amazon barrier. Hypanus say, another species complex, comprises one lineage at the Eastern coast of the United States and another in the Gulf of Mexico. We also identified the species Fontitrygon geijskesi as more closely related to H. guttatus than to other Fontitrygon species, thus it should be allocated to Hypanus as H. geijskesi. The genus originated 33.97 Ma [26.13-36.09 HPD] and its subsequent diversification was probably related to a world cooling event in which stingrays were restricted to tropical waters in Western Atlantic. Oceanic geophysical changes are consistent with the divergence times of lineages within this group of stingrays, which harbors a hidden diversity that might affect the conservation status of some species.

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Dorsal fin mystery: Insight for shark bauplan

*Angibaud M (1), Berio F (2), Cloutier R (1), Naylor G (3) ​ ​

(1) Université du Québec à Rimouski, (2) Université de Montpellier, (3) University of Florida

The first thing, apart from the jaws, that come to mind when you talk about sharks are their dorsal fins. While the focus is on the external appearance, what is happening below the skin has not been investigated. By using 3D modelling and double coloration, we described the disparity of the skeleton of shark dorsal fins and their development. Dorsal fins are supported by two types of structures that we qualified as plate like or tube like. The arrangement of the cartilaginous structures differs between orders. The arrangement disparity seems to match the phylogenetic distances, particularly between galeomorphii and squalomorphii. Description of the development of shark dorsal fins helps to understand their modularity and offers insight to shark bauplan.

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The Skatey Bunch: Population Structure of the Clearnose Skate (Rostroraja eglanteria) in the Western North Atlantic Using SNP Genetic Markers

*Nelson LN, McDowell JR ​ ​

Virginia Institute of Marine Science, College of William & Mary [email protected]

Clearnose skates, Rostroraja eglanteria (Bosc 1800) inhabit the United States coastal waters of the western Atlantic Ocean and in the eastern Gulf of Mexico. They are seasonally migratory and are often incidentally caught in bottom trawl fisheries during times of migration and congregation, discarded at sea, and poorly accounted for in catch records. Unlike their more charismatic relatives, they have been afforded little attention by fisheries managers and conservation groups. Before implementing or improving policies, more life history research is needed. In particular, understanding population structure can aid in characterizing R. eglanteria gene flow, segregation, migration, and local adaptation, allowing managers to delimiting stocks and more accurately manage harvest. Thus, we tested whether clearnose skates consist of a single panmictic population by examining genetic variation using SNP markers. Specimens were collected by fisheries-independent surveys and categorized into one of three study regions; U.S. East Coast north of Cape Hatteras (NOR), U.S. East Coast from Cape Hatteras to Florida (SOU), and the Gulf of Mexico (GOM). DNA was extracted and shipped to Diversity Arrays Technology for high-throughput genotyping-by-sequencing. The resulting SNP data and associated specimen metadata were passed through a series of quality filters in R to produce two datasets, one comprised of 8,914 total loci and one comprised of 30 outlier loci. Results support the GOM specimens as a separate population. We were unable to definitively resolve whether structure was present along the U.S. east coast, which may be aided by more rigorous sampling in the future.

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Is blood thicker than water? Relatedness and kinship in juvenile bull sharks (Carcharhinus leucas)

*Morgan T (1), Barry S (1), Gulak SJB (2), Drymon JM (3), Seubert EA (3), Daly-Engel TS (1) ​ ​

(1) Florida Institute of Technology, (2) Riverside Technologies, Inc. NOAA, National Marine Fisheries Service, Southeast Fisheries Science Center, (3) Coastal Research and Extension Center, Mississippi State University [email protected]

The bull shark (Carcharhinus leucas) is a widely-distributed coastal species, with the unique ability to fully occupy both marine and freshwater environments. Female bull sharks are known to exhibit philopatry, returning to the same estuarine and freshwater nursery habitats to give birth, with offspring residing in these areas for several years. Proximity to coastlines leaves juveniles particularly vulnerable to anthropogenic pressures, which along with commercial and recreational exploitation has resulted in bull sharks being listed as “Near Threatened” by the International Union for Conservation of Nature (IUCN). Despite being a relatively well-studied, charismatic species, little is known about dynamics that drive bull shark reproductive behavior and distribution, especially among juveniles within enclosed nursery habitats. Here we use 20 highly polymorphic microsatellite DNA markers to describe patterns of genetic relatedness and paternity among 115 individual bull sharks from the northern Gulf of Mexico. This includes four full litters (mothers and pups) used to derive within-brood relatedness, which we compare to kinship and relatedness values among 56 putatively-unrelated juvenile bull sharks that were recovered together from a ghost net in Mobile Bay, Alabama. Understanding population dynamics in and around bull shark nursery sites, including behavioral associations among kin, is crucial to improving management and conservation of the species as a whole.

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Cryptic Speciation and Genetic Diversity in Dogfish Sharks (Genus Squalus)

*McCall C, Daly-Engel T ​ ​

Florida Institute of Technology [email protected]

Deep-sea dogfish sharks, genus Squalus, have long reproductive intervals of 24 months and slow growth rates. They have low standing genetic diversity and are often caught as bycatch, which can result in catastrophic declines and an inability to recover following depletion. Similarities in morphology among Squalus species has lead to widespread taxonomic confusion, leading to the discovery of cryptic species (genetically-distinct species with morphological differences that are difficult or impossible to distinguish). We surveyed genetic diversity and evolutionary divergence in samples from 21 putative Squalus species using two mitochondrial genes, ND2 and the control region (D-loop), and two nuclear genes, ITS2 and Rag-1. Bayesian phylogenetic analysis showed that the combination of the four genes provided better statistical support for the divergence of species than any of the genes individually, and indicated the presence of six cryptic, potentially-novel species previously identified as Squalus mitsukurii or S. megalops. The genus Squalus is currently considered Data Deficient by the IUCN, and as their phylogeny remains unclear it is possible that species with unique genetic diversity could go extinct before they are even discovered. Taxonomic evaluation is an important first step in being able to properly classify and eventually manage distinct species.

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