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    Session 22: AES Behavior/ Movement & Distribution II

    Room: Conference Theater

    2022-07-29   10:00 - 12:00

    Moderator: Kyle Newton



    1.  10:00  Movement Behavior and Habitat Use of Cownose Rays (Rhinoptera bonasus) in Apalachicola Bay, FL. Ashley Dawdy*, Florida State University; Dean Grubbs, FSU Coastal & Marine Laboratory   amdawdy@gmail.com

    The Atlantic cownose ray (Rhinoptera bonasus) is a highly migratory ray species present along the eastern coasts of North and South America and throughout the Gulf of Mexico (GoM). Due to an extremely conservative life history, R. bonasus has among the lowest maximum population increase rates of any fish. It has become increasingly difficult to manage R. bonasus due to limited behavioral data and recent identification of a morphologically identical species (Rhinoptera brasiliensis) with an overlapping geographic range. While detailed movement studies of cownose rays have been conducted along the eastern US coast, movement data for GoM individuals are lacking. There are no existing data regarding seasonal residency or movement of R. bonsasus in the Apalachicola Bay area, but recent sampling effort suggests the area serves as a pupping and mating ground for adults and potentially an important area for pups. The preliminary goals of this study are to define the extent of seasonal bay use by cownose rays and identify changes in core habitat (seagrass beds, mud flats, and oyster reef) preference and space use over ontogeny. Twenty individuals, including mature and young-of-year males and females, were tagged with passive acoustic transmitters in summer of 2021, and sixteen more will be tagged in summer 2022. Here, we present preliminary trends in space use, habitat use, and movement behavior, as well as discuss an observed mating event, for cownose rays in Apalachicola Bay.


    2.  10:15  Movement patterns of the shovelnose guitarfish (Pseudobatos productus) and California bat ray (Myliobatis californica) in the Southern California Bight. Anabelle Gong*, University of San Diego; Andrew Nosal, University of San Diego; Dan Cartamil, Scripps Institution of Oceanography; Lyall Bellquist, The Nature Conservancy; Noah Ben-Aderet, Southwest Fisheries Science Center; Kayla Blincow, University of the Virgin Islands; Echelle Burns, Univer   agong@sandiego.edu

    The shovelnose guitarfish (Pseudobatos productus) and the California bat ray (Myliobatis californica) are among the least studied ealsmobranchs in the Southern California Bight. While the movement patterns of large elasmobranch species have been studied extensively, those of smaller, mesopredatory species remain understudied. This study quantified the broad- and fine-scale movement patterns of these species using passive acoustic telemetry. Twelve guitarfish were surgically implanted with coded acoustic transmitters at a known aggregation site off La Jolla (San Diego County), California, USA and tracked for 849.5 days each, on average. Six bat rays were also implanted here and tracked for 1143.8 days each, on average. These animals were detected at 187 acoustic receiver stations between Point Conception, California, and San Quintín, Baja California, Mexico. Both species exhibited annual philopatry to the La Jolla tagging site, especially during the month of July, after traveling as far north as Santa Barbara, CA (221 km away; guitarfish) and San Miguel Island, Northern Channel Islands, California (259 km away; bat rays). Of the 34 receivers off La Jolla, a mean of 84.4% of guitarfish detections and 48.4% of bat ray detections occurred at just two acoustic receivers located on a sandflat in the lee of a submarine canyon. Guitarfish had a strong preference to soft substrate off La Jolla, while bat rays utilized both soft and hard substrates. This is the longest-duration acoustic tracking study of these batoid species to date, and the first to track California bat rays using passive acoustic telemetry.


    3.  10:30  Ecological drivers shaping elasmobranch assemblages at a near-pristine ecosystem. Marta Cambra*, Universidad de Costa Rica; Isaac Chinchilla, Área de Conservación Marina Cocos; Geiner Golfín, Área de Conservación Marina Cocos; Mario Espinoza, Universidad de Costa Rica   m.cambra.agusti@gmail.com

    Cocos Island is known to have one of the largest biomass of predatory fishes in the Eastern Tropical Pacific, yet our knowledge of the drivers affecting elasmobranch abundance and distribution patterns is limited. This study examined the effect of spatial, seasonal, and environmental drivers on elasmobranch assemblages at Cocos Island using baited remote underwater video stations (BRUVS) between 2016 and 2020 covering different seasons, habitats and depths. Elasmobranchs were detected in 95% of the BRUVS, with stations having on average 2.7 ± 1.6 species and 6.3 ± 6.5 ind/hour. The most abundant and frequent species were the hammerhead Sphyrna lewiniand the whitetip reef Triaenodon obesus sharks. Elasmobranch assemblages were structured according to habitat type, substrate cover, depth, temperature and rugosity. Significant indicator species with the highest Dufrêne-Legendre indicator values (DLI) were the silky shark Carcharhinus falciformis dominating pelagic habitats, T.obesus and black tip reef shark C. melanopterusdominating shallow (< 20 m) bays and inshore sites with high rugosity and the galapagos shark C. galapagensisdominating shallow depths at cleaning stations and pinnacles. Other species with lower DLI values (0.1 - 0.20) were S. lewini and the marble ray T. meyeni characterizing deep rocky areas and the silvertip C. albimarginatus, and the tiger Galeocerdo cuvier sharks characterizing sandy areas. Benthic elasmobranch assemblages were mainly influenced by depth level followed by rugosity, habitat, location, and season. A better understanding on how elasmobranchs use specific habitats and respond to environmental changes at near-pristine ecosystems can provide valuable insights for their conservation.


    4.  10:45  A Spatial Survey of the Sharks and Rays of Trinidad Highlighting the Threatened Species. Kelly Kingon*, University of Trinidad and Tobago; David Portnoy, Texas A&M University - Corpus Christi; Christopher Ragobar, St. Joseph's Convent Secondary School; Terryn Constantine, University of Trinidad and Tobago; Navin Kalpoo, Kalpoo's Bird Sanctuary Ibis Tours; Marc Bejai, Fisheries Division; Christopher Nakhid, University of Trinidad and Tobago; Justin Isaacs, Trinidad and Tobago Fire Service; Chelsea Mangaroo, University of Trinidad and Tobago; Daniel Naitrum, University of Trinidad and Tobago   kelly.seaweed@gmail.com

    Many elasmobranch populations are threatened with extinction, mostly due to targeted fisheries and incidental catches. The extraction rate often exceeds their ability to repopulate because of long gestations, few offspring and late maturity. This is compounded by aggregating tendencies during mating, pupping or feeding that make them more vulnerable to fisheries activities. In Trinidad, we don’t know where these essential habitats occur or how they overlap with the open access fisheries that target sharks. Our study in Trinidad’s nearshore waters uses a 1km long, 100 hook longline to identify hotspots for elasmobranchs with particular focus on threatened hammerheads. To date, we caught 84 sharks and 27 rays across 13 species. Eight of these species are considered globally threatened by the IUCN and included the critically endangered Sphyrna lewini(4), Sphyrna tudes(8), and Fontitrygon geijskesi(1). Over 70% of our elasmobranch catch occurred on the east coast including all but one of the hammerheads. We are also performing monthly surveys of sharks at landing sites and fish markets around the island and collecting tissue samples for genomic analysis of the hammerheads. At these sites, we encountered over 630 sharks within 17 species, twelve that are threatened globally. Of the over 380 Sphyrna lewini surveyed, one was a mature male and all the females were <150cm indicating the catch consists of nearly all juveniles and Trinidad’s waters likely support important nurseries. Genomic analyses currently underway will enhance our understanding of the population and help identify areas for management.


    5.  11:00  Environmental Drivers of Batoid Distribution and Abundance in Long-term Fishery Independent Surveys in the Southeastern United States. Robin Minch*, University of Charleston, South Carolina; Tracey Smart, South Carolina Department of Natural Resources   minchre@g.cofc.edu

    Understanding the link between environmental conditions and the abundances and distributions of species is necessary to predict the future condition of marine resources under climate change. Rays have wide ranges of physiological tolerance, and their responses to changing conditions must be analyzed to understand the current and future state of our marine resources. From 1990 to 2019, the Southeast Area Monitoring and Assessment Program – South Atlantic (SEAMAP-SA) Coastal Trawl Survey, North Carolina Pamlico Sound Survey, and South Carolina Department of Natural Resources Trammel Net Survey captured ray species off the southeastern coast and in estuarine regions of the United States. The abundance and distribution of nine species were modeled using a vector-autoregressive spatio-temporal model (VAST) to create single and multispecies models including environmental parameters. Hypanus americanus and Hypanus sabinus significantly increased in abundance during the time series, increasing pressure on prey species. Gymnura micrura, Hypanus say, and Myliobatis freminvillei commonly cooccurred and exhibited a fluctuating abundance correlated with salinity. Aetobatus narinari moved significantly north, with more individuals observed beyond Florida over time. Gymnura micruraand Rhinoptera bonasus exhibited northward distribution shifts due to northern abundance increasing faster than southern regions. No species analyzed moved south. Bottom temperature was an important parameter in all models, with preferred temperatures varying between species. The abundances and distributions of ray species have changed over the last 30 years and will continue changing as environmental conditions become increasingly variable across the southeast, with repercussions for both humans and marine ecosystems.


    6.  11:15  A 10 year aerial survey of seasonal abundance and spatial distribution of blacktip sharks in Southeast Florida. Stephen Kajiura*, Florida Atlantic University; Jordan Waldron, University of North Florida   kajiura@fau.edu

    For the past 10 years (2011-2020) we have flown an aerial survey along the shoreline of southeast Florida to quantify seasonal abundance of blacktip sharks, Carcharhinus limbatus. A video camera recorded a field of view from the shoreline to approximately 200m offshore along a transect from Boca Raton Inlet to Jupiter Inlet (2011-2014) or Government Cut Miami to Jupiter Inlet (2015-2020). Blacktip sharks overwinter in southeast Florida from about January to April with a peak in abundance during February. Mean water temperature during those months has increased significantly over the past decade while mean shark abundance has declined. Peak shark abundance between Boca Raton Inlet and Jupiter Inlet exceeded 12,000 sharks in 2011, but did not exceed 3,000 sharks in 2020. Shark density differed significantly along the transect with the greatest density of sharks occurring in the northernmost sections. For the first four years of the study (2011-2014) sharks were found in the greatest density between Boynton Beach Inlet and Palm Beach Inlet. In subsequent years (2015-2020) the greatest density occurred farther north, between Palm Beach Inlet and Jupiter Inlet. This suggests a slightly more northern recent distribution. As global water temperatures continue to rise, sharks will likely be found at increasingly higher latitudes to remain within their preferred temperature range. Departure of sharks from their overwintering grounds was strongly correlated with increasing photoperiod, which, along with rising water temperature, might act as a cue to initiate northward migration.


    7.  11:30  Presence and distribution of two migratory shark species in an extreme tidal environment. Charles Bangley*, Dalhousie University; Dan Hasselman, Fundy Ocean Research Centre for Energy; Joanna Mills Flemming, Dalhousie University; Frederick Whoriskey, Ocean Tracking Network; Gregory Skomal, Massachusetts Division of Marine Fisheries; Megan Winton, Atlantic White Shark Conservancy; Bryan Franks, Jacksonville University; Chris Fischer, OCEARCH   charles.bangley@dal.ca

    Minas Passage, Nova Scotia sits in the upper Bay of Fundy and is the only access to Minas Basin for marine fishes. It is also home to the most extreme tides in the world, with a tide range up to 16 m and current speeds exceeding 5 m/s. The viability of tidal power extraction in Minas Passage is an area of active investigation. Here we describe patterns of presence and distribution for two migratory shark species, the spiny dogfish (Squalus acanthias) and white shark (Carcharodon carcharias), using acoustic telemetry and boosted regression tree-based species distribution modeling. Six spiny dogfish tagged in 2009 were detected in Minas Passage from 2010-2013, showing peaks in detection during June and November. A further 15 were tagged in September 2021 and a majority were still being detected that December. Fifteen white sharks originally tagged in the vicinity of Cape Cod, Massachusetts and other locations in the Northwest Atlantic were detected in the passage June-October from 2016 to present. Individuals of both species were detected in Minas Basin over multiple years and made repeated visits each year. BRT modeling assessed the influence of temperature, tidal current speed, and other hydrodynamic and environmental conditions on the spatial distribution of both species over the course of the full tidal cycle. This information will be critical in assessing the probability of encounter between migratory sharks and tidal power development, fisheries, and other human activities in Minas Basin.


    8.  11:45  Vertical and Diel Patterns of Adult Lemon Sharks (Negaprion brevirostris) around the Southeastern Florida and Western Bahamas Coastal Shelves. Jacquelyne Reuder*, Nova Southeastern University; Steven Kessel, John G. Shedd Aquarium; David Kerstetter, Nova Southeastern University   jr2863@mynsu.nova.edu

    The lemon shark (Negaprion brevirostris) is a large tropical species found in the western Atlantic Ocean from Virginia to Brazil, including the Bahamas and Caribbean Sea. Previous studies on habitat utilization were conducted on juveniles in the Bahamas, but little is known about vertical depth and temperature preferences of adults. Given the species’ risk to overexploitation and habitat degradation, the IUCN Red List recently listed lemon sharks as Vulnerable. Pop-up satellite archival tags (PSATs) were deployed on lemon sharks (n=7) in 2008 and 2009 off Jupiter, Florida and Tiger Beach, Bahamas for programmed periods ranging from 10 days to 120 days. Two of the PSAT-tagged sharks were also fitted with acoustic tags associated with the Florida Atlantic Coast Telemetry (FACT) Network array. Three females, two in Jupiter and one at Tiger Beach, show similar day and night patterns across the deployment period with distinctive dives at night which a GAM model suggests may be a 24-hr cyclical pattern. Additionally, this pattern is shown on different coastal shelves, the Florida and western Bahama shelf. A fourth PSAT was attached to an individual in Jupiter, which then crossed the Gulf Stream, and the tag detached near Tiger Beach, Bahamas – only the second known case of a lemon shark crossing the Gulf Stream. The four sharks showed the same temperature preference (22-24°C) except for the individual tagged in Tiger Beach which preferred warmer waters (25-27°C). Additional information on lemon shark habitat utilization will enable further bycatch reduction strategies for sustainable management.




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