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    V: Ichthyology VIII

    2021-07-26   13:30 - 15:30

    Moderator: Tracey Sutton

    1.  13:30  VIRTUAL    Cephalic and opercular morphology of the Anguilliformes (Teleostei: Elopomorpha). Vinicius Espindola*, Smithsonian National Museum of Natural History; David Johnson, Smithsonian National Museum of Natural History

    Anguilliformes are a group of teleost fishes with more than 1,032 described species in 20 families, commonly known as eels, congers, morays, and gulper eels. Comprehensive studies of Anguilliformes have not been completed, resulting in a lack of consensus for phylogenetic hypotheses. A detailed morphological analysis of the cephalic myology offers a promising new source of characters to understand the intrarelationships of Anguilliformes. Our study is the most extensive morphological analysis for the group to date and includes 103 terminal taxa, with representatives from each of the 19 families of Anguilliformes plus outgroup clades. Our results demonstrate that muscle characters inform phylogenetic relationships within Anguilliformes. We clarify several homology problems, such as the absence of the palatine in eels, opercle fused to the hyomandibular in Saccopharyngoidei (vs. articulating in remaining groups), and a new section of the levator operculi muscle (= depressor muscles, sensu Bertin) identified in snipe, gulper and one-jaw eels. We suggest three putative synapomorphies for Anguilliformes based on the adductor mandibulae origin, insertion, and sections. Moreover, uniquely among anguilliforms the levator operculi inserts on the medial rather than the lateral surface of the opercle in Protanguilla. Our conclusion supports previous analyses that indicate a basal position for Protanguilla as the sister group of the remaining members of the order.

    2.  13:45  VIRTUAL    Diversity of the Pectoral Girdle and Associated Morphology in Ricefishes (Teleostei: Beloniformes: Adrianichthyidae). Daniel Lumbantobing*, Smithsonian National Museum of Natural History; Lynne Parenti, Smithsonian National Museum of Natural History

    As part of a comparative morphological study of the ricefishes (family Adrianichthyidae) and their atherinomorph relatives (halfbeaks, killifishes, and rainbowfishes), we investigated the variation of the pectoral girdle and its associated structures—including the osteology and myology of some skull and vertebral elements. Three newly described or clarified characters support monophyly of the ricefishes are the absence of: (1) the mid-ventral spine of the posttemporal; (2) a ligament that connects the exoccipital and the posttemporal; and (3) the supracleithrum. Several osteological characters vary among subgroups of ricefishes and proposed character states may serve as their putative synapomorphies: (1) the relative distance between the pectoral girdle and the back of the skull; (2) the posterior cartilaginous extension of the exoccipital; (3) the shape and orientation of the posttemporal; (4) the shape of the dorsal ramus of the cleithrum; (5) the extension of the midproximal flange of the pectoral girdle; (6) the shape of the anteroventral margin of the cleithrum; and (7) the anteroventral extension of the coracoid connected to the cleithrum. Two myological characters somewhat associated with the pectoral girdle may diagnose some ricefish subgroups in Sulawesi, Indonesia: (1) the anterodorsal extension of the epaxial muscle that roofs the back of the skull; and (2) the anteroventral extension of the hypaxial muscle ventrally that covers the ventral portion of the pectoral girdle. We present a revised morphological diagnosis of the family Adrianichthyidae and some of its subgroups.

    3.  14:00  VIRTUAL    Cranial Lateral Line System and External Taste Buds in the Silverjaw Minnow, Ericymba buccata: Multimodal Contributions to Foraging Behavior? Aubree Jones*, University of Rhode Island; Kevin Conway, Texas A&M University; Jacqueline Webb, University of Rhode Island

    The cranial mechanosensory lateral line system (LL) of bony fishes is defined by five LL canal phenotypes as well as the presence of superficial neuromasts, whose distributions are not well studied. The LL canal system of the silverjaw minnow, Ericymba buccata, which feeds on invertebrates in sandy substrates, is unusual among fishes in that it demonstrates regional specialization, with narrow supraorbital canals on the dorsal surface of the head and widened infraorbital and mandibular canals ventral to the eye and on the lower jaw. Here we provide the first detailed description of the widened and narrow cranial LL canals as well as both canal neuromasts and superficial neuromasts using multiple morphological methods - histology, µCT, SEM, clearing and staining, and fluorescent vital staining. In adults, the canal neuromasts in the widened canals are ~3x the width of those in the narrow canals, but both have an elongated oval shape (like those reported in zebrafish, another minnow). In addition, >300 superficial neuromasts (on one side of the head) were found to be comingled with many small external taste buds in the skin overlying the widened infraorbital and mandibular canals. Regional specialization of the LL canals and comingling of the receptors of the mechanosensory and gustatory systems on the skin suggests that both sensory modalities contribute to benthic prey detection and assessment of food quality. Funded by ASIH Raney Award and NSF GRFP (AEJ), TAMU Agrilife Research (KWC) and George and Barbara Young Chair in Biology (JFW).

    4.  14:15  VIRTUAL    CANCELLED - Field Metabolic Rate and Prey Consumption Rate of Greenland Sharks (Somniosus microcephalus) Modeled Using Archival Biologgers. Eric Ste-Marie*, Department of Integrative Biology, University of Windsor; Yuuki Watanabe, National Institute of Polar Research; Jayson Semmens, Fisheries and Aquaculture Centre, Institute for Marine and Antarctic Studies, University of Tasmania; Marianne Marcoux, Arctic and Aquatic Research Division, Fisheries and Oceans Canada; Nigel Hussey, Department of Integrative Biology, University of Windsor

    5.  14:30  VIRTUAL    The Physiological Stress Response of Juvenile Nurse Sharks (Ginglymostoma cirratum) to Catch-and-Release Recreational Angling. Katherine Giesy*, University of Miami - Rosenstiel School of Marine and Atmospheric Science; Jake Jerome, University of Miami - Rosenstiel School of Marine and Atmospheric Science; Julia Wester, University of Miami - Rosenstiel School of Marine and Atmospheric Science; Danielle McDonald, University of Miami - Rosenstiel School of Marine and Atmospheric Science; Evan D'Alessandro, University of Miami - Rosenstiel School of Marine and Atmospheric Science; Catherine Macdonald, University of Miami - Rosenstiel School of Marine and Atmospheric Science

    Nurse sharks, (Ginglymostoma cirratum), especially juveniles, are often encountered by shore-based recreational fishers and released alive, with unknown physiological effects. Nurse sharks are suggested to exhibit minimal behavioral and physiological responses to capture, largely based on studies of adults using commercial or scientific fishing methods. In this study, 27 individuals (across 31 angling events) were caught using hook and line fishing methods. Over a 30-min period, 4 blood samples were taken with variable time intervals between sampling. Lactate was found to be significantly affected by blood draw number, fight time, and temperature. Significant relationships were also detected between blood draw number and glucose and hematocrit, while osmolality was only affected by fishing site. These results suggest juvenile nurse sharks exhibit a greater physiological stress response when exposed to recreational angling than adults captured with other fishing methods. In addition, this work was meant to validate the use of field POC devices designed for human blood in collecting physiological data from nurse sharks by comparing meter readings to values from laboratory assays. Results revealed the Lactate Pro meter predictably overestimated lactate concentrations and that differences can be compensated for by using an adjustment curve. Conversely, only a weak relationship was found between the Accu-Chek glucose meter and laboratory values, suggesting the machine may not be reliable for measuring glucose values in nurse sharks. While more research is needed to determine the impacts of capture stress on juvenile nurse sharks, these results highlight the potential for greater vulnerability in juvenile elasmobranchs.

    6.  14:45  VIRTUAL    Gill Slits Provide a Window into the Respiratory Physiology of Sharks. Wade VanderWright*, Simon Fraser University; Jennifer Bigman, Simon Fraser University; Cayley Elcombe, Simon Fraser University; Nicholas Dulvy, Simon Fraser University

    Metabolically important traits, such as gill surface area and metabolic rate, underpin life histories, population dynamics and extinction risk, as they govern the availability of energy for growth, survival and reproduction. Estimating both gill surface area and metabolic rate can be challenging, especially when working with large-bodied, threatened species. Ideally, these traits, and respiratory physiology in general, could be inferred from external morphology using a faster, non-lethal method. Gill slit height is quick to measure on live organisms and is anatomically connected to the gill arch. Here, we relate gill slit height and gill surface area for five Carcharhiniform sharks. We compared both total and parabranchial gill surface area to mean and individual gill slit height in physical specimens. We also compared empirical measurements of relative gill slit height (i.e. in proportion to total length) to those estimated from field guide illustrations to examine the potential of using anatomical drawings to measure gill slit height. We find strong positive relationships between gill slit height and gill surface area at two scales: (i) for total gill surface area and mean gill slit height across species and (ii) for parabranchial gill surface area and individual gill slit height within and across species. We also find that gill slit height is a consistent proportion of the fork length of physical specimens. Consequently, relative gill slit height measured from field guide illustrations proved to be surprisingly comparable to those measured from physical specimens.

    7.  15:00  VIRTUAL    Integrating physiology into population ecology: parallels between metabolic rates and population growth rates in fishes. Sarah Gravel*, Simon Fraser University; Jennifer Bigman, Simon Fraser University; Sebastian Pardo, Ecology Action Centre; Serena Wong, Pacific Salmon Commission; Nicholas Dulvy, Simon Fraser University

    The intrinsic rate of population increase is a fundamental parameter in fisheries management and conservation, representing a population’s capacity to replace itself. While we have long known that body size is a key correlate of population growth rate, there is increasing evidence that population growth rates vary latitudinally with temperature within and across species, suggesting there is a metabolic basis of population dynamics. Before asking questions, we highlight limitations in previous approaches to studying metabolic correlates in fishes: (A) experimental studies measure effects of oxygen upon metabolic rate, but are intraspecific and ignore body size, and (B) comparative cross-species analyses, which only consider body size and temperature effects on metabolic rate but not oxygen. We bridge across both approaches with a comparative analysis of population growth and metabolic rate, with oxygen, temperature, and body size. Specifically, we ask whether: (1) variation in metabolic rates can be explained by oxygen, temperature, and body size, (2) variation in population growth rates can be explained by oxygen, temperature, and body size, (3) differences in metabolic rate between elasmobranchs and teleosts underlie differences in population growth rate? From the primary literature, we datamined laboratory metabolic rate estimates and geographically matched them to population-specific trait data for 28 elasmobranch and 45 teleost fishes. We evaluated support for each hypothesis using the ‘ecological detective’ approach of model building and selection. This work will greatly inform our understanding of the biogeographical and physiological dimensions of population growth rates in the ocean.

    8.  15:15  VIRTUAL    Wedgefish and Guitarfish fisheries of India: addressing sustainability, livelihoods and conservation. Purushottama G. B.*, ICAR-Central Marine Fisheries Research Institute; Muktha, M., ICAR-Central Marine Fisheries Research Institute; Akhilesh, K. V., ICAR-Central Marine Fisheries Research Institute; Swatipriyanka Sen Dash, ICAR-Central Marine Fisheries Research Institute; Remya, L., ICAR-Central Marine Fisheries Research Institute; Shikha Rahangdale, ICAR-Central Marine Fisheries Research Institute; Livi Wilson, ICAR-Central Marine Fisheries Research Institute; Mahesh, V., ICAR-Central Marine Fisheries Research Institute; Ambarish P. Gop, ICAR-Central Marine Fisheries Research Institute; Subal Kumar Roul, ICAR-Central Marine Fisheries Research Institute

    Wedgefishes and guitarfishes (W&GF) are one of the most vulnerable groups being fished globally but are one of the least studied groups as well. In India, W&GF landingsincreased marginally from an annual average of 2,364 t (1985–1994) to 2,874 t (2011–2020). Trawls landed ~73% of W&GF, followed by gillnets (~17%), artisanal gears (~5%) and hook & lines (~3%). Though W&GF formed only 0.1% of total marine landings in India, these species are ecologically important in coastal waters. Twelve species belonging to the families Rhinidae, Rhinobatidae and Glaucostegidae are landed in India, with Rhynchobatus laevis& Rhinobatus annandaleibeing dominant along the west coast and Rhinobatos lionotus&Glaucostegus granulatus,along the east coast. Seasonality in the landings of W&GF was observed and the west coast contributed significantly to W&GF landings (64%).Evidence of population decline of W&GF species has been voiced by stakeholder communities. Varying abundance in bycatch landings and minimal numbers in commercial landings makes the conservation of this group highly challenging. This study capsules historic trends and current status of W&GF landings in India and identifies research gaps in understanding the biology, ecology and diversity of W&GF in Indian waters, vital to sustain their fisheries and population in the region.

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