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    V: Lightning Talks, Ichthyology

    2021-07-23   11:45 - 12:05

    Moderator: David Lonzarich

    2.  11:50  VIRTUAL    Comparative Morphology of Peripheral Hearing Structures in Three Species of Invasive Carps. Benjamin Colbert*, University of Maryland Center for Environmental Science, Chesapeake Biological Laboratory; Tanja Schulz-Mirbach, Ludwig-Maximilians University Munich; Brian Metscher, University of Vienna

    Silver carp (Hypophthalmichthys molitrix), a fish invasive to the United States, display a well-documented jumping response to the sound emitted by vessels or playbacks of vessel sound. Even though other closely related invasive carps have been shown to possess similar hearing abilities, only silver carp seems to respond in this characteristic way to sound. Resource managers are attempting various mechanisms to try and prevent the spread of invasive carps, including sound. However, before applying auditory deterrents to manage invasive carps, managers need a more thorough understanding of the hearing abilities, and especially if and to what degree these species differ in their peripheral auditory structures. We therefore set out to characterize and to compare the morphology of the inner ears, the Weberian apparatus, and the anterior chamber of the swim bladder (camera aerea Weberiana) in three carp species: silver carp, bighead carp (Hypophthalmichthys nobilis), and grass carp (Ctenopharyngodon idella). We applied a multiple- imaging approach using, among others, classical clearing-and-staining techniques to investigate bone and cartilage as well as contrast-enhanced µCT imaging to study the relationship between hard structures (e.g. otoliths, Weberian ossicles) and the surrounding soft tissue (e.g., interossicular ligaments). We will present these initial results and describe whether any difference in the anatomical structure of peripheral hearing structures may explain the different behavioral responses to sound.

    3.  11:55  VIRTUAL    New Insights Into the Morphology and Development of Novel Jaw-like and Tooth-like Structures in Male Deep-Sea Anglerfishes (Teleostei, Ceratioidei). Samuel Ghods*, University of Washington; Luke Tornabene, University of Washington; Karly Cohen, University of Washington, Friday Harbor Laboratories

    The deep-sea anglerfishes of the suborder Ceratioidei comprise one of the most morphologically unique groups of fishes in the world. Male ceratioids are dwarfed in comparison to the females, where females can be 60 times as long and nearly half a million times as heavy as the fully matured males. In place of the well-known lure seen in females, these dwarfed males are usually equipped with large nostrils and eyes as well as a specialized set of bones on the snout called the denticular apparatus. This apparatus consists of heavily toothed upper and lower denticular bones that are not present in the larval fish but grow as the fish matures, ultimately fusing together with the premaxilla and dentary, respectively. This study describes the origin and development of these denticular bones and teeth in the genus Melanocetus through an ontogenetic series of cleared and stained specimens and histological examination of the constituent parts. We also examine the differences between the teeth and dermal spinules seen in both the males and females to discuss any homologous elements or further evidence of sexual dimorphism. Finally, we compare males of two additional genera (Himantolophusand Linophryne) to discuss the morphological variation seen in this group as it relates to their highly specialized reproductive modes. These findings describe what may be an entirely unique jaw-like structure seen nowhere else in fishes and highlight the specialized anatomy of the often-overlooked male anglerfish.

    4.  12:00  VIRTUAL    Using fisher-contributed secondary fins to fill critical shark-fisheries data gaps. Jessica Quinlan*, Florida International University; Shannon O'Leary, Texas A & M; Andrew Fields, Texas A & M; Martin Benavides, University of North Carolina at Chapel Hill; Emily Stumpf, American Museum of Natural History; Ramon Carcamo, Belize Fisheries Dept; Joel Cruz, Belize Fisheries Dept; Derrick Lewis, Belize Fisheries Dept; Beverly Wade, Belize Fisheries Dept; George Amato, American Museum of Natural History

    Developing-world shark fisheries are typically not assessed or actively managed for sustainability; one fundamental obstacle is the lack of species and size-composition catch data. We tested and implemented a new and potentially widely applicable approach for collecting these data: mandatory submission of low-value secondary fins (anal fins) from landed sharks by fishers and use of the fins to reconstruct catch species and size. Visual and low-cost genetic identification were used to determine species composition, and linear regression was applied to total length and anal fin base length for catch-size reconstruction. We tested the feasibility of this approach in Belize, first in a local proof-of-concept study and then scaling it up to the national level for the 2017–2018 shark-fishing season (1,786 fins analyzed). Sixteen species occurred in this fishery. The most common were the Caribbean reef (Carcharhinus perezi), blacktip (C. limbatus), sharpnose (Atlantic [Rhizoprionodon terraenovae] and Caribbean [R. porosus] considered as a group), and bonnethead (Sphyrna cf. tiburo). Sharpnose and bonnethead sharks were landed primarily above size at maturity, whereas Caribbean reef and blacktip sharks were primarily landed below size at maturity. Our approach proved effective in obtaining critical data for managing the shark fishery, and we suggest the tools developed as part of this program could be exported to other nations in this region and applied almost immediately if there were means to communicate with fishers and incentivize them to provide anal fins.

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