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|Presentation Title||Hickory Shad Otolith Development as Viewed using Scanning Electron Microscopy|
|Presenting Author Name||Roger Rulifson|
|Presenting Author Affiliation||East Carolina University|
|Unit Meeting||Tidewater Chapter|
|General Topic||otolith development|
|Type of Presentation||Oral|
The Hickory Shad, Alosa mediocris, is an anadromous clupeid with spawning populations between the Susquehanna River, Maryland, and the St. John’s River, Florida. To our knowledge, this is the first series of microphotographs of the species using scanning electron microscopy (SEM). Earliest otoliths from a specimen 57 mm TL show few features on the distal side and developing features on the proximal (sulcus) side. Adult otoliths exhibit 11-15 invaginations along the distal ventral edge, often with holes in the calcium matrix midway toward the otolith core. We believe the otolith nucleus contains a magnesium crystal, which may function as the “seed” for otolith formation. Unlike the other Alosines, the end of the antirostrum appears more or less as a rectangle and is not contiguous with the main otolith body. Often the postrostrum possesses an extension, or spur, which can be short or long. The appearance of the spur in the sampled spawning population is significantly related to latitude of the spawning watershed. The function of the spur is unknown at this time.