Movements of North Carolina Striped Bass, Morone saxatilis, Inferred through Otolith Microchemistry

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Zurlo, Daniel J.

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East Carolina University


Striped Bass, Morone saxatilis, is an anadromous, recreationally and commercially important fish species found throughout the U.S. Atlantic east coast, whose migrations have been intensely studied. A review of the relevant literature on Striped Bass migrations revealed that the paradigm of Striped Bass migration along the U.S. Atlantic coast should be updated, as new information has shown that in addition to the Chesapeake Bay and Hudson River, the Roanoke River, NC, Delaware River, and possibly the Shubenacadie River, Nova Scotia, Canada, may also contribute fish to the mixed Atlantic Migratory Stock. The needs for an updated delineation of stocks that contribute to the Atlantic Migratory Stock and determination of inshore migrations and habitat use were identified as additional avenues for further research. In effort to answer the latter question, the inshore movements and potential mixing of North Carolina stocks of adult Striped Bass from separate management areas (Albemarle Sound Management Area, ASMA, and Central Southern Management Area, CSMA) were determined using otolith microchemistry. Trace element ratios (strontium:calcium, Sr:Ca; barium:calcium, Ba:Ca; magnesium:calcium, Mg:Ca; and manganese:calcium, Mg:Ca) measured through inductively coupled plasma optical emission spectrometry (ICP-OES) from ASMA and CSMA water samples were used to determine that each management area had different water chemistries through linear discriminant function analysis (LDFA), allowing for discrimination of otolith chemistries of fish from different management areas. Adult otolith elemental concentrations of Sr, Ba, Mg, and Mn, measured using laser ablation inductively couple plasma mass spectroscopy, of fish from separate management areas were compared using linear discriminant function analysis, which determined that little mixing of adult fish occurred between the two management areas, except in years of high abundance of ASMA fish, in which those fish would migrate to the CSMA. The same methods were used on CSMA fish determined to be of hatchery or wild origin by Dobbs (2013) to determine that CSMA hatchery and wild fish use different habitat during their sub-adult and early adult lives, but similar habitat as they aged. Finally, otolith microchemistry was used in an attempt to determine if the Roanoke River, NC (ASMA) contributed fish to the Atlantic Migratory Stock, as North Carolina Division of Marine Fisheries (NCDMF) tag returns indicated the Roanoke River was contributing significant numbers of fish. Otolith Sr:Ca ratios were used to determine anadromous migrations, as otolith Sr:Ca is directly correlated to ambient salinity. Results did not agree well with NCDMF tagging, as many larger fish exhibited resident Sr:Ca profiles, whereas NCDMF tag returns indicated that most, larger (>800 mm total length, total length) fish were anadromous and undertook long distance migrations. It is possible that the Roanoke River harbors discrete resident and anadromous contingents of large, adult Striped Bass.