Maturation and fecundity of the Neuse and Tar-Pamlico Rivers striped bass (morone saxatilis) stocks in coastal North Carolina

ECU Author/Contributor (non-ECU co-authors, if there are any, appear on document)

Evan Knight (Creator)

Institution

East Carolina University (ECU )

Web Site: http://www.ecu.edu/lib/

Abstract: The Albemarle/Roanoke stock makes up the largest contingent of Striped Bass (Morone saxatilis) in the state\; however, other economically important populations exist elsewhere. The Central Southern Management Area (CSMA) is one such region. Striped Bass populations are sustained in the CSMA through stocking by the North Carolina Wildlife Resources Commission (NCWRC), but the goal of the fishery management plan is to establish a self-sustaining spawning population of Striped Bass in the region. In order to improve management of the CSMA Striped Bass population, maturation and fecundity estimates are needed for stock assessment models. Striped Bass were sampled on and near the spawning grounds in the Neuse and Tar/Pamlico rivers during the pre-spawn, spawning, and post-spawn period (February-June). Each fish was measured (fork length and total length, mm) and weighed (g). Otoliths were removed for ageing and otolith chemistry. Sex was determined, and gonads were removed and weighed to determine the GSI and phase of reproduction. LSI and K factors were used to assess the condition of fish. Otoliths were sectioned for age, and then examined by LA-ICPMS to determine changes in concentrations of Strontium in the first year of life to determine origin. The age at 50% maturity was 2.67 years\; by Age 3 98.2% of female Striped Bass were sexually mature. CSMA Striped Bass matured 0.5 years earlier compared to the ASMA/RRMA population. Fecundity ranged from 223,110 eggs for an Age-3 female to 3,273,206 eggs for an Age-10 female (Mean=769,048.54\; SE=54,047.42\; n=87). Fish in the CSMA produced more eggs than ASMA/RRMA Striped Bass when compared by age. Observed lengths at age were significantly different between the CSMA and ASMA/RRMA females (F=978.92\; DF=1\; p<\;0.0001). Results of otolith microchemistry revealed that 92.7% of female Striped Bass in my study were of hatchery origin. Hatchery and wild fish did not vary significant by condition factors or age and growth\; however, oocyte characteristics did vary significantly by origin. Wild fish produced oocytes of higher mass and larger in diameter compared to hatchery fish. Length at 50% maturity in the CSMA was estimated at 467.8 mm TL (18.4 inches TL) and fish were estimated to be 100% mature at 537.3 mm TL (21.1 inches TL). The current harvest restrictions for Striped Bass are an 18-inch TL minimum. In order for fishery managers to ensure all fish have the opportunity to enter the spawning stock at least once before being harvested, minimum harvest restrictions should be set at 21 inches TL. Both wild and hatchery adults are capable of fully contributing to the spawning run, yet the stock is not recovering. Early life mortality investigations into why the stock is not recovering should be undertaken.

Additional Information

Publication

Thesis

Language: English

Date: 2023

Subjects

Aquatic sciences;Fecundity;Hatchery;Maturation;Morone saxatilis;Otolith chemistry

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