Maturation, Fecundity, and Spawning Frequency of the Albemarle/Roanoke Striped Bass Stock

Abstract

The principal striped bass, Morone saxatilis population in North Carolina, the Albemarle/Roanoke (A/R) stock has grown tremendously in size and age structure over the last twenty years necessitating an up-to-date maturity and fecundity schedule. The last study was conducted for the Albemarle Striped Bass Management Board in 1989-1990 by Olsen and Rulifson (1992) after the stock had crashed, and just before stock rebuilding took place. There have been many advances in the understanding of teleost reproduction since their study and in recent years, otolith microchemistry with concentrations of elements such as strontium (⁸⁸Sr) has been used to determine movement and migration of different species to delineate movement from freshwater to more saline environments. The objectives of this study were to complete a maturation and fecundity schedule, compare results to Olsen and Rulifson (1992), and test the use of ⁸⁸Sr to elucidate migration patterns. Samples were collected (n=453) in 2009 and 2010 on the Roanoke River near the spawning grounds and in Albemarle Sound during the pre-spawn, spawning, and post-spawn periods (March through May) with total lengths (TL) ranging from 300 to 1,080 mm corresponding to age-3 to age-16. Striped bass are total spawners with determinate fecundity maturing one clutch or group of oocytes each year and having primary growth oocytes (PG) at each stage of development. Female striped bass were 96.8% mature by age-4 with fecundity ranging from 176,873 eggs (age-3) to 3,163,130 eggs (age-16). These findings are different from Olsen and Rulifson (1992) who reported 92.9% mature by age-4 with 43.8% overall greater fecundity estimates attributed to the sample size and methodologies. Otoliths were examined using Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) to determine changes in concentrations of the element ⁸⁸Sr over the life of the fish that reflect high salinity or freshwater environments and fish were assigned residency (77.4%) or anadromy (22.6%). It is recommended that management agencies continue to consider age-4 female striped bass the first year class to contribute to the spawning population in the A/R stock and to keep the minimum size limit of 18 in in place; however, adjusting the slot limit of 22-27 in would be beneficial to fishermen without decreasing the spawning stock. It is recommended to continually monitor the reproductive rates of the population to ensure the health of the stock.