Contribution of Stocked American Shad Fry to Juvenile American Shad Outmigration in the Roanoke River, North Carolina

Significant declines in American shad (Alosa sapidissima) populations have warranted restoration efforts by natural resource agencies along the Atlantic coast. In 1998, the North Carolina Wildlife Resources Commission developed a restoration plan for declining stocks of American shad in the Roanoke River. One strategy in the plan was to supplement wild American shad reproduction with annual stockings of hatchery-reared American shad fry. The fry were marked with a discrete oxytetracycline (OTC) mark specific to the stocking year and stocking location in the upper Roanoke River basin. Total numbers of American shad fry stocked ranged from 481,000 in 1998 to 2.5 million in 2005. To evaluate the contribution of stocked American shad fry to the portion of juvenile American shad that outmigrate, we checked for OTC marks on processed otoliths of American shad juveniles collected at night during weekly fall (September-November) samples in the lower Roanoke River. From 2000 to 2005, using boat-mounted electrofishing gear, we collected and processed a total of 985 juvenile American shad with total lengths from 48 mm to 107 mm. Numbers of American shad juveniles collected ranged from 4 juvenile American shad in 2000 to 421 juvenile American shad in 2005. Since our first OTC-marked juvenile collected in 2002, the number of OTC-marked juvenile American shad, with total lengths ranging from 48 mm to 95 mm, comprised between 1% and 9% of the total juvenile American shad captured over the last four years. We present the annual contribution of hatchery-reared American shad to wild juvenile American shad abundance as well as a comparison of the relative contributions of two separate stocking locations. Ultimately, successful fry stockings yielding hatchery-reared juveniles may enhance the spawning stock of American shad on the Roanoke River.

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