Restoration of Gulf Striped Bass: Lessons and Management Implications
Eric A. Long, Charles L. Mesing, Karen J. Herrington, Robert R. Weller, and Isaac I. Wirgin
Abstract.—Since the 1970s, the only known naturally reproducing population of native Gulf of Mexico (Gulf ) striped bass Morone saxatilis occurs in the Apalachicola–Chattahoochee–Flint River system (ACF) in Florida, Georgia, and Alabama.To augment its depleted population, low numbers of fry and fingerlings of Atlantic coast ancestry were released into the ACF between 1965 and 1976.Restoration of Gulf striped bass was initiated in 1980 when putative Gulf fingerlings spawned from Apalachicola River (Gulf ) broodfish were stocked back into the ACF. Since the initial stocking, approximately 10 million phase-I (25–50 mm) and 900,000 phase-II (150–250 mm) fingerlings have been released into Lake Seminole and the Apalachicola River, with hundreds of thousands more released into upstream reservoirs. Low levels of successful natural reproduction in the ACF were documented in 9 of the 10 years that natural reproduction was evaluated. Marked stocked fish have typically comprised 75–100% of fall age-0 samples. After stocking was initiated, striped bass harvest estimates increased as much as 10-fold during peak-season creel surveys conducted in the tailrace of Jim Woodruff Lock and Dam. A comparison of Atlantic-origin and Gulf striped bass co-stocked into an adjacent river-reservoir system over a 5-year period indicated no consistent differences in relative survival or growth through age 4. Gulf striped bass occupied coolwater thermal refuges during summer. Enhancement of thermal refuge habitats was successful, but results were short-lived. Small populations of Gulf striped bass, dependent on stocking of hatchery fish, now exist in several Gulf of Mexico tributary systems where adequate habitat is present.Genetic analysis of both mitochondrial and nuclear genomes revealed that a high percentage of fish from the ACF exhibit mitochondrial DNA (mtDNA) haplotypes and nuclear DNA (nDNA) alleles that are absent in Atlantic populations.However, significant introgression of Atlantic nDNA alleles was documented in the extant population. Knowledge of the life history of Gulf striped bass was improved as a result of this multi-state collaboration as well as a large stocking program, new Gulf broodfish repositories, extensive genetic cataloged database,and expanded trophy fisheries. ACF Gulf striped bass restoration goals and objectives were defined, adjusted, and revised throughout the collaborative process to meet the concerns and management needs of all participating agencies.