Critical Evaluation of Conservation Success in....
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GRANT NUMBER:  NA76FD0147           NMFS NUMBER:  96-NER-086

REPORT TITLE:  Critical Evaluation of Conservation Success in Restoration of James River and Ocean-Run American Shad

AUTHOR:  B. L. Brown, J. M. Epifanio, T. Gunter, J. G. Travelstead, and J. M. Waters

PUBLISH DATE: May 1, 2000

AVAILABLE FROM:  National Marine Fisheries Service, Northeast Region, One Blackburn Drive, Gloucester, MA 01930.  TELEPHONE:  (978) 281-9267


The investigators examined the efficiency of captive breeding and release for recovery of viable American shad populations in the James River, Virginia, watershed.  Responding to severe declines in the strength of the anadromous runs in the James and other East Coast rivers, state and federal agencies responsible for managing the resource deemed that a propagation program was necessary to help the James population to achieve long-term viability.  Our project was designed as a model to combine molecular genetic methods with other traditional marking approaches for evaluating the effects and contribution of the propagated fish to a recovered population.  The investigation focused on four key questions:

1.    Is there evidence of an infra-specific stock structure among river populations of American shad in the mid-Atlantic?  The purpose of this part of the study was to establish appropriate sources of brood from several candidate populations.  Ultimately, the investigators observed that, based on microsatellite DNA variation (and from mitochondrial DNA variation previously recorded for those specimens), temporally stable genetic character arrays differed among rivers without any observable fine-scale structure.

2.    Does the brood collection strategy capture the full range of genetic variation observed in the source population?  The investigators observed no significant differences between the allelic arrays of captured brood and the source-river population.

3.    Do hatchery-reared juvenile shad capture the full range of diversity in the source-river population?  We observed a comparable level of diversity in the progeny compared with the parents.

4.    Are there any temporal changes in the investigators' pool of molecular markers signaling a response to artificial selection for conditions in the culture environment?  In several experiments the investigators detected differences in the genetic arrays between family-sets taken early (post-fertilization) and late (pre-stocking) in the culture process.  These results are consistent with expectations from hatchery selection, although additional tests are required to confirm the importance of selection and to confidently eliminate other explanations such as possible sampling bias.

The results from the evaluation have resulted in several changes in the James River breeding and culture program to promote/mimic more natural background levels of genetic diversity as well as to ensure viable populations of American shad.

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