NMFS NUMBER: 96-NER-086
Critical Evaluation of Conservation Success in Restoration
of James River and Ocean-Run American Shad
L. Brown, J. M. Epifanio, T. Gunter, J. G. Travelstead,
and J. M. Waters
Marine Fisheries Service, Northeast Region, One Blackburn
Drive, Gloucester, MA 01930. TELEPHONE: (978)
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:
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.
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
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.
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
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.