GRANT
NUMBER:
NA76FD0144
NMFS NUMBER: 96-NER-107
REPORT
TITLE:
Mixed-Stock Analysis of Wintertime Aggregations of Stripped
Bass along the Mid-Atlantic Coast
AUTHOR:
Isaac Wirgin and John Waldman
PUBLISH
DATE:
December
14, 1999
AVAILABLE
FROM:
National Marine Fisheries Service, Northeast Region, One
Blackburn Drive, Gloucester, MA 01930. TELEPHONE:
(978) 281-9267
ABSTRACT

Almost all
stripped bass (Morone saxatilis) along the mid-atlantic
coast originate from two estuaries: the Hudson River and
Chesapeake Bay. Both stocks winter in coastal waters,
where they may be subject to bycatch fisheries (e.g..,
the Cape Hatteras, North Carolina, dogfish fishery). Virtually
nothing is known regarding the stock composition of wintertime
aggregations of stripped bass. During the mid-1970's,
it was estimated that about 90% of the stripped bass found
along the northeast U.S. coast were from the Chesapeake
Bay; by the late 1980's the Hudson River was contributing
more than half of stripped bass found along the coast.
In 1993, the historical high for the Maryland juvenile
stripped bass survey was recorded; thus, relative contributions
of the two stocks may have shifted back toward domination
by the Chesapeake Bay stock. We analyzed genotypic frequency
data derived from composite information on single-copy
nuclear DNA and mitochondrial DNA major length variation
of stripped bass collected from three latitudinally-widespread
locations: during winter 1995-1996 off the New Jersey
coast, and during winter 1997-1998 at the mouth of Delaware
Bay and off Cape Hatteras, North Carolina. We also
determined genotypic frequencies for stripped bass from
three reference spawning tributaries of the Chesapeake
Bay not previously characterized, the Nanticoke, Patuxent,
and Pocomoke rivers. Contingency analysis indicated an
absence of statistical heterogeneity among the three wintertime
coastal collections. Stock composition analysis of the
aggregate wintertime collections (N=356) showed a strong
Chesapeake Bay contribution (80%) and a lower Hudson River
contribution (20%). Stock composition analysis of the
contemporaneous Delaware Bay and North Carolina collections
in aggregate, showed relative contributions of about 16%
for the Hudson River stock and 84% for the Chesapeake
Bay stock. Discrete stock composition analyses on the
three collections suggested a significantly higher Hudson
River contribution for the New Jersey collection, but
the asynchronicity and statistical questions render The
validity of such analyses as uncertain. We also examined
the utility of additional mitochondrial DNA and nuclear
DNA markers (microsatellites).