Prior genetic studies on adult red snapper sampled
across the northern Gulf have generally revealed
homogeneity among localities, consistent with the existence
of a single stock (Camper et al. 1993; Gold et al.
1997; 2001; Garber et al. 2004; but see Bortone and
Chapman 1995). The genetic data, however, are not fully
consistent with studies of post-juvenile life history and
with most tag-and-recapture experiments that indicate
adult red snapper are sedentary and exhibit high site
fidelity (Fable 1980; Szedlmayer and Shipp 1994;
Szedlmayer 1997; but see Patterson et al. 2001). Two
hypotheses forwarded to account for these seemingly
disparate observations are (1) gene flow, perhaps
occurring from hydrodynamic transport of pelagic eggs
and larvae across the northern Gulf (Goodyear 1995), is
sufficient to preclude genetic divergence, or (2) gene flow
across the northern Gulf is limited but there has been
insufficient time for semi-isolated lineages to completely
sort into monophyletic assemblages (Gold and Richardson
1998; Gold et al. 2001). A third hypothesis is (3)
that gene flow/isolation among assemblages or lineagesof Gulf red snapper is a dynamic process that varies in
intensity and duration through both time and space.
Under this hypothesis, gene flow over the short term
could be fairly restricted geographically, while over the
long term be more extensive and largely a function of
passive and more-or-less random (in terms of strength
and duration) movement of individuals at one of any
life-history stages. Different assemblages (stocks) might
thus arise in the short term but appear homogeneous
over the long term.