The Gulf red snapper (Lutjanus campechanus) is a highly
exploited marine fish found primarily along the continental
shelf of the Gulf of Mexico (Hoese and Moore
1977; Allen 1985) and subjected to both recreational and
commercial fishing (Goodyear and Phares 1990). Red
snapper abundance in the northern Gulf of Mexico
(Gulf) has decreased by almost 90% since the 1970s
(Goodyear and Phares 1990), leading to intensive management
beginning in the early 1990s (Christman 1997).
A central question regarding conservation and management
of red snapper resources in the northern Gulf is
whether multiple management units (stocks) exist within
the fishery. The question is of importance because separate
management of regional stocks, should they exist,
is necessary to avoid regional over-exploitation and
maintain potentially adaptive genetic variation (Carvalho
and Hauser 1995; Hauser and Ward 1998).