Lamkin: The Loop Current and abundance of larval Cubiceps pauciradiatus 
257 
umes were also at or near maxima at 
the same stations where C. pauci- 
radiatus were abundant. In the 1988 
transect, with stations 8 km apart, the 
patterns of abundance clearly showed 
that C. pauciradiatus prefer the fron- 
tal interface between the Gulf common 
water over the continental margin and 
the subtropical underwater of the Loop 
Current. Larvae were not present until 
the SST began to increase, rose to a 
peak after the initial temperature in- 
crease, then declined sharply in the 
warmer waters. Bulk plankton displace- 
ment volumes did not follow an identi- 
cal pattern but nonetheless peaked in 
mid-transect, just before those stations 
where C. pauciradiatus were most 
abundant. Such patterns may be a spa- 
tial consequence of the fact that this 
transect had stations 8 km apart rather 
than 3.2 km apart. 
Discussion 
In this study, the abundance and dis- 
tribution of larval C. pauciradiatus 
were examined over five yearly surveys 
and seven transects. Analyses of survey 
data and transects depict a species 
whose adult spawning grounds and lar- 
val habitat are tied to sharp tempera- 
ture gradients associated with the Loop 
Current in the eastern Gulf and to an- 
ticyclonic-cyclonic rings in the western 
Gulf of Mexico. Larval C. pauciradiatus 
were most abundant near a tempera- 
ture front. It is apparent from these 
data and the transects made in 1987 
and 1988 that this frontal environment 
is the preferred habitat and probable 
spawning area for the adult population 
of C. pauciradiatus in the Gulf of 
Mexico. Salenkov (1989) found that ar- 
eas of highest density of juvenile and 
adult C. pauciradiatus in the tropical 
Atlantic Ocean were situated in zones 
of high production such as the edge of 
cyclonic gyres, the equatorial countercurrent, and the 
upwelling regions of the Sierra Leone Ridge. 
In general, fish are often found aggregated at fronts 
(Brandt and Wadley, 1981; Nero et ah, 1990). Cur- 
rently there are two competing theories to explain 
this relationship: 1) that fish have thermal require- 
ments and are attracted to temperature gradients, 
and 2) that fish are attracted to fronts because of the 
increased concentration of prey (Brandt, 1993). A 
third explanation may be that spawning in a frontal 
area may also provide optimal conditions for survival 
and growth of larvae and that increased concentra- 
