Lamkin. The Loop Current and abundance of larval Cubiceps pauciradiatus 
253 
considerably from year to year and within years 
(cruises) in both the eastern and western Gulf of 
Mexico. A brief synopsis of the circulation patterns 
present throughout this study are presented below. 
Figure 1 shows the position of the 22° isotherms 
at 100 meters (Loop Current frontal edge) in the east- 
ern Gulf of Mexico for each of the 5 years covered in 
this study. In 1983, 1984, and 1988, the Loop Cur- 
rent extended north to 27°N. However, in 1986, the 
Loop barely penetrated into the sample area, and in 
1987, a broad front stretched from 88°W to 84°W, al- 
though not as far north as in other years. The posi- 
tions of the Loop Current and cyclonic-anticyclonic 
rings are detailed in Figures 2—11. 
Although Figure 1 indicates the position of the 
Loop current at the time of the survey, it does not 
reflect the dynamics of the system nor the formation 
of warm-core eddies. The northward penetration and 
stability of the Loop Current front is directly im- 
pacted by formation and separation of warm-core 
eddies. In 1983, a ring began to form in January but 
did not separate until March and left the Loop Cur- 
rent extended to the northeast with the northern 
boundary at 27°N (Fig. 2). It remained in that posi- 
tion throughout most of the spring. In contrast, the 
Loop Current underwent ring-shedding events in 
January 1984 and 1986, and the front remained far- 
ther south and with a much narrower frontal area 
(Figs. 3-5). In 1987, and 1988, ring formation had 
taken place in September-November of the previ- 
ous year. However, the Loop Current did not push 
north until the spring of the following year. 
The presence or absence of the anticyclonic (warm- 
core) rings and their companion cyclones (cold-core) 
also strongly influences the circulation in the west- 
ern Gulf of Mexico. Anticyclonic rings were present 
in the western Gulf of Mexico in all years, although 
their influence on the area sampled varied consider- 
ably. In 1983, 1984, and 1986, warm-core rings were 
present in the western Gulf. In 1987, and 1988, their 
influence was restricted to the southern part of the 
survey area, and in 1988, the temperature signature 
was evident only at 200 m. Cyclones were also 
present, although the number and position varied 
considerably from year to year. However, in some 
years it was not possible to resolve the circulation 
patterns because of difficulty in obtaining sufficient 
sample density. 
Distribution and abundance 
In each year of this study, larval C. pauciradiatus 
were most abundant in temperature gradients: in the 
Loop Current front between the the 22° and 20° iso- 
therms and in the gradients of 16-20°C associated 
with cold cyclonic rings. Abundance varied consider- 
ably from year to year and between 
the eastern and western Gulf. 
Overall, abundance was greatest 
in 1983 and lowest in 1987. In 
1983, C. pauciradiatus were 
present at 41 of 99 stations, with 
peak catches in the southeast of 
162 and 188 individuals under 10 
nr (Fig. 2). Thirty six of the 41 sta- 
tions were in the eastern Gulf. In 
succeeding years, abundance was 
greatly reduced. In 1984, C. pauci- 
radiatus were present at only 9 
stations in the eastern Gulf (Fig. 3). 
This pattern continued through 
1988, when C. pauciradiatus was 
found at no more than 9 stations and 
at as few as 4 (leg 2, 1988). Although 
C. pauciradiatus were present at a 
few stations inshore, most were 
found concentrated around the Loop 
Current, but not in its interior. 
Peak catches often occurred when 
a station coincided with a cyclonic 
meander at the Loop Current or in 
areas associated with cyclonic 
rings and cold water intrusions. 
-90 -89 -88 -87 -86 -85 -84 -83 -82 -81 
Figure 1 
Position of Loop Current (22°C at 100 m) for each year and leg. 
