264 
Fishery Bulletin 95(2), 1997 
influence on the distribution of larval C. pauci- 
radiatus and other pelagic species. 
In conclusion, this study indicates that larval C. 
pauciradiatus are a frontal species, concentrated at 
temperature fronts throughout the Gulf of Mexico. 
This is an important concept that needs to be recog- 
nized. Fronts and eddies are fundamental to the 
world oceans, and they are the only coherent feature 
in the Gulf of Mexico. The Loop Current itself acts 
as a zoogeographic barrier separating the oceanic and 
shelf species (Richards et al., 1993). Although it is 
not surprising that certain species have evolved to 
take advantage of this environment, it means that 
frontal species must be recognized as such in order 
to sample and manage these stocks effectively. 
Spawning-stock biomass estimates are an impor- 
tant consideration in the management of pelagic spe- 
cies. These are inferred from the abundance of lar- 
vae taken at fixed stations (CalCofi, SEAMAP). If 
the target species is tied by life history parameters 
to a frontal system, then its apparent abundance will 
be affected by the extent of the frontal system found 
within the sampled area. For instance, if the frontal 
system within the area sampled is extensive, higher 
numbers of larvae are expected. Likewise, if only a 
small portion of the frontal system is sampled, then 
numbers are expected to be low, as was the case in 
1986. Thus, the lower abundance estimates do not 
necessarily mean that there were fewer fish spawned 
that year but, rather, may indicate that they were 
spawned along the front outside the area sampled. 
Accurate abundance estimates are a problem in 
the Gulf of Mexico because only the northern and 
eastern Gulf are sampled. The boundaries of the Loop 
Current pass through the Exclusive Economic Zone 
of the United States, Mexico, and Cuba, and the large 
anticyclonic rings often pass south of the area 
sampled. In addition, there is considerable variation 
in abundance along a temperature front. It is impor- 
tant to note that the presence of a frontal region in 
itself does not necessarily constitute a favorable habi- 
tat, but favorable spatial and temporal patterns of 
the front may determine the abundance of the lar- 
vae on a basin scale. 
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