14 
Fishery Bulletin 116(1) 
Scatter plots of the relationship between incidental catch per unit of effort (in logarithmic scale) for each size 
class of dolphinfish (Coryphaena spp.) and (A) sea-surface temperature (SST), (B) chlorophyll-a concentration 
(chl-a), and (C) sea-surface height (SSH) in the eastern Pacific Ocean off Mexico during 2004-2013. Points in¬ 
dicate observed values, and the colored lines were generated by fitting the polynomial linear models to the data. 
7674 fish (38% of total fish in this class) were caught 
in waters with SSH from 0.05 to 0.1 m, and 5149 fish 
(25% of total fish in this class) for this size class were 
caught in SSH values from -0.05 to 0 m. Fish in the 
large-size class showed SSH preferences similar to 
those in the medium-size class, with 27% (7229 fish for 
this class) and 23% (6059 fish) of total fish caught in 
SSH ranges from -0.05 to 0 m and from 0.05 to 0.1 m, 
respectively (Fig. 5E). 
Figure 6 shows the spatial distribution of total esti¬ 
mated ICPUE and (A) mean SST, (B) chl-a concentra¬ 
tion, and (C) SSH values for the whole study area. 
In general, most dolphinfish catches occurred south 
of the 21°C isotherm, especially around the 25°C iso¬ 
therm, and few catches occurred in waters with SSTs 
over 28°C. The 10-year average SST values higher 
than 21°C and lower than 28°C occurred both in the 
oceanic zone and near the coast of the BCP, especially 
in the central portion of the study area, and in the Gulf 
of California. Values higher than 28°C occurred near 
the coast, south of 18°N and east of 110°W. 
The vast majority of dolphinfish ICPUE occurred, 
for the 10-year average, west of the 0.20 mg/m 3 isoline. 
This area with values of chl-a concentration lower than 
0.20 mg/m 3 represented most of the oceanic zone, with 
the exception of an area east of ~104°W. High (>1 mg/ 
m 3 ) values were found in coastal zones, especially in 
the upper Gulf of California, the west coast of the BCP, 
the Cabo Corrientes area (~21°N, 105°W), and the Gulf 
of Tehuantepec, in the southern portion of the study 
area. 
The 10-year average for SSH resulted in posi¬ 
tive values for the study area. Most dolphinfish were 
caught in or near the 0.02 m SSH isoline, which was 
located mainly in an oceanic area around 11-18°N and 
125-110°W. In the west coast of the BCP, high ICPUE 
occurred where SSH values were greater than 0.03 m. 
Analysis of high-catch quadrants and their relationship 
with the 25°C isotherm 
The lower limit of the upper quartile of the ICPUE 
vector was 42.62 fish/set; hence, all the quadrants 
with catches higher than this value were considered 
high-catch quadrants. Mean monthly latitude for these 
quadrants increased from January through August and 
then decreased from August to November, and no high 
catch quadrants were observed during December. The 
opposite was observed in the monthly mean longitude 
for these quadrants: a decrease from January to Au¬ 
gust and an increase from August to November (results 
not shown). When visualized in latitude and longitude 
