Power and May: Sea-surface temperatures and Thunnus albacares catch and effort 



431 



TEXRS 



LOUISIANA 





CLOUDS 



f ,-fcv 



Figure 1 



Enhanced satellite sea-surface temperature image of the northern Gulf of Mexico acquired by the NOAA-9 satellite on 21 March 1988. 



of sets available for analysis was 6618. The median 

 longline length deployed was 24 miles, although some 

 sets were recorded as over 70 miles long. The median 

 number of hooks per set was 576, and the median 

 number of hooks per mile of set was 24. Yellowfin tuna 

 CPUE was computed by combining the number of fish 

 kept with the number discarded, and tabulating CPUE 

 as the total number of fish caught per 1000 hooks per 

 set. 



The satellite image database was developed from a 

 total of 109 Advanced Very High Resolution Radio- 

 meter (AVHRR) images of the Gulf of Mexico obtained 

 from archives maintained by the National Environmen- 

 tal Satellite Data Information Service (NESDIS) and 

 NMFS. The imagery was acquired by the NOAA-9 and 

 NOAA-10 satellites. In selecting images for analysis, 



an effort was made to exclude those containing signifi- 

 cant cloud cover. This selection was made either by 

 NMFS personnel while compiling their image archive, 

 or by us during examination of images in the NESDIS 

 archives. Although a total of ten images acquired 

 during August-September 1987 were obtained from 

 NMFS and included in the analysis, we did not obtain 

 additional summertime imagery for the study, since 

 SST in the Gulf is nearly isothermal during that time 

 of year (Huh et al. 1978; see also summer month 

 editions of the Oceanographic Monthly Summary). 

 Consequently, the image database, and subsequent 

 statistics, are biased with respect to the summer 

 months and periods when significant cloud cover was 

 present in the Gulf. 



