conditions that are likely to be useful in 

 studies of tuna ecology in the area. 



In the spring of I960 three kinds of surface 

 water met in the entrance of the Gulf of 

 California. If we assume that other years 

 and other seasons are similar, the entrance 

 is a complicated transition zone. It has not 

 been extensively studied or described. Roden 

 and Groves (1959) described the oceanography 

 of the Gulf proper from CalCOFI data, but 

 they had few data from the Gulf entrance. 

 Reid, Roden, and Wyllie (1958) described 

 the California Current system to the southern 

 tip of Lower (Baja) California, using CalCOFI 

 data. The annount of data decreases south of 

 Magdalena Bay (24° 30' N.), and is scanty 

 to the south of Cape San Lucas and Cape 

 Falso at the southern tip of the peninsula. I 

 have described one of the major oceanographic 

 features of the region, the Cape San Lucas 



frontal system (Griffiths, 1963, 1965), partly 

 fronn data of cruise TO- 60-1 and partly fronn 

 data of another cruise, TO-61-1 (April 1961). 

 Wyrtki (1966) summarized the available in- 

 formation on the oceanography of the eastern 

 Pacific; his paper on water masses (1967) 

 defines water types reported here. 



The area of cruise TO-60-1 is shown in 

 figure 1, which also shows the area of the 

 part of CalCOFI cruise 6004-B from which 

 data were used. 



The track of cruise TO-60-1 covers what 

 may be considered as the entrance to the 

 Gulf of California. Although cruise 6004-B 

 was outside this area, it was a most 

 useful source of contennporaneous data 

 about one of the main kinds of water in 

 the Gulf entrance. Such data were not 

 available for the area south of the en- 

 trance. 



Figure 1. — Chart showing the track of STOR cruise TO-60-1, May 1960 (— •— , full hydrocasts or 10-m. bottle casts; 

 — o— , between-station BT's) and part of the track of CalCOFI cruise 6004-B, April 1960 (--o--,fulI hydrocasts). 

 Areas of front studies are shown by hatching and labeled as fronts (1, 2, 3, 4). Special stations at front 2 are shown as 

 2.1, 2.2, and 2.3. Special stations at front 4 are shown as 4.1, 4.2, 4.3, and 4.4. 



