FISHERY BULLETIN: VOL. 73, NO. 2 



Figure 7.-700-mb heights and departures from normal, tens of feet, January 1949. Major departures are enclosed in 



boxes. 



troughs and ridges in the upper air circulation may 

 have been related to air-sea interaction processes 

 in the Pacific Ocean. 



It is interesting to speculate on the physical 

 consequences following the development of a 

 large-scale cold sea-surface temperature anomaly 

 in the v^^inter of 1957-58 in the Gulf of Mexico and 

 v^estern Atlantic. It is quite possible that further 

 investigation vi^ill show differences of flow in the 

 Gulf Stream. The fact that the anomaly developed 

 in winter suggests that the water to the depth of 

 the thermocline may be affected. A large cold 

 mass of water of this type alters the density dis- 

 tribution over a large area and thus alters the 

 surface circulation. The authors have noted an ap- 

 parent drift of the anomaly away from the U.S. 

 east coast northeastward until the early summer 

 of 1958 when the surface anomalies were ob- 

 scured, although it may be quite possible and even 



likely that the deeper waters were still colder than 

 usual. The effects on Europe of this cold water 

 mass after a period of eastward drift can only be 

 speculated at this time. The fact that the anomaly 

 could be traced for a time following its formation 

 suggests an interesting possibility for further 

 research. 



The biological consequences of such large-scale 

 air-sea interactions are even more complex. The 

 effect of the warm sea temperature pool in the 

 eastern Pacific in 1957 and 1958 on fish populations 

 is well documented by Radovich (1961). Southern 

 species were found much farther north than nor- 

 mal in the temperate northeastern Pacific ap- 

 parently in response to the warm sea tempera- 

 tures. In the western Atlantic and Gulf the effects 

 of the cold anomaly were less evident although 

 there is a suggestion from the work of Williams 

 (1969) that the shrimp populations were affected. 



314 



