show that adult billfishes had been in the area 

 shortly before the sampling occurred, but the 

 implication of the transport of the larvae north- 

 ward by the Antilles Current is not so clear. We 

 have reason to doubt the existence of the strong, 

 steady, broad surface flow to the northwest which 

 has been assumed to be characteristic of the An- 

 tilles Current east of the northern Bahamas. 



In a recent analysis of six occupations of Stan- 

 dard Section A-7 (Figure 1) by U.S. Coast Guard 

 cutters, Ingham (1975) did not find a strong, 

 steady, broad surface flow attributed to the Antil- 

 les Current (Wiist 1924; Boisvert 1967). In a study 

 of directly measured values of the transport of the 

 Gulf Stream between the Florida Straits and Cape 

 Hatteras, Knauss (1969) noted that the transport 

 increases at a rate of about 7%/100 km, from 

 33 x 10 6 m 3 /s in the Florida Straits, to 63 x 10 6 m 3 /s 

 off Cape Hatteras. Increases of this magnitude 

 were also evident in earlier transport mea- 

 surements for the Florida Straits (Wiist 1924; 

 Montgomery 1941) and Cape Hatteras (Iselin 

 1936). Exactly how this increase takes place has 

 not been determined. Wiist (1924) and Iselin 

 (1936) felt that the Antilles Current makes a 

 significant addition (12xl0 6 m 3 /s) to the Gulf 

 Stream just north of the Bahama Islands, but 

 Stommel (1965) felt that this value for the con- 

 tribution of the Antilles Current was question- 



82 80 78 76 74 72° W 



/ 



\\) / STANDARD SECTION A7 



W/g) ISLANDS *~ ANTILLES 



I Ift I 



±^L 



36° N 



34 



32 



30 



28 



- 26 



able. It should be noted that Wiist's (1924) trans- 

 port to the northwest was approximately balanced 

 by two countercurrents on each side of the current 

 moving to the southeast. 



The geostrophic velocities and volume trans- 

 ports (Table 1 ) obtained by Ingham ( 1975) indicate 

 that the previous estimate (Wiist 1924) of the 

 transport of the Antilles Current is too large and 

 that a better estimate of the mean northward 

 transport is on the order of 8.6xl0 6 m 3 /s. The 

 difference in reference levels between Ingham 

 (1,000 decibars) and Wiist (800 decibars) does not 

 account for this discrepancy since Wiist's shal- 

 lower reference level would result in less transport 

 than Ingham, not more. In the six transects 

 measured by Ingham only one showed a net 

 transport large enough to account for the above 

 mentioned increase in the Gulf Stream. In ad- 

 dition, the net transport through the section was 

 highly variable, showing values of 3.4 and 

 6.4 xlO 6 m 3 /s southward in two of the transects. 

 Ingham (1975) suggested that some mechanism 

 other than the Antilles Current may account for 

 the increase in the Gulf Stream and that the 

 contribution of local wind-driven (Ekman) 

 transport be considered as a possibility, since the 

 mean direction of the winds in the vicinity would 

 produce a northward or northwestward drift. 



In order to determine this northward transport 

 contribution by locally wind-driven currents, 

 quarterly averages (January-March, April-June, 

 etc.) of Ekman transport values for 1946-73 were 

 obtained from the Pacific Environmental Group, 

 National Marine Fisheries Service, NOAA for 

 three locations northeast of the Bahama Islands, 

 along lat. 27°N at long. 78°W, 75°W, and 72°W 

 (Figure 1). These values were calculated from the 

 mean monthly atmospheric pressure field using 

 the method described by Bakun (1973) to deter- 

 mine the mean monthly wind stress on the ocean 

 surface and the resulting Ekman transport. The 

 quarterly mean meridional Ekman transports, 

 per unit length, for each position were averaged to 

 give a mean transport value for a hypothetical 



TABLE l.— Transports across Coast Guard Standard Section A-7 

 as reported by Ingham (1975). 



FIGURE 1. — Position of Coast Guard Standard Section A-7 in 

 relationship to surrounding currents and land masses. 



223 



