The first (labeled A) and third (C) samples taken with the DDPS were 

 typically horizontal, while the second (B) and last (D) were oblique. The 

 configuration of the towpath for collection 7-TI (Figure 2) is nearly ideal 

 because the two horizontal samples (A and C) show almost no vertical excursion. 

 The oblique samples (B and D) are of little value in determining precise depth 

 limits of occurrence of organisms. The final oblique sample to the surface is of 

 particularly little value since usually the shortest possible time is used in getting 

 the net up to the surface where it fishes and bounces around for varying lengths 

 of time before it can be brought aboard. Nevertheless, keeping these limitations 

 in mind, the oblique samples may often give important indications of animal 

 abundances. 



The fish from all collections were sorted and identified to species. The 

 invertebrates from all collections except the March-April 1967 cruise were 

 sorted to major groups. The biological data were analyzed on the basis of 

 geographic area. 



Knowing the approximate speed of the ship, the length of time the net 

 was towed for each sample and using Pearcy and Lours' (1966) figure of 2.89 m^ 

 for the mouth opening of the six-foot I KMT, with their estimated efficiency of 

 85 percent, it was possible to calculate the volume of water filtered. Estimates 

 were then made of fish concentration per 1000 m*' of water excluding larval and 

 post larval specimens. The MPS had a mouth opening of 0.5 m^ and the efficiency 

 was assumed to be 100 percent. 



Explosive acoustic measurements of volume reverberation were made 

 during all cruises discussed above. During the cruise in March-April 1967, 

 when the quality of the biological data was best, an intermittent loss of sensi- 

 tivity developed in the hydrophone and the acoustic data eventually had to be 

 discarded. 



RESULTS 



A. Gulf of Mexico 



Collections in the Gulf of Mexico were made on two cruises: June 

 1966 aboard the USNS LYNCH (T-AGOR-7) and March-April 1967 aboard the 

 USNS SANDS (T-AGOR-6). The LYNCH took only four oblique open net hauls 

 from 90 meters to the surface during the night, whereas much more data are 

 available from the SANDS trip. 



Oceanographically, the eastern part of the Gulf of Mexico is dominated 

 by a current loop that is part of the Yucatan Current — Florida Current — Gulf 



