(Van Schuyler and Hunger, op.cit.)/ o\\ indicate that this area would probably 

 belong to Class III. In either case, both the Gulf of Mexico and Area Bravo 

 may be considered as being in regions of rather low productivity. 



The relationship between primary productivity and standing crop, 

 particularly standing crop of zooplankton, is problematical (Strickland, 1960, 

 p. 101). Steeman Nielsen and Jensen (op.cit., p. 117) point to a high correla- 

 tion between their measurements of primary productivity and standing crops of 

 both phytoplankton and zooplankton. Jespersen (1923, Figure 1 and 1935, 

 Figure 4) showed that the central Sargasso Sea, at least, had much lower 

 macroplankton volumes than the surrounding waters. Our own collections in 

 both Area Bravo and the Gulf of Mexico, although not very stringent in a 

 quantitative sense, contained much smaller quantities of organisms than our 

 collections for comparable lengths of time in an area of high productivity, the 

 Norwegian Sea. Thus, our data are at least consistent with the concept that 

 both Area Bravo and the Gulf of Mexico are regions of low primary productivity. 



CONCLUSIONS 



From our midwater collections in the Gulf of Mexico and western North 

 Atlantic we can conclude the following: 



1 . The fish in the night surface scattering layers in the Gulf of Mexico 

 tend to be concentrated in a narrow depth range. This depth of abundance may 

 depend somewhat on the water temperature. 



2. Myctophids and gonostomatids are the most abundant kinds of fish 

 in our collections. 



3. A few species, often only 2 or 3, out of the total number of fish 

 caught, usually make up the majority of the fish catch. 



4. No consistent correlation is found between the depths, kinds, and 

 numbers of animals taken and occurrence of 12 kHz deep scattering layers. At 

 least part of the reason for this is the obvious inefficiency of the nets that were 

 used to sample the organisms at a given depth. 



5. The concept that the Gulf of Mexico, Gulf Stream, and Sargasso 

 Sea waters are of low productivity, is upheld by the relative sparseness of 

 organisms in our collections. 



6. Our collections are consistent with previously reported correlations 

 between an oxygen minimum layer and an abundance of organisms. 



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