FISHERY BULLETIN: VOL. 84, NO. 1 



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Figure 22— Depth versus relative abundance (as percent, by number, of total capture) for 

 the family Macrouridae, by individual cruise 



Comparison With Other Studies 



The comparison of this study with others in the 

 North Atlantic lends support to Marshall and 

 Iwamoto's (1973) hypothesis that the greatest diver- 

 sity of macrourids is in the bathyal tropical regions. 

 The number of macrourid species declines from 

 tropical to boreal regions. Marshall and Iwamoto 

 (1973) reported 32 macrourid species from the Carib- 

 bean and Gulf of Mexico, but only 22 species were 

 captured during our study (Table 2). Bullis and 

 Struhsaker (1970) found that Macrouridae was one 

 of the dominant families on the western Caribbean 

 slope between 201 and 400 fathoms (368-732 m). The 

 deepest stratum sampled was 451-500 fathoms 

 (825-914 m), and macrourids (9 species) comprised 

 about 67% of the individuals captured within these 

 depths. Within the same depths in the Norfolk Can- 



yon area the dominant macrourids (4 species) con- 

 tributed about 31% to the total catch. 



Merrett and Marshall (1981) remarked on the high 

 diversity (and apparent resource partitioning) of 

 macrourids from a tropical upwelling area off north- 

 west Africa and reported 26 species from there They 

 found 18 species on the slope (< 1,600 m), including 

 four species of Nezumia. Bathygadine macrourids 

 were important off Africa but virtually absent in our 

 study area. Thus macrourid diversity is probably 

 highest on the continental slope in the tropics, par- 

 ticularly in areas of higher productivity. In addition, 

 high diversity is manifested there at several tax- 

 onomic levels, from the species to the subfamily. 



Haedrich et al. (1975) reported the capture of 121 

 macrourid specimens (3 species) in 29 trawls off 

 Southern New England. Their trawl depths ranged 

 from 141 to 1,928 m. Their findings were similar to 



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