mm wire mesh and covered by either burlap or canvas 

 over the arched upper surface. On each sampling day 

 one string of three traps was set at each of three sam- 

 pling depths, 366, 732, and 1,097 m (200, 400, and 

 600 fathoms). Strings were set in the afternoon and 

 recovered the next morning with a normal soaking 

 time of between 16 and 20 h. Three species of 

 Heterocarpus — H. ensifer, H. laeuigatus, and H. longi- 

 rostris — accounted for the majority of the catch. 

 Shrimp referable to both H. laeuigatus and H. lon- 

 girostris were present in the catches throughout the 

 cruise, but during the major part of the cruise they 

 were considered to be the same species and recorded 

 as "H. laeuigatus." These two species were recorded 

 separately only on the last two series of sets (two 

 strings at each of the three experimental depths). In- 

 formation on the catch for these six strings is pre- 

 sented in Table 1. 



The species with the highest catch rate (kilograms 

 per trap) was//, laeuigatus; H. ensifer and//, longiros- 

 tris followed with catch rates about half that of H. 

 laeuigatus. Heterocarpus laeuigatus was also the 

 largest species caught, averaging 25 individuals/kg. 

 Heterocarpus longirostris was next, averaging 47/kg, 

 and H. ensifer was the smallest, averaging 146/kg. 

 Differences in the reproductive biology of these 

 species are suggested by the differing proportion of 

 egg-bearing females present in the catch for each 

 species. The percentage of berried females was high- 

 est for//, ensifer at 33% whereas that for//, longiros- 

 tris was only 19%, and no berried//, laeuigatus were 

 caught. It is quite likely that these values change on a 

 seasonal basis. Vertical separation of the three spe- 



cies was complete for the last six strings set. Het- 

 erocarpus ensifer was caught only at 366 m, H. laeui- 

 gatus only at 737 m, and H. longirostris only at 

 1,097 m. 



Though not documented due to confusion in the 

 species identification of//, laeuigatus and//, longiros- 

 tris during most of the cruise, there is reason to 

 believe that species separation by depth was essen- 

 tially complete for the entire cruise. Table 2 lists the 

 catch of the three species of Heterocarpus for the en- 

 tire cruise excluding the last six strings. Heterocarpus 

 ensifer was found almost exclusively at 366 m with a 

 few being caught at 732 m. Mean size and percentage 

 of berried female values for the entire cruise (Table 

 2) are very similar to those obtained from the last six 

 strings (Table 1) for//, ensifer (11 2/kg compared with 

 146/kg and 31% compared with 33%, respectively). 

 Similarly, values of mean size and percent berried for 

 H. laeuigatus in Table 1 match closely those for the//. 

 laeuigatus/H. longirostris group at 732 m (and the few 

 at 366 m) in Table 2 as do the values for//, longirostris 

 (Table 1) with those at 1,097 m (Table 2). This sup- 

 ports the assumption of vertical separation of these 

 three species. 



Both//, laeuigatus and//, ensifer are considered to 

 be commercially important species and have sup- 

 ported small local fisheries in some Pacific areas 

 (Hawaii State 1979). Based on the results of this 

 cruise, H. longirostris compares favorably with these 

 two species as one with commercial potential. It is 

 very close to H. ensifer in relative abundance (mean 

 catch in weight per trap) and second, to//, laeuigatus, 

 in mean size. Heterocarpus laeuigatus is first in both 



TABLE 1. — Catch of Heterocarpus ensifer, H. laeuigatus, and H. longirostris for the last 



six strings of the cruise. 



435 



