168° 



161° 



162° 



START ,,1 IV' 



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/? 



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© 



" ' fjO SEPT V^y ^ /-<N 700. 



FINISH X 



69°- 



Figure 1.— Positions and se- 

 quence of trawling stations dur- 

 ing WEBSEC-70. Circles indi- 

 cate stations where Isaacs-Kidd 

 midwater trawl was used; 

 squares indicate otter trawl was 

 used. (From Quast, 1972.) 



they were stored in 40'f isopropyl alcohol. Each sample 

 was examined first in its entirety for rare species. For 

 small samples, total counts were made for each species of 

 invertebrate, and maximum and minimum size ranges 

 were recorded. When large numbers of euphausiids or 

 mysids were present, the collections were subsampled 

 with a Folsom plankton splitter (McEwen et al. 1954). 

 The subsamples always contained more than 500 in- 

 dividuals. 



Identifications (to species when possible) were based 

 on the following taxonomic references: Banner (1948a 

 1948b, 1950, 1954); Barnard (1958, 1962a, 1962b, 1962c 

 1964, 1973); Boden et al. (1955); Bowman (1973, 1960) 

 Brodskii (19.50); Coe (1904, 1905); Dawson (1971); Dun 

 bar (1954); Gurjanova (1951); Holmquist (1959, 1965) 

 Leung (1971); G. E. MacGinitie (1955); N. MacGinitie 

 (19.59); Naumov (1960); Rathbun (1904); Sars (1895, 

 1900); Shoemaker (1955); Vanhoffen (1906); and Zim- 

 mer (1926). Except for decapod shrimps, lengths are 

 greatest body lengths to the nearest millimeter and do 

 not include antennae, rostra, or tentacles. Decapod 

 shrimp lengths are for the carapace (insertion of eye to 

 dorsal posterior margin). Displacement volumes to the 

 nearest 0.5 ml were taken on the drained lots of each 

 species sorted from a sample. The volumes were 

 measured with 10-, 25-, 100-, or 500-ml graduated 

 cylinders. All sorting and measuring was done 1-4 yr after 

 the specimens were collected; thus shrinkage due to 

 preservation was stabilized. Displacement volumes were 

 obtained only for samples processed in the last 4 mo of 

 sorting. 



RESULTS 



The 81 samples from the 20 midwater trawl stations 

 contained 103 specimens of invertebrates (Table 1). 

 Amphipods had the greatest number of species (35) and 

 decapod shrimps the second largest (14). The number of 

 invertebrate species per sample ranged from 4 to 40 

 (mean, 17). The scyphomedusans and hydromedusans 

 discarded in the field contributed most to the volume of 

 the catches. In the preserved material, euphausiids and 

 mysids were the most abundant invertebrates and the 

 major contributors to the biomass (Appendix Table 2). 



Thirty-three species of invertebrates were identified 

 from the two samples taken by the 3-m otter trawl at 

 station 8 (Table 2). The list of invertebrate species from 

 station 8 plus the benthic invertebrates taken in the mid- 

 water trawl samples supplement the more extensive lists 

 of benthic invertebrates from the southeastern Chukchi 

 Sea given by McCauley (1964), Sparks and Pereyra 

 (1966), and Naidu and Sharma (1972). Three species of 

 gastropods, 4 bivalves, 2 mysids, 2 isopods, 12 

 amphipods. 9 decapod crustaceans, and 1 ascidian were 

 collected by the otter trawl. 



DISCUSSION 



The three sizes of meshes in the Isaacs-Kidd mid- 

 water trawl used in the sampling were 3-mm cod end, 6- 

 mm rear section, and 38-mm forward section. Some of 

 the invertebrates captured were so small that many of 

 them undoubtedly passed through the larger meshes. Al- 



