Table 6. — Means and medians of standardized micronekton 

 volumes {millililers per 1,000 m.^) from stations shown in 

 figures 1, 6, 7, and 8, grouped by distance in miles from 

 the mainland coast 



[Data from tables 1 and 6; n means number of stations] 



' TO-58-1 stations 1, 48 to 146; TO-60-2 stations 1 to 9, 23 to 30. 42 to 50. 

 ! TO-58-1 stations 3 to 16, 29 to 46; TO-60-2 stations 11 to 19, 32, 38, 55. 

 > TO-58-1 stations 18 to 27; TO-60-2 stations 35, 59 to 85. 



T.A.BLE 7. — Means of standardized micronekton volumes 



from two groups of the 40 onshore stations of table 6 



[Data from table 1] 



' TO-58-1 stations 49, 63, 77, 81, 142, 144B, 146: TO-60-2 station 6. 

 ' Stations in table 6, footnote 1, except those in footnote above. 



from the eastern tropical Pacific because of the 

 differences in sampling gear. 



The distribution of leptocephali, the second 

 largest gi"Oup by volume among the fishes, is shown 

 in figure 10. Standardized volumes are again 

 higher near the coast than offshore (table 6), but 

 they decline toward the south (table 5) and pos- 

 sibly also to the north. On a cruise made in June 

 1964, the mean standardized volume of leptoceph- 

 ali recorded at seven stations along the west coast 

 of Baja California was < 0.1 ml. per 1,000 m.^ 

 Leptocephali have been recorded in micronekton 

 catches off the United States west coast and in the 

 central Pacific, but apparently in much smaller 

 quantities than in the coastal waters of tlie eastern 

 tropical Pacific (Aron, 1959, 1962a; Pearcy, 1964; 

 King and Iversen, 1962). 



The distribution of gonostomatids — mainly 

 Vinciguerria spp., as shown in table 3 — is similar 

 in its general features to the distribution of total 

 fishes (fig. 6) and is, therefore, not shown. Vol- 

 umes decline from onshore to offshore (table 6), 

 and the volumes in table 5 show no obvious change 

 with latitude for stations located at similar dis- 

 tances from the coast. 



Similar data for two of the more common crus- 

 taceans, euphausiids and stomatopod (squillid) 

 larvae, are given in figures 11 and 12. Euphausiids 

 (fig. 11) are more abundant onshore than offshore 

 (table 6) and may increase in biomass toward the 

 poles. Figure 11 and table 5 show higher concen- 

 trations south of the Equator than elsewhere, and 

 similar concentrations occurred on a cruise made 

 in June 1964 along the west coast of Baja Cali- 

 fornia (mean standardized volume for seven sta- 

 tions, 14.6 ml. per 1,000 m.^) . Euphausiids are well 

 represented in the material from Pacific regions 

 farther north and west (Aron, 1959, 1962a; King 

 and Iversen, 1962), although, again, the nature of 

 the collecting gear used in those regions prevents 

 quantitative comparisons with the eastern tropical 

 Pacific. 



The distribution of volumes of stomatopod lar- 

 vae (fig. 12) is similar to that of leptocephali: 

 higher onshore tlian offshore (table 6), and di- 

 minishing polewards. Figure 12 and table 5 show 

 low concentration south of lat. 10° S., and similar 

 concentrations occurred on a cruise made in Jmie 

 1964 along the west coast of Baja California 

 (mean standardized volume for seven stations, 0.1 

 ml. per 1,000 m.^). Stomatopod larvae were not 

 mentioned by Aron (1959, 1962a) in his reports on 

 micronekton collections west of the TTnited States. 

 King and Iversen (1962) obtained them fairly reg- 

 ularly in central Pacific waters between about lat. 

 19° S. (the southern limit of their sampling) and 

 lat. 35° N. ; they were not taken north of lat. 35° N. 



The distribution of sergestids is similar in its 

 general features to the distribution of stomatopod 

 larvae and is, therefore, not shown. Volumes de- 

 cline from onshore to offshore (table 6), and from 

 the tropics toward the poles; all volumes ^ 1.0 ml. 

 per 1,000 m.' in table 5 are from stations located 

 between lat. 15° N. and 15° S. 



92 



U.S. FISH AND WILDLIFE SERVICE 



