FISHERY BULLETIN: VOL. 73, NO. 4 



Table 8.-Mean biomass per animal, grams wet weight, for the 0- 

 to 1,200-m water column, vertical migrators (Table 7), and non- 

 migrators (animals residing deeper than 400 m at night). 



'0- to 400-m night stock minus 0- to 400-m day stock >0- to 

 1,200-m stock. 

 20- to 400-m day stock >0- to 400-m night stock. 

 ^Siphonophores were not enumerated. 



single-cruise data. In other parts of the world, 

 investigators have reported seasonal biomass 

 fluctuations of tw^o- to sevenfold for some 

 micronekton groups (Legand 1969; Blackburn et 

 al. 1970; Tranter 1973), and abundance fluctuations 

 of some species up to fifteen- to fortyfold (Pearcy 

 1964; Legand et al. 1970). Previous work in 

 Hawaiian waters has demonstrated temporal 

 variability in primary productivity (Gordon 

 1971:1132), epipelagic zooplankton standing stock 

 (Nakamura 1967; Shomura and Nakamura 1969), 



and such mesopelagic micronekton as myctophids 

 (T. A. Clarke 1973) and stomiatoids (T. A. Clarke 

 1974). The limited data available suggest at least 

 twofold temporal fluctuations in micronekton 

 standing stocks might be expected in Hawaiian 

 waters. At this time we cannot predict seasonal 

 oscillations in standing stock. Thus, until better 

 seasonal data are available, our reported standing 

 stock and faunal composition values should only 

 tentatively be considered characteristic for 

 Hawaii. 



Standing Stock 



On the basis of fish distributions, Amesbury 

 (1975) has definied the 400- to 1,200-m depth range 

 off Hawaii as the mesopelagic zone. Very few 

 animals have been taken deeper than 1,200 m in 

 opening-closing tows. Thus, standing stock values 

 determined from our deep tows are probably 

 reliable estimates for the micronekton of the 

 whole water column except near-bottom waters. 



In spite of the shortcomings, the data add con- 

 siderably to our knowledge of micronekton 

 especially because we sampled nearly the whole 

 depth range of the fauna, used a fully lined net 

 with small mesh, towed at a relatively high speed, 

 sampled when the moon had a minimal effect on 

 avoidance (cf. T. A. Clarke 1973), took several 

 sample replicates, monitored sampling volume and 

 depth, and determined standing stocks for all 

 components of the catch. The general lack of diel- 

 related avoidance agrees with the findings of T. A. 

 Clarke (1973) and Atsatt and Seapy (1974) but is in 

 contrast to the results of Pearcy and Laurs (1966). 



Table 9.-Mean standing stock of micronekton larger than 10 g (wet weight)/individual, by group, a. No. organisms/100 m- ocean 

 surface, h. Grams biomass/100 m- ocean surface. Standard deviation in parentheses. 



734 



