600 



FISHERY BULLETIN: VOL. 73, NO. 4 

 J I I 



OTHER INVERTEBRPTES 

 CEPHflLOPOOfl , 



— \ 1 r-^ 



TIME: 0600 0800 1000 1200 IHOO 



t t t t t 

 HAUL: 187 188 189 190 191 



-I 1 1 — 



1600 1800 2000 

 t t t t 

 192 193 194 195 



=F 



1 1 — 



2200 2400 0200 



t t t t 



196 197 198 199 



0400 0600 

 t 

 200 



Figure 4. -Shallow-tow (0-400 m) standing stock of micronekton abundance over 24 h. Time is plotted for midpoint of each tow. 



difference between the deep-tow stock and the 

 migrator stock. In general, the average weight per 

 migrating fish is greater than the weight of the 

 non-migrators, while the opposite holds for the 

 crustaceans and cephalopods, that is, the smaller- 

 sized members of the groups migrate. 



The occurrence of organisms larger than 10 g 

 (wet weight) per individual was highly variable 

 both with respect to abundance and biomass (Ta- 

 ble 9). None occurred in the groups of Cyclothone, 

 Sternoptychidae, Penaeidea, Euphausiacea, mis- 

 cellaneous Crustacea, or miscellaneous inver- 

 tebrates. The only large organism in shallow-day 

 tows was one tunicate. In deep tows, large animals 

 were less than 1% of the number of total 

 micronekton but 30% of the biomass. With respect 

 to biomass, about one-quarter of the total fishes. 



one-eighth of the total Crustacea, four-fifths of the 

 Cephalopoda and one-half of the other inver- 

 tebrates were made up of individuals larger than 

 10 g each. In shallow-night tows these proportions 

 are smaller for all groups except other inver- 

 tebrates which is about the same. 



DISCUSSION 



Restrictions 



The interpretation of our data must be con- 

 sidered with several restrictions. Larger, highly 

 mobile micronekton, especially fishes and 

 cephalopods, probably avoid or escape the trawl 

 (Pearcy and Laurs 1966; M. R. Clarke 1969; T. A. 

 Clarke 1973, 1974) resulting in underestimation of 



732 



