FISHERY BULLETIN: VOL. 80. NO. 1 



Table 1.— Summary of tow statistical information for the 1 m 2 and 10 m 2 MOCNESS (MOC-1, MOC-10) tows taken in 1977 at the 



nine station locations illustrated in Figure 1. D = Day; N = Night. 



mitted data were recorded on magnetic tape. 

 They were also processed by a shipboard com- 

 puter (Hewlett-Packard 4 2100) and plots of 

 depth versus temperature and salinity were pro- 

 duced. On Knorr 71, the 10 m 2 net was deployed 

 with a simplified electronics package which did 

 not have a conductivity sensor and which trans- 

 mitted data at a slower rate. For this latter sys- 

 tem, plots of depth versus temperature and angle 

 of the net were made with a Hewlett-Packard X, 

 Y, Y recorder. During all of these tows, net 

 speed, as indicated by the flowmeter, was closely 

 monitored and adjustments to the ship speed 

 and/or winch speed were made to keep the net 

 moving ahead at 2+0.5 kn (3.71+93 km/h). All 

 samples were preserved in 5-10% Formalin buf- 

 fered to pH 8.0 with sodium borate. 



For 162 of the 190 samples resulting from the 

 tows listed in Table 1, we sorted and counted the 

 entire sample for adult and adolescent (without 



"•Reference to trade names does not imply endorsement by 

 the National Marine Fisheries Service, NOAA. 



adult sexual characteristics) N. megalops. Very 

 large catches were split with a Folsom plankton 

 splitter (McEwen et al. 1954) and between one- 

 half and one thirty-second of the sample was 

 counted. Wet weights were determined either on 

 all or a sizable fraction of the sorted individuals. 

 Battered or disfigured individuals were ex- 

 cluded from this analysis. Individuals were blot- 

 ted on absorbent paper and then weighed to ±0.1 

 mg on a Cahn model 7500 digital top-loader mil- 

 libalance. Total body length (tip of rostrum to tip 

 of telson) was determined on a small subset of in- 

 dividuals from both the Knorr 65 and 71 collec- 

 tions in order to establish a relationship between 

 wet weight and length (Fig. 2) for subsequent 

 calculations of potential escape velocity based on 

 body length. The geometric mean regression 

 equation (Ricker 1973) which was fit to these 

 data is similar to those presented by Mauchline 

 (1967) for a variety of euphausiid species. 



In some comparisons of the sampling capabili- 

 ties of the two MOCNESSes and in the applica- 

 tion of Barkley's (1972) avoidance theory, we 

 have used the average numbers per 1,000 m 3 for 



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