at an average speed of 9 knots. The Gilbert, 

 as a part of her primary mission, trolled during 

 daylight hours using 6 lines at speeds of from 

 6-8 knots. The coinmon and scientific names 

 for each species of fish caught from either the 

 Gilbert or the Smith are listed in table 6. The 

 trolling catch of the Smith is listed in table 7; 

 that of the Gilbert in table 8. Both vessels 

 maintained a standard wheel watch for birds, 

 fish, and aquatic manrunals; the results of these 

 observations are given in tables 9 to 12. 



The Gilbert fished 10 tuna, schools by 

 live-bait, pole -and -line methods, trolled a total 

 of 424 line -hours by direct trolling at vessel 

 speeds between 6.4 and 9.8 knots, and fished a 

 total of 20 longline stations. Sixty baskets of 

 1 1 -hook gear were used at each longline station. 

 The position of each station is shown in figures 

 2 and 3; the catch results are summarized in 

 tables 13 and 14. The catch statistics for the 

 pole -and -line fishing are given in table 15. A 

 more complete report describing the Gilbert's 

 fishing methods and results will be published 

 in the near future. 



At 7 baiting stations located at positions 

 shown in figure 3, a total of 235 buckets of 

 Marquesan sardines ( Harengula vittata) and 8 of 

 goat fish ( Upeneus parvus ) were captured. The 

 catch at each station is listed in table 16. A 

 detailed report on the distribution and abundance 

 of bait in the Marquesas Islands will be prepared 

 following the January -March 1957 cruise of the 

 Gilbert to this area. 



Miscellaneous 



The EDO depth recorder was used on 

 both vessels to study the deep scattering layer. 

 The Gilbert obtained soundings at various posi- 

 tions in the area of the Marquesas Islands. 



The Hardy Continuous Plankton Recorder 

 was towed by the Gilbert for five days (1, 187 

 miles) from Lawson Bank, Marquesas {see fig. 

 3) to S-SO'N. , 150°19'W. The recorder became 

 inoperative during the fifth day of continuous 

 towing . 



The Gilbert field party arranged for 

 POFI to obtain copies of the records from the 

 weather stations on Nuku Hiva and Hiva Oa and 

 for a Marquesan weather observer to take 

 weekly sea surface tem^peratures and salinity 

 samples. The Smith field party serviced the 

 weather instruments at the Christmas Island 

 station. 



The Gilbert made night-light collections 

 near the islands of Eiao and Hiva Oa (see fig. 3). 



LABORATORY PROCEDURES 



Oceanographic Processing 



The salinity samples were analyzed by 

 Fajans ' modification of the Mohr method (Van 

 Landinghami 1957). The phosphate samples 

 were analyzed by the hydrazine sulphate modi- 

 fication of Denige's method (King et al. 1957). 

 Stations 1 to 6 were deleted when samples were 

 contaminated by brine solution during freezing. 

 After station 6 all sannples were dry frozen. 

 An accident in the laboratory contaminated 

 stations 14, 17 and 25. Stations 35, 55, 62 and 

 66 were deleted as examinations indicated they 

 were erroneous. It should be pointed out that 

 further analysis may necessitate additional 

 station deletions . As previously mentioned, the 

 dissolved oxygen analyses were connpleted 

 aboard the Smith . 



The oceanographic station data were 

 processed with the techniques described by 

 Montgomery (1954), Montgomery and Wooster 

 (1954), Stroup (1954), and King et al. (1957). 

 The observed data from each station are listed 

 in table 17; the station curves are reproduced 

 in figure 4. 



Carbon Fixation Measurements 



A detailed description of laboratory 

 procedures for the determination of the quanti- 

 ty of C^^ photosynthetically fixed per unit of 

 time, and the associated calculations has been 

 given by King et al. (1957). The counting, done 

 with a Tracerlab SC16 windowless gas flow 

 counter and a Tracerlab 1000 -Scaler of a 

 Nuclear Chicago 161A-Scaler, was performed 

 at the University of Hawaii under the super- 

 vision of M. S. Doty. The results of the C^^ 

 measurements are given in table 18. 



Zooplankton Samples 



The displacement volumes of the plankton 

 from the oblique tows made by the Smith and 

 the surface tows naade by the Gilbert are given 

 in tables 19 and 20. These volumes were 

 detern^ined after removing all fish eggs and 

 larvae as well as all "jellies" greater than 2 

 cm. in length. The details of the method are 

 described by Hida and King (1955). 



The flowmeter used with the45-cnn. net 

 recorded to 10, 000 revolutions and then repeated 

 the cycle. The upper limit of 10,000 was some- 

 times exceeded during the 30 -minute oblique 

 tows; thus it was necessary to calibrate the 

 flowmeter in the 45-cm. net against that in the 

 1 -meter net. The resultant correction factors 



