Goa 



19-24 September— phase I (5-1 2°S, 



results not included) 

 12-25 October —phase II (12-17°S) 

 12-17 November —phase III (12-17°S) 



Rockaway: 



29 September-3 October 



-phase I (Angola 

 Dome survey, results 

 not included here) 

 -phase II (0-6°S) 

 -phase III (11-17°S) 



15-30 October 



1 1-21 November 



25 November-2 December— phase IV (0-4°S) 



During phase II of the cruises in October-December 

 1968 the three ships were at sea simultaneously, oc- 

 cupying stations along onshore-offshore transects 

 1 00-1 20 nm (1 85-200 km) in length in the area from the 

 equator to 17°S." Goa covered the southern portion 

 (12-1 7°S), Undaunted the central portion (6-1 2°S), and 

 Rockaway the northern portion (0-6°S). 



During phase III, the ships worked together in an 

 area from 1 1°to 17°S in an effort to describe the antici- 

 pated southward movement of an oceanic front along 

 the Angola coast. The Rockaway occupied stations 

 along four long north-south transects, while the Goa 

 and Undaunted worked along a sawtooth track in the 

 same area. 



During phase IV, only the Rockaway gathered data, 

 while reoccupying stations between 4°S and the 

 equator. 



DATA ACQUISITION 



Water Temperature 



Water temperature was measured by reversing 

 thermometers, expendable or mechanical bathyther- 

 mographs (XBT or BT), in situ salinity-temperature- 

 depth recording systems (STD), recording thermo- 

 graphs, and bucket thermometers. 



Salinity 



Salinity was measured in situ by means of an STD or 

 by shipboard or laboratory analysis of water samples 

 collected from casts of Niskm or Nansen bottles. 



Dissolved Oxygen Content 



A modified Winklertitration (Strickland and Parsons, 

 1965) was used on board the Undaunted and Rocka- 

 way to determine the concentration of dissolved ox- 

 ygen in water samples collected with Nansen orNiskin 

 bottles. 



Inorganic Phosphate Content 



Samples of seawater were analyzed for their content 

 of dissolved inorganic phosphate either on board the 

 research vessel (Rockaway) or in the laboratory after 

 preservation by freezing (Undaunted). The shipboard 

 analysis generally followed methods prescribed by 

 Strickland and Parsons (1965). The laboratory method 

 used on preserved water samples from Undaunted 

 6801 was a modification of a dual reductant analysis 

 (Van Landingham, 1958) involving colorformation and 

 stabilization by a stannous chlonde-hydrazine sulfate 

 reducing agent. Preserved water samples from Un- 

 daunted 6802 were analyzed according to the proce- 

 dure specified by Strickland and Parsons (1 968) using 

 a Beckman DU spectrophotometer. 



Primary Productivity 



Estimates of primary productivity were made each 

 day on board the Rockaway and Undaunted by 

 measuring the amount of carbon fixed during 24 hr in 

 incubation of seawater samples inoculated with C-14 

 carbonate. The water samples were collected at local 

 apparent noon at selected light-extinction levels. They 

 were placed in deck mounted incubators, fitted with 

 filters to simulate the extinction levels, in a bath of 

 running seawater at ambient sea surface temperature. 

 After incubation the samples were filtered and re- 

 sidues desiccated and frozen until subsequent anal- 

 ysis in a laboratory ashore. 



Zooplankton 



Double oblique tows of 1-m plankton nets fitted with 

 flow meters and bathykymographs were made in the 

 upper 200 m (water depth permitting) to capture rep- 

 resentative samples of zooplankton. Biomass esti- 

 mates, per unit volume of water filtered, were obtained 

 by the displacement method described by Tashiro and 

 Hebard (1969). 



Nekton 



Near-surface tows of a 6-ft Isaacs-Kidd midwater 

 trawl were made on selected stations from the Un- 

 daunted in an attempt to sample the forage organisms 

 available to surface-schooling tunas. 



Tunas 



Samples (up to 100 individuals) were collected by 

 hook and line from surface schools of tuna whenever 

 possible from the Undaunted. Samples of muscle tis- 

 sue, gonads, blood, and eyes were taken from the fish 

 after they were measured, weighed, and sexed. 



