13. Statistical studies of interrelationships 

 of anomalies of sea level and associated vari- 

 ables (atn-iospheric pressure, wind compo- 

 nents, and surface temperature) were made, 

 and in part completed, in areas in and adjacent 

 to the eastern tropical Pacific where suitable 

 time series of data were available. This rep- 

 resents an effort to utilize data from shore 

 (tide gauge) stations in further studies of the 

 reaction of the ocean to atmospheric changes 

 (cf. 3, 4, 5, and 9 above). 



14. A statistical study of the reliability of 

 ocean measurements of temperature and salin- 

 ity was made. 



15. Work was begun on the life-history of 

 the red crab, Pleuroncodes planipes, which is the 

 predonninant 0"ganism in the micronekton of 

 Baja California waters and the main item in 

 the diet of tropical tuna in that area. 



Finally, much attention was given to devel- 

 opment and improvement of oceanographic 

 techniques (16-18), as follows: 



16. Deep-moored unmanned ocean stations, 

 capable of making frequent observations of 

 several properties of ocean and atmosphere 

 in the same locality over periods of at least 

 3 months, are desirable for understanding and 

 necessary for forecasting in the kind of fish- 

 eries oceanography exemplified by the present 

 program. Such a station, developed to measure 

 wind velocity, wind direction, and sea tempera- 

 ture at various depths in the upper 120 m., 

 each hour, was tested in Baja California and 

 the Gulf of Tehuantepec in 1958, but was 

 unsuccessful. Some of its features were re- 

 designed, and it performed satisfactorily in 

 ocean tests during I960. Another type of 

 moored station, designed specifically for 

 measuring temperatures at various levels 

 throughout the whole water column, was used 

 with some success in 1960. All these types 

 recorded, but did not transmit, their meas- 

 urements. 



RECOMMENDATIONS FOR FUTURE WORK 



Further work is recommended along the 

 following broad lines, mainly in continuation 

 of investigations reported above. The items 

 are not necessarily in order of importance. 

 It should be borne in mind that unforeseen 

 circumstances such as new developments in 

 oceanographic technique, or changes in the 

 ocean or the fishery, might dictate major 

 changes in the program. 



1. Further statistical analysis is needed to 

 show which combinations of variables have 

 the greatest value for predicting abundance 

 of tuna in various areas and seasons. This 

 would involve linking up the results presently 

 being sought in different parts of the energy 

 chain. In particular, the connections between 

 tuna and environmental factors directly affect- 

 ing them need more study; this would be 

 greatly facilitated if some information about 

 tuna abundance could be obtained at precisely 

 the same tinne and place as ocean properties 

 are being measured on research ships, and 

 for this reason the Bureau of Commercial 

 Fisheries' own study of the use of sonar for 

 detecting tuna is of great potential importance. 

 Another special need is for more statistical 

 work on interrelationships of atmospheric 

 and oceanic properties in the eastern tropical 

 Pacific. 



2. Basic research is required in most 

 parts of the tuna energy chain in order to 

 understand the forms that empirically deter- 

 mined statistical relationships have and the 

 limits within which they are likely to be 

 satisfactorily predictive; to suggest combi- 

 nations of variables with a view to finding 

 new or improved relationships; and to assist 

 in making certain kinds of observations quan- 

 titative. In particular, more information is 

 needed about the relationship of phytoplankton 

 to its physico-chemical environment, espe- 

 cially the chemical nutrients linniting its 

 growth. 



17. Work was done to develop, improve, 

 or test methods of nneasuring submarine 

 daylight extinction, standing crops of chloro- 

 phyll a and micronekton, and concentrations 

 of various chemical nutrients; and methods 

 of making enumeration or biomass measure- 

 ments of components of the phytoplankton, 

 zooplankton, and micronekton, some of which 

 might be more useful in statistical relation- 

 ships than measurements of the unsorted 

 material. 



18. The Roberts current meter was suc- 

 cessfully nnodified for subsurface current 

 measurements. 



3. Useful relationships will differ from 

 area to area depending, fundamentally, on 

 the particular physical features and processes 

 of atmosphere and ocean in those localities. 

 In some areas, it is even possible that non- 

 quantitative relationships could be of value. 

 For this reason the detailed oceanographic 

 survey work being done in special fishing 

 areas should be expanded to cover more 

 physically distinct types of ocean environ- 

 ment, such as dome areas, upwelling areas, 

 island and bank areas, and front areas. It 

 seems logical and necessary that the greater 

 part of this work be carried out north of the 

 Equator, as hitherto, as long as funds restrict 

 cruise time to less than 3 months per year. 



44 



