Oceanography and the Marine Fisheries 



by Milner B. Schaefer 



Director, Institute, of Marine Resources 



University of California 



La Jolla, California 



Oceanography, for fisheries or any other purposes, is con- 

 cerned with describing the distribution of physical, chemical 

 and biological properties and their changes in space and time, 

 and with understanding the forces and processes that bring 

 these things about, and the interrelationships among all of the 

 different factors. The descriptive phase, that is determining 

 what happens when and where, is of considerable use to the 

 development of the commercial fisheries. However, under- 

 standing why brings the application of the observations to much 

 firmer ground, especially when it comes to reliably forecasting 

 future events. 



At the present stage, the descriptive aspects of oceanography 

 are rather better advanced than the analytical aspects, but 

 large and rapid advances have been made in both since the 

 end of the last great war, and particularly during the past 

 decade. During this period we have obtained a vastly in- 

 creased store of observational data, and there have been large 

 increases in our understanding of the basic physics, chemistry, 

 and biology of the oceans, and of the ecology and behaviour 

 of populations of harvestable living organisms. The ocean- 

 ographers' increasing capabilities to provide the information 

 and understanding on which to base fisheries development is 

 due in no small part to new developments in precise, rapid 

 and sophisticated instrumentation and methods of observation. 

 Observational coverage of the ocean has become more exten- 

 sive and more intensive, both by the employment of many more 

 research vessels, and by development of improved systems of 

 data acquisition from the fishing fleets, merchant fleets, weather 

 satellites, and so forth. Finally, we are enabled quickly to digest 

 vast quantities of new information because of the development 

 of rapid data processing systems, using high speed computers. 



Oceanographic knowledge assists in increasing the harvest 

 of the sea in five ways: ( 1 ) Location of new highly productive 

 fishing areas. (2) Identification and location of promising 

 unutilized fishery resources. (3) Providing the fisherman 

 information which he can use to improve his tactical scouting 

 and catching operations. (4) Forecasting space and time 

 variations in the abundance and catchability of fish popula- 

 tions. (5) Providing the scientific basis of rational manage- 

 ment of the heavily exploited fisheries. I will deal here with 

 the first four of these topics, passing over the fifth, despite its 



very great importance, because of the limited time allotted 

 for this presentation, and because it is a subject with which 

 I am sure you are already very familiar. 



Location of new productive fishing areas 



Until 10 or 15 years ago, new fishing grounds were, with 

 few exceptions, discovered by venturesome fishermen, and 

 occasionally by governmental fishery explorations, trying out 

 new areas, with little or no help from physical or biological 

 oceanography. Following the discovery of new fishing areas 

 by such exploratory fishing, the oceanographers came along 

 and found out why these areas were highly productive. In 

 each case, they found that the rich fisheries occur at or near 

 those locations where large quantities of organic matter are 

 produced by the phytoplankton, due to fertilization of the 

 sunlit upper layer of the sea by upwelling, mixing along cur- 

 rent boundaries, winter overturn, stirring of nutrients up from 

 shallow bottoms, or other physical processes. With increased 

 capabilities for studying the ocean circulation, for directly 

 measuring phytoplankton productivity, for assessing abundance 

 of larger organisms using underwater sound and other tech- 

 niques, and with increased understanding of why the fertile 

 ocean areas are fertile and the desert areas are desert, the ocean- 

 ographers have become of more use in pioneering in the loca- 

 tion of promising new fishing areas. 



For example, the northwest coast of Africa has long been 

 known to be a region of strong coastal upwelling, and measure- 

 ments of basic productivity and standing crops of phytoplank- 

 ton indicated that there should be abundant populations of 

 organisms which might be harvestable by the commercial fish- 

 eries. This led to exploratory expeditions by the Russians, 

 and more recently by others, including some from the United 

 States, to examine into the fishery potential of this area in re- 

 lation to oceanographic factors. In consequence, there have 

 been discovered sizeable populations of tunas, of Sardinella, 

 and of various demersal species as well. 



Investigations of the physical and biological oceanography 

 of the equatorial Pacific, in advance of and along with ex- 

 ploratory fishing operations, have greatly accelerated the devel- 



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