376 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1950 



Sometime between the fifth and ninth year of life the oyster is ready 

 for human consumption and the edible product is dredged once again 

 and prepared for shipment. Small wonder, under conditions of such 

 a highly developed system of cultivation, that the oyster is a luxury 

 item. Among recent developments in this industry are dredges based 

 on a vacuum-cleaner principle, which can suck up as much as 3,000 

 bushels in a morning; this mechanism has enormously speeded the 

 transplantation of oysters to different grounds, and obviously it pro- 

 vides for far more efficient control of destructive pests. It is probable 

 that there are still some molluscan sources which are untapped, and 

 there is little doubt that the cultivation of oysters, clams, and other 

 bivalves can be developed on a wider scale. But it is totally unreal- 

 istic to look to these sources for any substantial alleviation of world- 

 wide food shortages ; the best that might be expected would be limited 

 developments in certain areas which might serve directly or indirectly 

 to relieve critical conditions in minimal fashion. 



So we are left with the fact that the great bulk of our harvest of 

 the sea must come from the animals at the end of the food chain — 

 the fishes, which represent the most inefficient level of harvesting. 

 That is to say, they are "inefficient" in terms of total organic produc- 

 tion, although admittedly "efficient" in terms of man's ability to 

 catch fish as compared with his ability to catch plankton. 



Wliat, then, can man do to increase the landings of fisheries on a 

 world-wide scale ? Are these resources inexhaustible ? For example, 

 is the stock of herringlike fishes, which constitutes a major item in the 

 world's fish production, being depleted to the danger point by the 

 ever more intensive and efficient efforts of man ? The world's annual 

 landings at present amount to perhaps 20 million tons. Can we 

 double those landings in a decade by exploiting the present stocks 

 much more fully ? Can we also find new and untapped resources so 

 that the world's production might be increased many times over — say, 

 ten-, fifty- or a hundred-fold? How much will the expanding science 

 of oceanography and the rapid strides in technology help us to increase 

 the production of our fisheries ? 



These questions are difficult to answer with any degree of accuracy. 

 Sober thought and judgment are needed lest the misconception that 

 the ocean offers a panacea for food problems become widespread. 



Reference has been made earlier to the miraculous aids to modern 

 fishing, some of which can be called electronic. About 20 years ago 

 the conventional sounding lead and line gave way to the fathometer, 

 a machine that measured the time required for sound waves sent out 

 from the ship to reach bottom and return an echo to the ship. Given 

 the speed of sound in water, it was possible to construct the instrument 

 so that the depth of water was recorded on a dial, and measurements 

 could be made continuously under full steam. In the early days of 



