opment of the pelagic fisheries for tunas and spearfishes, con- 

 ducted mostly by Japanese fishermen. 



The most recent example is the incipient development of 

 a large new fishery on the western side of the Indian Ocean 

 which, I am sure, will be of major importance. Studies of 

 this area carried out cooperatively during the Indian Ocean 

 Expedition by oceanographers of the United States, England, 

 Russia, and other countries demonstrate that this is a region 

 of high basic productivity, associated with vertical circulation 

 related to the monsoon winds, and there have been observed 

 sizeable populations of sardines, mackerels, tunas, and other 

 fishes. 



Other examples of the utility of oceanography in the location 

 and development of rich new fishing areas are the fisheries 

 developments which are just commencing off the coasts of 

 Chile and Argentina. 



Identification and location of unused resources 



Even in those areas of the sea which have been long ex- 

 ploited by the commercial fisheries, systematic scientific ob- 

 servations may lead to the identification of important latent 

 resources. For example, the systematic studies of the Cali- 

 fornia Current, which have been going on for a number of 

 years, and which had as their initial motivations the investiga- 

 tion of the ecology and fishery dynamics of the California sar- 

 dine, have led to important discoveries of unused resources. 

 One of the techniques of these investigations is systematic sur- 

 veys of the occurrence of sardine larvae and other fish larvae. 

 One dominant element in the catches of fish larvae is the 

 Pacific hake, from which it was inferred that there is a large 

 latent resource of this species which might prove to be com- 

 mercially exploitable. Following this lead, systematic explora- 

 tions by echo sounding and by experimental trawling, have 

 revealed large commercially exploitable concentrations along 

 the coast of Washington, Oregon and northern California. 

 It appears that this species moves south and somewhat offshore 

 to spawn, and moves north on a feeding migration, although 

 many of the details remain to be worked out. Whether the 

 stocks are commercially exploitable, not only off Washington 

 and Oregon, but also to the south in the vicinity of the spawn- 

 ing grounds remains to be investigated. These systematic sur- 

 veys of fish larvae have also revealed that, with the decline 

 of the sardine population, its close competitor, the anchovy, 

 has increased very greatly in abundance. Scientists of the 

 California Cooperative Fishery Investigations estimate that 

 there is off California and Baja California a standing stock of 

 some two to four million tons of anchovies, that could sustain 

 a harvest of perhaps half a million tons per year, or more, and 

 they believe that the reduction of the anchovy population 

 might, at the same time, accelerate the recovery of the sardine 

 population. These investigations have also indicated that the 

 stock of jack mackerel, of which only some 40 to 50 thousand 

 tons per year are currently harvested, extends westward over a 

 vast region of the Pacific and could support a much larger 

 fishery. 



Another example of systematic observations revealing an 

 unrealized resource is the recent development of the expanded 

 fishery for swordfish in the northwest Atlantic, employing 

 floating long-lines at night. This was discovered, almost ac- 

 cidentally, by our colleagues at Woods Hole Oceanographic 

 Institution in the course of their studies related to the bluefin 

 and yellowfin tuna. 



Fish behaviour in relation to catching operations 



The foregoing kinds of information are helpful to the fishing 

 industry in indicating those sea areas, and often also the par- 

 ticular seasons, where abundant exploitable populations occur. 

 The fisherman has, however, additional problems of locating 

 fish shoals within a general area and then of catching them 

 rapidly and efficiently. Knowledge of the local distribution 

 of the fish in relation to the properties of their environment, 

 and knowledge of their behaviour, especially as it may vary in 

 relation to measurable properties of the environment, can be 

 useful to the fisherman in his tactical operations. If the ocean- 

 ographer can indicate to the fisherman what measurements he 

 himself can take at sea in order to guide his scouting and catch- 

 ing operations, this can increase his efficiency and cut down his 

 cost of production. Some success has been achieved in these 

 matters, but I am sure that we can do a good deal better as 

 we learn more. 



One of the things that both scientists and fishermen have 

 known how easily to measure for a great many years is water 

 temperature, both surface and subsurface. Also, the surface 

 temperature of the ocean is the one physical measurement that 

 is, and has been for many years, routinely observed as part of 

 the merchant ship weather reporting system. Consequently, 

 we have been able to learn a good deal about the local distribu- 

 tions of some kinds of fish in relation to temperature, and this 

 knowledge can be of some tactical advantage to the fishermen. 

 A few examples: 



The North Pacific albacore, which are summer visitors to 

 waters off the west coast of the United States, prefer water of 

 temperature 60 to 66 °F, about two-thirds of the total catch 

 being made in waters of these temperatures. In directing their 

 scouting operations, therefore, it is useful to the fishermen to con- 

 sult the sea-surface temperature charts which are published by 

 the Bureau of Commercial Fisheries at two-week intervals 

 during the summer, and to take their own temperature measure- 

 ments while searching for the albacore schools. 



At the northern and southern extremes of their ranges, the 

 distributions of the tropical tunas, yellowfin and skipjack, vary 

 in relation to the water temperature, being limited by the lowest 

 temperatures in which these species occur in commercial con- 

 centrations. Within the range of tolerable temperatures, how- 

 ever, the location of fish concentrations appears to be related to 

 the food supply. All along Baja California there are large 

 crops of forage organisms at all times of the year, yet the yellow- 

 fin tuna are found in there in commercial quantities only in 

 waters of about 19°C and warmer, while skipjack occur in 

 somewhat cooler water, down to about 17°C. These tempera- 

 tures also limit the distributions of these species at the southern 



1! 



