Some results obtained by the staff of the 

 Bureau of Commercial Fisheries Biological 

 Laboratory, Honolulu, Hawaii, show catches of 

 zooplankton in net hauls made within 5 to 10 

 miles of a front in the central equatorial 

 Pacific. The highest catches were in the front 

 and on the warmer side, about 5 miles away. 

 The volumes caught 5 miles away on the cooler 

 side and 10 miles away on the warmer side, 

 were roughly equal, though significantly less 

 than the above-mentioned highest volumes. 

 Again, these data do not indicate the cause of 

 the plankton distribution. 



Knauss (1957), describing a front in the 

 tropical Pacific (ca. 3° N., 120° W.), probably 

 between South Equatorial Current water and 

 Equatorial Counter-current water, says, "High 

 biological activity was associated with the 

 front; however, there was no floating debris. 

 The cold water was relatively sterile; most of 

 the life appeared to be concentrated in the 

 relatively narrow frontal zone". The biological 

 observations were made by persons using a 

 dipnet only. 



An oceanic front is named by analogy with 

 an atmospheric front (p. 2). Doubtless the 

 analogy does not end there, yet their similari- 

 ties are general or remain largely unknown. 

 Even so, one may speculate on whether atmos- 

 pheric biota are affected by an atmospheric 

 front in a way similar to the way oceanic biota 

 are affected by an oceanic front. In this regard, 

 a study by Sayer (1962) of the movements, over 

 many days, of locust swarms in a major 

 atmospheric front in Somaliland is most in- 

 teresting. The locusts showed continued aggre- 

 gation at the front. They were swept upward in 

 the acute angle between the inclined interface 

 of the front and the ground, and then glided 

 downward only to be returned to the interface 

 by the wind. In this spiralling fashion they 

 moved slowly along the frontal axis. 



In contrast to the relatively ill- substantiated 

 idea that frontal systems are focuses of high 

 standing-crops of zooplankton is the much 

 better substantiated idea that some frontal 

 systems are sites of relatively high abundance 

 of pelagic fishes (Uda, 1953, 1954, 1959, 1961). 

 Japanese fisheries for bluefin, albacore, and 

 skipjack are closely related to the frontal 

 system formed by the Oyashio and Kuroshio 

 (Uda and Ishino, 1958); so is the whale fishery 

 (Uda, 1938, 1954). 



The frontal system between the Gulf Stream 

 and the Labrador Current is not the focus of 

 intense fishing such as there is off Japan. 

 Nevertheless, yellowfin and bluefin tuna are 

 strongly associated with the Gulf Stream front. 

 Anonymous, 1959; Hela and Laevastu, 1962; 

 Rivas, 1955; Laevastu and Rosa, 1963; Squire, 

 1963; Walford, 1958). 



There is a major front in the NorwegianSea 

 where mature herring aggregate for feeding in 

 summer, between spawning, (Devoid, 1963). 

 Eggvin (1940) describes the advance of a cold 



front of Baltic water through the Skagerrak 

 northwards along the Norwegian coast in the 

 early spring. This front, however, does not 

 attract the herring but drives them off shore and 

 out of their favored habitats in ways that vary 

 from year to year, according to Eggvin. 



Robins (1952) demonstrated a marked in- 

 crease in troll catches of skipjack in a rela- 

 tively weak front in the entrance to Storm Bay, 

 Tasmania. 



Relatively little detailed work has beendone 

 on oceanic frontal systems in spite of ocean- 

 ographers' manifest interest in them. What 

 has been done has been overwhelmingly phys- 

 ical and dynamical, and generally on a large 

 scale (e.g.. Gulf Stream studies). The litera- 

 ture has few quantitative biological measure- 

 nnents at fronts, especially the smaller, 

 sharper ones, because such investigations are 

 difficult to carry out. 



The fronts studied by the S TOR program have 

 two points of general interest: ( 1 ) judging from 

 the literature, they have been more compre- 

 hensively studied than any others (though not 

 necessarily in any particular aspect); and (2) 

 they occur in an area across which yellowfin 

 and perhaps skipjack normally migrate, at a 

 time of year when these fronts are best 

 developed. These studies contribute to our 

 knowledge of a relatively little-known phenom- 

 enon- -the so-called Cape San Lucas front. 

 This frontal system may influence the seasonal 

 movement of tuna into the "local banks " fishery 

 off the west coast of Lower California, though 

 we do not know this. 



A short review of the results presented in 

 this paper was prepared, with a somewhat dif- 

 ferent emphasis, for the World Scientific Meet- 

 ing on the Biology of Tunas and Related Species, 

 held at La Jolla, Calif., in July 1962 (Griffiths, 

 1963). 



OBSERVATIONS 



Table 1 summarizes the main observations 

 made; figure 1 shows the approximate loca- 

 tion of the observations as well as the station 

 patterns of STOR cruise TO-60-1 and part of 

 CalCOFl cruise 6004-B. Complementary 

 notes, some clarifying special difficulties, 

 follow. Further information is given, where 

 necessary, in the section "Results and Discus- 

 sion." The original data will appear ina report 

 on the above-mentioned cruises, and will in- 

 clude data on front 5 (TO- 61-1). 



Track 



When observations were made close enough 

 to land, bearings were taken on landmarks 

 (mountains, points, lighthouses, etc.), but these 

 bearings were accurate to no better than the 

 nearest half-degree, which introduces small, 

 unknown errors into the plotting of the ship's 



