CalCOFI Reports, Vol. 11, 1967 - California Cooperative Oceanic ...

102 CALIFORNIA COOPERATIVE OCEANIC FISHERIES INVESTIGATIONSrecruit group originates through intensive and concentratedspawning and subsequent favorable conditionsfor survival. Ahlstrom (1959, p. 203) thoughtfirst that a widespread spawning of the Californiasardine favored greater survival and bigger recruitment,but a closer analysis of later data led him todoubt this conclusion.It was stated that a strong recruit group couldoriginate from an intense but geographically restrictedspawning. This, however, did not occur as aresult of the intensive spawning observed in areasB and C during 1962-63. The resulting group waspoor according to the abundance estimates shown inFigure 6. On the other hand the low egg numbers in1963-64 gave rise to an estimated rich recruit group.Evidently more effort is needed to tie up biologicalfacts and oceanographic evidence.The best conformity between egg numbers andrecruitment strength was found in areas D and E asshown in Figure 7. Here the trend follows the samepattern both as regards eggs and recruits.FREQUENCY OF LARVAEIt must be borne in mind that the Hensen netis very selective as to larval sizes caught. Only theEGGS: AREAS D y Eyoungest stages (less than 10 mm in length) areeffectively retained by the net. We still lack experimentalevidence as to incubation time and the rateof larval growth, but presumably the incubation timeis shorter than the growth time of larval stageseffectively retained. Until this time factor has beenptudied the numbers of eggs and larvae are notdirectly comparable, but if larval growth representsa longer time the numbers of larvae are maximalnumbers in comparison, and we can conclude thatTABLE 3PERCENTAGES OF ANCHOVY LARVAE VERSUS EGGS IN THEHENSEN NET HAULSWinter--- ...............spring_^.........^_^^^^^Summer-- ._-.- - - - - - --.-.Autumn .................Average percent- - - - -Percent of larvaeper positiveStation2810223720Percent of larvaeperStation3213293325.I*.POSITIVE STATlOk[r 75-Wa-0W0 70.LLLL0KWm z3-5 -~~ ~RECRUITS(Total Group)* o I IIE M M J S N E M M J S N E M M J S N E M M J S N E M M J1961 1962 1963 1964 1965FIGURE 7.