RECORD OF THE LARVAE OF THE JACK MACKEREL 

 ( TRACHURUS SYMMgTRICUS ). 1956 



The distribution and relative abundance of jack mackerel larvae in 1956 

 are shown in figure 5. The four categories of abundance are identical to those 

 described for sardine larvae; individual station values represent the cumula- 

 tive standard haul total for the year. The data presented in table V are sum- 

 marized in text table 6, by month and area. The larvae of jack mackerel were 

 described by Ahlstrom and Ball (1954). As in 1955, there were no occurrences 

 off southern Baja California (lines 140-157), and only a few larvae (0.82%) 

 were taken off lower central Baja California (lines 123-137). The area of 

 greatest concentration of larvae differed in the two years: In 1956, the lar- 

 gest concentration (44.3%) occurred off northern Baja California (lines 97-107), 

 while in 1955, most larvae (43.2%) were taken off southern California (lines 

 80-93). 



Jack mackerel larvae are recorded by size classes in table V. 

 have the following midpoints and ranges: 



These 



The standard haul values of jack mackerel larvae for 1956 are compared 

 with those for 1952 through 1955 in text tables 7 and 8. In the former, a 

 summary is given by month; in the latter, by size. The data for the several 

 years are only roughly comparable, since the coverage was somewhat different in 

 each year. 



The seasonal distribution of jack mackerel larvae is unusual in 1956. The 

 greatest abundance of larvae occurred in March, with a secondary peak in June. 

 In the neighboring years, larvae were only moderately abundant in March, and the 

 peak month was either June (1953-55) or July (1952). 



The abundance of larvae by size category is unusual in the paucity of 

 small larvae, particularly 2.0 and 2.5 mm. larvae. It is interesting to note 

 the similarity in abundance of larvae 4.0-5.75 mm. in length during the past 

 three seasons. 



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